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Variation of polyphenols in a germplasm collection of globe artichoke
Food Research International 46 (2012) 544–551
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Variation of polyphenols in a germplasm collection of globe artichoke Sara Lombardo a, Gaetano Pandino a, Anita Ierna b, Giovanni Mauromicale a,⁎ a b
Dipartimento di Scienze delle Produzioni Agrarie ed Alimentari, Università degli Studi di Catania, via Valdisavoia 5, 95123 Catania, Italy Istituto per i Sistemi Agricoli e Forestali del Mediterraneo, CNR, Sezione di Catania, Str.le V. Lancia, Zona Industriale; Blocco Palma I 95121 Catania, Italy
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Article history: Received 26 January 2011 Accepted 16 June 2011 Keywords: Cynara cardunculus var. scolymus Polyphenols Antioxidant activity Germplasm Plant part Harvest time
a b s t r a c t Globe artichoke, a crop native to the Mediterranean Basin, is rich in polyphenols whose health-promoting properties have been well documented in literature. Here, we reported the variation of polyphenol content and antioxidant activity in plant parts (floral stem, receptacle, inner and outer bracts) of 17 cultivars. Our objectives were also to evaluate the influence of harvest time (winter and spring) on total polyphenol content and to assess the polyphenol composition by HPLC in six cultivars not previously analysed. The total content and profile of polyphenols were significantly different amongst cultivars and plant parts. ‘Tema 2000’, ‘Nobre’ and ‘Violetto di Sicilia clone 4/8’ had the highest level of total polyphenol content, whilst ‘Camerys’ and ‘Tempo’ had the lowest. Polyphenols resulted more abundant in the floral stem and receptacle. These were, respectively, rich in caffeoylquinic acids and apigenin derivatives. Each cultivar preferentially accumulated polyphenols in specific plant parts and, hence, may have a specific end-use based on its polyphenol content. In this view, the high level of total polyphenols in the receptacles of ‘Tema 2000’, ‘Opal’ and ‘Nobre’ makes them more suitable for the fresh consumption, whereas the floral stems of ‘Violetto di Sicilia clone 4/8’, ‘Nobre’ and ‘Tema 2000’ are suggested for the exploitation as source of natural antioxidants. In addition, the cultivar-dependency of both polyphenol content and antioxidant activity of globe artichoke extracts led to foresee the possible manipulation by specific breeding and selection programmes in order to improve the health-beneficial properties of globe artichoke head. Our findings prove also the influence of harvest time on the polyphenol content and thus suggest giving specific consideration to the other factors (e.g. temperature and photoperiod) that may affect polyphenol biosynthesis and accumulation in globe artichoke plant. © 2011 Elsevier Ltd. All rights reserved.
1. Introduction Polyphenols are a well studied group of secondary metabolites widely distributed throughout the plant kingdom (Kähkönen et al., 1999). Structurally, they range from simple molecules to highly polymerised compounds (Manach, Scalbert, Morand, Rémésy, & Jimènez, 2004). They are involved in numerous physiological and biochemical processes of the plant, including defence against pathogens and parasites, wound repair and protection from atmospheric pollution and extreme temperatures (Beckman, 2000; Bravo, 1998). Some polyphenols have been also associated with the sensory, nutritional and medicinal properties of particular foodstuffs (Scalbert & Williamson, 2000; Shahidi & Naczk, 1995; Zdunczyk et al., 2002). In recent years, the globe artichoke [Cynara cardunculus L. var. scolymus (L.) Fiori= C. scolymus L.] has got a renewed interest as source of bioactive compounds (Lattanzio, Kroon, Linsalata, & Cardinali, 2009). It is a herbaceous crop native to the Mediterranean Basin, where its
Abbreviations: CAE, chlorogenic acid equivalent; DM, dry matter; DPPH, 2,2-diphenyl1-picrylhydrazyl; FM, fresh matter; L/D, length/diameter ratio of head; TPC, total polyphenol content. ⁎ Corresponding author. Tel.: + 39 095 234 409; fax: + 39 095 234 449. E-mail address: [email protected] (G. Mauromicale). 0963-9969/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2011.06.047
commercial production gives a significant contribution to the agricultural economy. Today, globe artichoke heads production is widely diffused all over the world (133 kha), even if it is concentrated in Southern Europe with Italy as the leading producer (about 487 kt per year), followed by Spain and France (about 199 and 45 kt per year, respectively). Globe artichoke is also cultivated in the Near East, North Africa, South America, United States (California) and recently its cultivation is spreading in China (10 kha) and Peru (8 kha) (FAO, 2009). The edible part of the plant is the enlarged receptacle and the tender thickened bract bases of the head (capitulum), which is the immature Asteraceae (Compositae) inflorescence, used worldwide as both a fresh and canned delicacy. Furthermore, globe artichoke has a healthy image also related to the polyphenols present in the leaves and inflorescences, with phenolic acids (mono- and di-caffeoylquinic acids) and flavonoids (luteolin and apigenin derivatives) as the major bioactive substances (Lattanzio et al., 2009; Lombardo et al., 2010; Pandino, Lombardo, Mauromicale, & Williamson, 2011a,b; Schütz, Kammerer, Carle, & Schieber, 2004). In literature, previous works extensively studied the qualitative and quantitative polyphenol profiles of the globe artichoke, but most of them examined unknown cultivars obtained from local markets rather than from experimental fields (Brat et al., 2006; Racchi et al., 2002) or were limited to few cultivars (Alamanni & Cossu, 2003; Curadi,
S. Lombardo et al. / Food Research International 46 (2012) 544–551
Ceccarelli, Graifenberg, & Picciarelli, 2004). In recent years we have investigated the polyphenol profile of several globe artichoke cultivars maintained in the germplasm collection at Catania University (Lombardo et al., 2010; Pandino, Courts, Lombardo, Mauromicale, & Williamson, 2010; Pandino et al., 2011a,b). Screening of further globe artichoke cultivars relative to polyphenol content is of particular interest for the biodiversity preservation. In fact, this important nutritional and technological characteristic could be a natural tool to bestow a specific end-use on cultivars. At present, the germplasm of globe artichoke is characterised by a great number of commercial and local cultivars, different for biological, morphological and qualitative traits. Our intention was to promote cultivars with high polyphenol content of the receptacle (edible fraction) for fresh consumption and to consider those with higher polyphenol amounts in the waste (floral stem and bracts) for the recovery of these bio-compounds. On the other side, cultivars characterised by lower levels of polyphenols would be predestined for minimally processed foods. In this light, the aim of the present study was to evaluate the total polyphenol content and antioxidant activity of seventeen globe artichoke cultivars (both widely cultivated, landraces and novel ‘seed’ propagated cultivars) in relation to plant part (floral stem, receptacle, inner and outer bracts) and harvest time (winter and spring). Here, for the first time, we characterised the polyphenol profile of six cultivars, aimed to provide further information about the available globe artichoke germplasm and to better exploit this as potential natural source of these phytochemicals.
2. Material and methods 2.1. Site, soil and climate of field experiments Field experiments were conducted during 2006–2007 at the experimental station of Catania University on Catania Plain (37°25′N, 15°30′E, 10 m a.s.l.), in a typic and/or vertic xerochrepts soil (USDA, Soil Taxonomy). The Catania Plain is a typical area for globe artichoke cultivation in the Mediterranean Basin. The soil characteristics were: clay 45%, silt 28%, sand 27%, organic matter 1%, total nitrogen 0.1%, available P2O5 10 ppm, exchangeable K2O 210 ppm, and pH 7.2. The local climate is semi-arid-Mediterranean, characterised by mild rainy winters and hot, rainless summers. The mean 30-year maximum monthly temperature ranges between 14.8 °C (January) and 30.6 °C (July), and the minimum temperature between 7.8 °C (January) and 22.3 °C (August).
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2.2. Plant material, experimental design and management practices Seventeen globe artichoke cultivars (Table 1) were manually planted in the form of either semi-dormant offshoots (“ovoli”) or seeds (achenes) in August 2006. The plant material was arranged in a randomised block experimental design with four replications, adopting a planting density of 1.0 plant m− 2 (equivalent to a within row plantto-plant spacing of 0.80 m apart, and a row-to-row spacing of 1.25 m). Each experimental unit consisted of 10 plants. A typical fertiliser programme (200 kg N, 80 kg P2O5 and 100 kg K2O per ha) was applied. Drip irrigation was carried out during the summer, when the accumulated daily evaporation reached 35 mm (equivalent to 100% of maximum evapotranspiration). Pest control followed standard commercial practice. No gibberellic acid was applied to the plants during the crop cycle. 2.3. Morphological description of the cultivars At least 5 heads per replicate were harvested, with the floral stem including 2–3 leaves, at the usual marketing stage and regardless of size. At this stage, the length of the central floral buds was about 2 mm (Mauromicale & Ierna, 2000). After harvesting, the floral stem was removed from the head by cutting 0.5 cm under the receptacle. All heads were weighed and their maximum diameter and length measured. Head length/diameter ratio (L/D ratio), an important index of its shape, was calculated. L/D ratio is a relatively constant trait of each cultivar, varying from 0.9 to 1.1 and ≥1.2 in spherical/sub-spherical and in long shaped types, respectively (Mauromicale & Ierna, 2000). The colour of the outer and inner bracts was recorded on the basis of visual evaluation. 2.4. Sample preparation The heads harvested were mixed, washed with tap water and separated into outer bracts (~ 15 external bracts), inner bracts (remaining bracts) and receptacle. The floral stem, previously separated from its head, was also cleaned and dried. Each part of the inflorescence, including the floral stem, was sliced into small pieces (b0.5 cm), immediately blended using a domestic food processor at 0 °C (Kenwood multipro, Milan, Italy). Finally, an amount of each fraction was freezedried using a Christ freeze drier (Osterode am Harz, Germany), divided into three replicates and stored at −20 °C until HPLC analysis, whereas the remaining portion was directly used to analyse the total polyphenol
Table 1 Main head characteristics of globe artichoke cultivars under study. Different letters within each column indicate statistically significant differences between means (P ≤ 0.05). Cultivar
Fresh weight (g)
L/D
1. Blanc Hyérois 2. Camard 3. Camerys 4. Concerto 5. Empolese 6. Harmony F1 7. Locale di Mola 8. Madrigal F1 9. Nobre 10. Opal 11. Romanesco clone C3 12. Spinoso di Palermo 13. Tema 2000 14. Tempo 15. Tondo di Paestum 16. Violetto di Provenza 17. Violetto di Sicilia clone 4/8 Mean CV (%)
197 186 173 201 216 225 163 219 147 195 144 153 167 176 210 125 117 177 19
1.20 0.89 0.98 1.25 1.20 1.15 1.42 1.15 1.03 1.20 1.05 1.48 1.25 1.30 1.00 1.45 1.50 1.21 15
ac bf dg ad ab a eg a gi ac gi fh eg cg ac hi i
de h g cd de e b e fg de f ab cd c fg ab a
Colour of outer bracts
Colour of inner bracts
Green Green with purple shades Green with purple shades Deep purple Purple with green shades Green Purple with green shades Green Green Purple with green shades Purple with green shades Green with purple shades or purple with green shades Deep purple Purple with green shades Purple with light green shades Purple with green shades Green with purple shades – –
Yellow-greenish Yellow-greenish with purple shades Yellow-purple Yellowish-green Yellow with purple shades Yellow Yellow with purple shades Yellow Yellow Yellowish-green Yellow-greenish with purple shades Yellowish-green with purple shades Yellow with purple shades Yellow-purple Yellow-purple Yellow-purple Yellow-greenish – –
Cultivar 12 is spiny, cultivars 6, 10 and 13 are mucronate and the remaining are spineless; L/D: length/diameter ratio of head; and CV: coefficient of variation.
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content and antioxidant activity. The heads of two cultivars (‘Romanesco clone C3’ and ‘Tema 2000’) were collected in winter and spring, aimed at studying the influence of harvest time on the total polyphenol content. 2.5. Chemicals Reagents and solvents of analytical grade, used for total polyphenol content and antioxidant activity assays, were purchased from Sigma Aldrich (Milan, Italy), whilst those for HPLC analysis were obtained from VWR (Milan, Italy) and were of analytical or HPLC grade. Apigenin-7-Oglucoside, apigenin-7-O-rutinoside, apigenin, luteolin-7-O-glucoside, luteolin, 5-O-caffeoylquinic acid (chlorogenic acid) and hesperetin were obtained from Extrasynthese (Lyon, France), cynarin (1,3-di-O-caffeoylquinic acid) was from Applichem GmbH (Darmstadt, Germany), and butylated hydroxytoluene (BHT) was purchased from Sigma Aldrich (Milan, Italy). Deionised water was used throughout. 2.6. Analysis of total polyphenol content For the extraction of total polyphenols, 5 g per replicate was treated with 50 mL of methanol containing 1% hydrochloric acid, blended for 2 min in an Ultra-Turrax T18 (Janke & Kunkel Ika-Labortechnik, Staufen, Germany) and stirred at room temperature for 1 h. The filtrate (through Whatman No. 4 filter paper) was stored at −20 °C until required. The Folin–Ciocalteu assay (Singleton & Rossi, 1965) was used to quantify the total polyphenol content (TPC). The absorbance was measured at 760 nm using a Shimadzu 1601 UV–Visible spectrophotometer (Tokyo, Japan). The total polyphenol content was determined on the basis of a standard calibration curve generated with known amounts of chlorogenic acid and expressed as grammes of chlorogenic acid equivalent (CAE) per kilogramme on both fresh matter (FM) and dry matter (DM) bases. Data are mean of three independent experiments (n = 3).
(IUPAC, 1976). Luteolin-7-O-glucuronide, luteolin-7-O-rutinoside and luteolin malonylglucoside were quantified at 350 nm using luteolin-7O-glucoside as a reference. Finally, apigenin-7-O-glucuronide and apigenin malonylglucoside were estimated at 310 nm, using apigenin7-O-glucoside as a reference. All peak areas and retention times were expressed relative to the internal standard of hesperetin added prior to extraction of samples. All data are presented as mean± standard deviation of three individual experiments (n = 3), and expressed as mg/kg of dry matter (DM). 2.8. Determination of antioxidant activity The antioxidant activity of the extracts was evaluated as percentage inhibition of DPPH radical (Brand-Williams, Cuvelier, & Berset, 1995). An aliquot (0.1 mL) of each extract, used for total polyphenol assay, was added to 3.9 mL of freshly prepared methanolic solution containing 0.24 g L − 1 DPPH, and held in the dark for 30 min at room temperature. Then, the absorbance was measured at 515 nm in 1 cm cuvettes, using a Shimadzu 1601 UV–Visible spectrophotometer (Tokyo, Japan). The working solution was prepared by dilution of methanolic DPPH to absorbance at ≃1.1 AU to gain the sufficient reaction capacity for higher contents of antioxidant in extracts. The percentage inhibition of DPPH was obtained by the following equation: [(AC(0) − AS(t))/AC(0)] × 100, where AC(0) is the absorbance of the blank control at the beginning of the assay, and AS(t) the sample absorbance after 30 min. 2.9. Statistical analysis All data were subjected to Bartlett's test for homogeneity of variance, before being subjected to analysis of variance. Means were separated by the Tukey's HSD or Student–Newmann–Keuls tests, when the F-test was significant. 3. Results
2.7. Quali-quantitative characterisation of phenolics by HPLC analysis
3.1. Head characteristics of the cultivars
2.7.1. Extraction procedure The extraction procedure, performed for six cultivars (i.e. ‘Camard’, ‘Camerys’, ‘Empolese’, ‘Locale di Mola’, ‘Opal’ and ‘Spinoso di Palermo’), was carried out as previously described by Pandino et al. (2010).
The main characteristics of head showed a high variability amongst cultivars with respect to size, shape (length/diameter, L/D, ratio) and colour of inner and outer bracts (Table 1). The average fresh weight of head varied from 117 g (‘Violetto di Sicilia clone 4/8’) to 225 g (‘Harmony F1’). Head shape was sub-spherical (L/D ratio 0.89) in ‘Camard’, spherical (about 1.02) in ‘Camerys’, ‘Nobre’, ‘Romanesco clone C3’ and ‘Tondo di Paestum’, cylindrical (1.42–1.50) in ‘Violetto di Sicilia clone 4/8’, ‘Violetto di Provenza’ and ‘Locale di Mola’, and conical (1.48) in ‘Spinoso di Palermo’. The colour of the outer bracts varied from deep green (e.g. ‘Blanc Hyérois’,) to deep purple (‘Tema 2000’ and ‘Concerto’) with a wide range of different colour hues. The colour of the inner bracts was yellow (e.g. ‘Nobre’), yellow with greenish (‘Blanc Hyérois’ and ‘Violetto di Sicilia clone 4/8’) or purple shades (e.g. ‘Tema 2000’).
2.7.2. HPLC analysis Each extract (20 μL) was analysed using a series 1200 HPLC instrument (Agilent Technologies, Palo Alto, CA) equipped with ChemStation software (B.03.01). Separations were achieved on a Zorbax Eclipse XDB-C18 (4.6× 150 mm; 5.0 μm particle size), operated at 30 °C, with a 0.2 μm stainless steel in-line filter. The method was adapted from Pandino et al. (2010): the mobile phase was 1% formic acid in water (solvent A) and in acetonitrile (solvent B) at a flow rate of 0.5 mL/min. The gradient started with 5% B to reach 10% B at 10 min, 40% B at 30 min, 90% B at 50 min, and 90% B at 58 min. Chromatograms were recorded at 280, 310, and 350 nm from diode array data collected between 200 and 600 nm. 2.7.3. Polyphenols' identification and quantification In this paper, 17 compounds, belonging to caffeoylquinic acids and flavones' groups, were separated using HPLC and identified by their retention times, comparison with commercially available standards, their UV/Vis spectra and available data in the literature (Lombardo et al., 2010; Pandino et al., 2011a,b). The LOD (limit of detection) and LOQ (limit of quantification) were reported in a previous study (Pandino et al., 2010). Amounts of mono- and di-caffeoylquinic acids were calculated at 310 nm using 5-caffeoylquinic acid and cynarin as references, respectively. In this paper, the caffeoylquinic acids are presented according to the recommended IUPAC numbering system
3.2. Total polyphenol content The total polyphenol content of the whole head, expressed either on a FM or a DM basis, was significantly cultivar-dependent (Table 2). ‘Tema 2000’ had the highest total polyphenol content of the whole head (7.4 g CAE kg− 1 FM, 58.7 g CAE kg− 1 DM), but ‘Nobre’ (6.7 g CAE kg− 1 FM, 40.1 g CAE kg− 1 DM) and ‘Violetto di Sicilia clone 4/8’ (6.4 g CAE kg− 1 FM, 47.0 g CAE kg− 1 DM) also represented a rich source of these compounds (Table 2). The lowest values were found in ‘Tempo’ (1.6 g CAE kg − 1 FM, 11.9 g CAE kg − 1 DM) and ‘Camerys’ (1.7 g CAE kg− 1 FM, 13.9 g CAE kg− 1 DM). The deviation was 393% on a FM basis and 403% on a DM basis. A significant (P ≤ 0.05) “cultivar× plant part” interaction (Table 3) was found. For example, ‘Tema 2000’ showed the highest total polyphenol content in the outer bracts and receptacle, whereas ‘Nobre’ and ‘Violetto di Sicilia clone 4/8’ obtained the highest
S. Lombardo et al. / Food Research International 46 (2012) 544–551 Table 2 Total polyphenol content (TPC) and dry matter (DM) contents of the whole globe artichoke head in relation to cultivar. Different letters within each column indicate statistically significant differences between means (P ≤ 0.05). Cultivar
TPC (g CAE kg− 1 FM)a TPC (g CAE kg− 1 DM) DM (%)
Blanc Hyérois Camard Camerys Concerto Empolese Harmony F1 Locale di Mola Madrigal F1 Nobre Opal Romanesco clone C3 Spinoso di Palermo Tema 2000 Tempo Tondo di Paestum Violetto di Provenza Violetto di Sicilia clone 4/8 Mean CV (%)
5.0 4.5 1.7 3.7 5.6 4.7 5.2 3.7 6.7 4.5 4.7 3.8 7.4 1.6 4.4 5.6 6.4 4.6 33
de (7) f (11) h (15) g (14) c (5) ef (8) cd (6) g (14) b (2) f (10) ef (9) g (13) a (1) h (16) f (12) c (4) b (3)
40.3 26.6 13.9 28.0 41.2 34.6 48.6 31.4 40.1 34.4 40.9 32.5 58.7 11.9 30.8 41.5 47.0 35.4 33
c (7) f (15) g (16) ef (14) c (5) d (9) b (2) de (12) c (8) d (10) c (6) e (11) a (1) h (17) de (13) c (4) b (3)
12.4 eg 16.9 a 12.2 eg 13.2 ce 13.6 bc 13.6 bc 10.7 h 11.8 fg 16.7 a 13.1 ce 11.5 gh 11.7 fh 12.6 df 13.4 bd 14.3 b 13.5 bd 13.6 bc 13.2 12
CAE: chlorogenic acid equivalent; FM: fresh matter; DM: dry matter; values in brackets represent the ranking order; and CV: coefficient of variation. a The data reported on a FM basis are calculated considering the incidence of each head parts (i.e. receptacle, inner and outer bracts) on the whole head weight.
values for the inner bracts and floral stem, respectively. ‘Camerys’ and ‘Tempo’ showed low levels of total polyphenol content in all plant parts (Table 3). Regardless of the cultivar (Table 3), the floral stem exhibited the highest total polyphenol content, whereas the outer bracts had the lowest amounts. The receptacle was fairly rich in total polyphenols (6.6 g CAE kg− 1 FM), whilst the inner bracts had an intermediate content (5.2 g CAE kg− 1 FM) (Table 3). Finally, the total polyphenol content of the whole head was significantly affected by harvest time, resulting higher in spring than in winter (6.0 vs. 5.2 g CAE kg− 1 FM). In particular, passing from winter to spring harvest the level of total polyphenols increased by 17 and 12%, respectively, in ‘Tema 2000’ and ‘Romanesco clone C3’ (data not shown).
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3.3. Quali-quantitative characterisation of polyphenol profile Concerning the quantitative and qualitative profiles of the individual polyphenols (flavones and caffeoylquinic acids), significant differences amongst cultivars and plant parts were found (Tables 4–7). From a quantitative point of view, total apigenin derivatives were the major polyphenol compounds in the receptacle, inner and outer bracts (2504 mg kg − 1 DM, on average of cultivars and plant parts), whereas in the floral stem caffeoylquinic acids were the most abundant (3436 mg kg − 1 DM, on average of cultivars) (Tables 4–7). Amongst the caffeoylquinic acids, 5-O-caffeoylquinic acid and 1,5-diO-caffeoylquinic acid were the main compounds and present mainly in the receptacle and floral stem. The remaining caffeoylquinic acids (i.e. 1- and 3-O-caffeoylquinic acids, 3,4-, 3,5- and 4,5-di-O-caffeoylquinic acids) were minor compounds in all parts of the plant analysed in this study (Tables 4–7). In particular, 3-O-caffeoylquinic acid, 3,4- and 3,5-di-O-caffeoylquinic acids were only present in ‘Locale di Mola’ and ‘Opal’ floral stems (Table 7). Apart from ‘Locale di Mola’ outer bracts, apigenin 7-O-glucuronide was the predominant flavones in the receptacle, inner and outer bracts, ranging from 177 (floral stem of ‘Empolese’) to 3901 mg kg− 1 DM (inner of ‘Camerys’) (Tables 4–7). ‘Camerys’ revealed the highest content of this compound in all plant parts analysed, but high amounts were also found in the receptacles of ‘Opal’ and ‘Empolese’ (2424 mg kg − 1 DM, on average; Table 6) and in the inner bracts of ‘Spinoso di Palermo’ and ‘Locale di Mola’ (2144 mg kg − 1 DM, on average; Table 5). In addition, ‘Opal’ receptacle, together with that of ‘Camard’, was also the richest in apigenin 7-O-glucoside and apigenin aglycone (591 and 160 mg kg− 1 DM, respectively; Table 6). Apigenin malonylglucoside was detected in all head parts and only in trace amounts in the floral stem (Tables 4–7). Except for ‘Locale di Mola’, total luteolin derivatives were abundant in the receptacle (375 mg kg− 1 DM, on average of cultivars) (Tables 4–7). In particular, the receptacles of ‘Camerys’ (567 mg kg− 1 DM) and ‘Spinoso di Palermo’ (506 mg kg− 1 DM) are worth being mentioned for their high contents of luteolin 7-O-glucoside and -glucuronide, respectively. As shown in Tables 4–7, luteolin and luteolin 7-O-rutinoside were minor compounds in all plant parts studied, whilst luteolin malonylglucoside was detected only in the floral stem (47 mg kg− 1 DM, on average of cultivars) (Table 7).
Table 3 Total polyphenol (TPC) and dry matter (DM) contents of plant parts in relation to cultivar. Different letters within each column indicate statistically significant differences between means (P ≤ 0.05). Cultivar
Blanc Hyérois Camard Camerys Concerto Empolese Harmony F1 Locale di Mola Madrigal F1 Nobre Opal Romanesco clone C3 Spinoso di Palermo Tema 2000 Tempo Tondo di Paestum Violetto di Provenza Violetto di Sicilia clone 4/8 Mean CV (%)
Outer bracts
Inner bracts
Receptacle
Floral stem
TPC (g CAE kg− 1 FM)
DM (%)
TPC (g CAE kg− 1 FM)
DM (%)
TPC (g CAE kg− 1 FM)
DM (%)
TPC (g CAE kg− 1 FM)
DM (%)
2.7 fi (12) 3.4 cf (7) 2.0 ij (15) 2.3 gi (13) 3.1 df (8) 2.7 fi (12) 3.7 cd (5) 3.6 ce (6) 4.0 bc (4) 2.8 fh (11) 2.9 eg (9) 2.1 hi (14) 5.3 a (1) 1.4 j (16) 2.9 fh (10) 4.0 bc (3) 4.6 b (2) 3.1 30
12.7 18.6 12.8 14.8 14.0 15.1 12.4 14.1 18.6 14.5 13.9 10.8 15.8 15.6 15.1 15.2 13.7 14.6 14
6.3 cd (7) 4.6 ef (10) 1.6 g (15) 3.8 f (13) 6.8 bc (5) 5.1 de (8) 6.4 c (6) 3.4 f (14) 8.1 a (1) 4.0 ef (12) 5.1 de (9) 4.4 ef (11) 7.8 ab (3) 1.3 g (16) 5.1 de (8) 7.4 ac (4) 7.9 ab (2) 5.2 38
12.8 ad 14.9 a 11.4 bd 11.6 ad 11.6 ad 12.5 ad 9.4 d 11.2 bd 14.2 ab 12.4 ad 10.4 cd 11.5 ad 10.6 cd 11.6 ad 12.9 ac 13. 0 ac 11.2 bd 12.0 11
7.2 ce (7) 5.0 hi (14) 3.9 j (16) 6.2 eg (11) 7.9 bc (5) 7.6 bd (6) 6.5 df (9) 4.6 ij (15) 8.5 b (3) 8.6 b (2) 8.0 bc (4) 5.7 fh (12) 11.3 a (1) 2.4 k (17) 6.3 eg (10) 5.4 gi (13) 7.1 de (8) 6.6 31
11.4 cd 15.2 a 11.9 bd 13.0 ad 14.8 ab 12.4 ad 12.7 ad 11.3 cd 13. 8 ad 11.4 cd 11.0 d 12.6 ad 12. 6 ad 11.4 cd 14.7 ab 13.6 ad 14.2 ac 12.8 10
5.1 f (11) 3.8 gh (13) 1.2 i (17) 2.8 h (15) 9.8 d (5) 7.8 d (7) 10.3 c (4) 8.1 d (6) 16.3 b (2) 7.3 de (8) 6.6 e (9) 3.6 gh (14) 16.0 b (3) 1.4 i (16) 4.2 fg (12) 5.1 f (10) 17.6 a (1) 7.5 66
11.0 ac 10.9 ac 8.6 c 10.6 ac 11.4 ac 10.2 bc 11.0 ac 11.5 ac 14.2 a 11.0 ac 8.4 c 9.5 c 10.6 ac 9.8 c 8.8 c 11.6 ac 13.4 ab 10.7 14
df a df bc be bc ef be a bd be f b bc bc bc ce
CAE: chlorogenic acid equivalent; FM: fresh matter; Values in brackets represent the ranking order; and CV: coefficient of variation.
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Table 4 Polyphenol (mg kg− 1 DM) content of outer bracts in relation to cultivar. Different letters amongst cultivars for each compound indicate statistically significant differences between means (P ≤ 0.05). Compound
1-O-caffeoylquinic acid 3-O-caffeoylquinic acid 5-O-caffeoylquinic acid 3,4-di-O-caffeoylquinic acid 3,5-di-O-caffeoylquinic acid 1,5-di-O-caffeoylquinic 4,5-di-O-caffeoylquinic Total caffeoylquinic acid Luteolin 7-O-rutinoside Luteolin 7-O-glucoside Luteolin 7-O-glucuronide Luteolin malonylglucoside Luteolin Total luteolin Apigenin 7-O-rutinoside Apigenin 7-O-glucoside Apigenin 7-O-glucuronide Apigenin malonylglucoside Apigenin Total apigenin
Cultivar Camard
Camerys
Empolese
Locale di Mola
Opal
Spinoso di Palermo
nd nd nd nd nd nd 24 ± 2 a 24 c nd nd nd nd nd 350 ± 19 bc nd 1440 ± 171 c 141 ± 12 ab 119 ± 13 a 2050 c
trace nd nd nd nd nd 35 ± 2 a 35 c 65 ± 4 a 54 ± 4 a 63 ± 3 b nd 90 ± 4 b 272 b 499 ± 14 b nd 2205 ± 231 a 165 ± 10 a 123 ± 11 a 2992 b
nd nd nd nd nd nd nd nd 20 ± 2 c 15 ± 1 c nd nd 35 e 218 ± 12 c nd 1257 ± 22 cd 77 ± 4 c 46 ± 2 c 1598 d
trace nd 282 ± 11 a nd nd nd trace 282 a 51 ± 1 b 34 ± 1 b 96 ± 2 a nd 171 ± 6 a 352 a 2665 ± 146 a nd 1060 ± 51 d trace 92 ± 7 b 3817 a
nd nd 59 ± 5 b nd nd 137 ± 6 nd 196 b nd 14 ± 1 d 16 ± 2 c nd 27 ± 4 c 57 d nd nd 975 ± 101 d 110 ± 14 b 90 ± 12 b 1175 e
nd nd 35 ± 5 c nd nd nd nd 35 c 26 ± 1 c 18 ± 1 cd 67 ± 1 b nd 17 ± 1 d 128 c nd nd 1812 ± 35 b 133 ± 14 ab 43 ± 2 c 1988 cd
DM: dry matter; 1-O-caffeoylquinic acid (Rt = 9.23 min); 3-O-caffeoylquinic acid (Rt = 10.8 min); 5-O-caffeoylquinic acid (or chlorogenic acid) (Rt = 15.9 min); 4-O-caffeoylquinic acid (Rt = 17.8 min); Luteolin 7-O-rutinoside (Rt = 25.2 min); 3,4-di-O-caffeoylquinic acid (Rt = 25.4 min); Luteolin 7-O-glucoside (Rt = 26.0 min); Luteolin 7-O-glucuronide (Rt = 26.3 min); 3,5-di-O-caffeoylquinic acid (Rt = 27.1 min); 1,5-di-O-caffeoylquinic acid (Rt = 27.6 min); Apingenin 7-O-rutinoside (Rt = 27.8 min); Apigenin 7-O-glucoside (Rt = 28.7 min); Apigenin 7-O-glucuronide (Rt = 29.2 min); Luteolin malonylglucoside (Rt = 29.7 min); 4,5-di-O-caffeoylquinic acid (Rt = 31.7 min); Apigenin malonylglucoside (Rt = 32.1 min); Luteolin (Rt = 35.0 min); Apigenin (Rt = 39.2 min); and Hesperetin (Rt = 40.1 min). Rt, indicated in brackets, means retention time value; nd: not detected.
3.4. Antioxidant activity
4. Discussion and conclusions
Antioxidant activity, expressed as percentage inhibition of DPPH radical, varied amongst cultivars and plant parts. With regard to the whole head, ‘Violetto di Sicilia clone 4/8’ had the highest antioxidant activity, whereas ‘Tempo’ revealed the lowest value (Fig. 1). A strongly significant (P ≤ 0.001) positive correlation (r = 0.37) was detected between the antioxidant activity and total polyphenol content both amongst cultivars and plant parts. Antioxidant activity in the floral stem was significantly higher than in the inner bracts, receptacle and outer bracts (Fig. 2).
In the present work, we reported the variation of polyphenol content and antioxidant activity of a large germplasm collection (17 cultivars) of globe artichoke in relation to the different plant parts (floral stem, receptacle, inner and outer bracts). In addition, we also investigated the effects of harvest time (winter and spring) on total polyphenol content. Firstly, a significant influence of cultivar was found on the content of both total polyphenols and individual polyphenols as previously demonstrated in other crops, including potato (Al-Weshahy & Rao, 2009), faba bean (Chaieb, González, López-Mesas, Bouslama, & Valiente, 2011) and tomato
Table 5 Polyphenol (mg kg− 1 DM) content of inner bracts in relation to cultivar. Different letters amongst cultivars for each compound indicate statistically significant differences between means (P ≤ 0.05). Compound
1-O-caffeoylquinic acid a 3-O-caffeoylquinic acid 5-O-caffeoylquinic acid 3,4-di-O-caffeoylquinic acid 3,5-di-O-caffeoylquinic acid 1,5-di-O-caffeoylquinic 4,5-di-O-caffeoylquinic Total caffeoylquinic acid Luteolin 7-O-rutinoside Luteolin 7-O-glucoside Luteolin 7-O-glucuronide Luteolin malonylglucoside Luteolin Total luteolin Apigenin 7-O-rutinoside Apigenin 7-O-glucoside Apigenin 7-O-glucuronide Apigenin malonylglucoside Apigenin Total apigenin
Cultivar Camard
Camerys
Empolese
Locale di Mola
Opal
Spinoso di Palermo
nd nd nd nd nd 189 ± 23 d 26 ± 2 b 215 e nd nd 12 ± 1 d nd 15 ± 2 c 27 e nd 81 ± 8 b 1847 ± 211 c 183 ± 21 b 294 ± 34 a 2405 b
trace nd 105 ± 10 d nd nd 276 ± 24 d 31 ± 1 b 412 d 31 ± 1 b 19 ± 1 79 ± 6 b nd 24 ± 2 bc 153 c nd 111 ± 11 ab 3901 ± 238 a 187 ± 10 b 235 ± 13 bc 4434 a
nd nd nd nd nd nd nd – nd nd nd nd nd – 199 ± 10 nd 1873 ± 102 bc 61 ± 3 d 133 ± 7 d 2266 b
30 ± 1 b nd 686 ± 29 b nd nd 925 ± 37 b 49 ± 2 a 1690 b 46 ± 3 a nd 75 ± 4 b nd 102 ± 7 a 223 b nd 130 ± 10 a 2027 ± 106 bc 106 ± 5 c 217 ± 13 c 2480 b
trace nd 233 ± 13 c nd nd 595 ± 39 c 43 ± 3 a 871 c nd nd 31 ± 2 c nd 33 ± 1 b 64 d nd nd 1753 ± 134 c 174 ± 13 b 265 ± 20 ab 2192 b
81 ± 0.3 a nd 1246 ± 23 a nd nd 2071 ± 38 a trace 3398 a 36 ± 1 b nd 191 ± 2 a nd 32 ± 1 b 259 a nd nd 2261 ± 27 b 254 ± 17 a 64 ± 2 e 2579 b
DM: dry matter and nd: not detected. a See note in Table 6 for the retention time values of the identified compounds.
S. Lombardo et al. / Food Research International 46 (2012) 544–551
549
Table 6 Polyphenol (mg kg− 1 DM) content of receptacle in relation to cultivar. Different letters amongst cultivars for each compound indicate statistically significant differences between means (P ≤ 0.05). Compound
Cultivar
a
1-O-caffeoylquinic acid 3-O-caffeoylquinic acid 5-O-caffeoylquinic acid 3,4-di-O-caffeoylquinic acid 3,5-di-O-caffeoylquinic acid 1,5-di-O-caffeoylquinic 4,5-di-O-caffeoylquinic Total caffeoylquinic acid Luteolin 7-O-rutinoside Luteolin 7-O-glucoside Luteolin 7-O-glucuronide Luteolin malonylglucoside Luteolin Total luteolin Apigenin 7-O-rutinoside Apigenin 7-O-glucoside Apigenin 7-O-glucuronide Apigenin malonylglucoside Apigenin Total apigenin
Camard
Camerys
Empolese
Locale di Mola
Opal
Spinoso di Palermo
trace nd 116 ± 4 d nd nd 530 ± 28 d nd 646 d 24 ± 1 50 ± 2 b 112 ± 5 c nd 88 ± 4 a 274 d nd 422 ± 29 b 1920 ± 98 bc 364 ± 16 a 168 ± 8 a 2874 bc
trace nd 91 ± 5 d nd nd 500 ± 10 d 30 ± 1 621 d nd 567 ± 37 a nd nd 48 ± 3 c 615 a nd 288 ± 28 c 2686 ± 222 a 98 ± 4 c 78 ± 5 b 3150 ab
nd nd 165 ± 18 d nd nd 393 ± 54 d nd 558 d nd nd 60 ± 7 d nd 4 ± 0.4 d 64 c nd 121 ± 12 d 2215 ± 241 b 105 ± 10 c 33 ± 4 c 2474 c
trace nd 560 ± 39 c nd nd 761 ± 53 c trace 1321 c nd nd nd nd nd – nd 93 ± 6 d 902 ± 68 d 103 ± 6 c 12 ± 1 d 1110 e
61 ± 7 b trace 758 ± 97 b nd nd 1818 ± 99 b nd 2637 b nd 85 ± 4 b 272 ± 13 b nd 60 ± 4 b 417 c nd 591 ± 34 a 2633 ± 125 a 217 ± 8 b 160 ± 9 a 3601 a
108 ± 1 a nd 976 ± 10 a nd nd 2375 ± 33 a nd 3459 a nd nd 506 ± 13 a nd trace 506 b nd 324 ± 8 c 1559 ± 45 c trace trace 1883 d
DM: dry matter and nd: not detected. a See note in Table 6 for the retention time values of the identified compounds.
(Vallerdú-Queralt et al., 2011). From a quantitative point of view, we highlighted that the total polyphenol content of the whole globe artichoke head ranged from 1.2% to 5.9%, as measured on a DM basis. Cultivars with a total polyphenol content within the upper part of this range (‘Tema 2000’, ‘Nobre’ and ‘Violetto di Sicilia clone 4/8’) are probably best suited for the fresh consumption. Amongst them, ‘Violetto di Sicilia clone 4/8’ had also the major antioxidant activity and, hence, it may be also a potential target for the industrial recovery of natural antioxidants aimed to replace the synthetic ones. On the other hand, high levels of polyphenols can be undesirable, since they are associated with either enzymatically and nonenzymatically oxidative browning reactions (Lattanzio, Cardinali, Di Venere, Linsalata, & Palmieri, 1994; Peschel et al., 2006). Therefore, ‘Tempo’, characterised by a low content of total polyphenols, resulted more suitable for food processing in virtue of its presumable less
proneness to brown during handling and storage (Lattanzio, 2003). In addition, the data about the polyphenol profile of six cultivars (i.e. ‘Camard’, ‘Camerys’, ‘Empolese’, ‘Locale di Mola’, ‘Opal’ and ‘Spinoso di Palermo’), not previously analysed, combined with those of our previous studies (Lombardo et al., 2010; Pandino et al., 2011b), may allow to select cultivars for more specific pharmaceutical applications (extraction of specific polyphenols). Regardless of cultivar, as already observed (Fratianni, Tucci, De Palma, Pepe, & Nazzaro, 2007; Lombardo, Pandino, Mauro, & Mauromicale, 2009; Lombardo et al., 2010; Pandino et al., 2011a,b), individual polyphenols were preferentially accumulated in specific parts of the plant, presumably related to their role (Pandino et al., 2011a,b). In particular, the floral stem was the best source of caffeoylquinic acids, mainly chlorogenic acid (5-O-caffeoylquinic acid) and 1,5-di-O-caffeoylquinic acid. Thus, this
Table 7 Polyphenol (mg kg− 1 DM) content of floral stem in relation to cultivar. Different letters amongst cultivars for each compound indicate statistically significant differences between means (P ≤ 0.05). Compound
1-O-caffeoylquinic acid a 3-O-caffeoylquinic acid 5-O-caffeoylquinic acid 3,4-di-O-caffeoylquinic acid 3,5-di-O-caffeoylquinic acid 1,5-di-O-caffeoylquinic 4,5-di-O-caffeoylquinic Total caffeoylquinic acid Luteolin 7-O-rutinoside Luteolin 7-O-glucoside Luteolin 7-O-glucuronide Luteolin malonylglucoside Luteolin Total luteolin Apigenin 7-O-rutinoside Apigenin 7-O-glucoside Apigenin 7-O-glucuronide Apigenin malonylglucoside Apigenin Total apigenin
Cultivar Camard
Camerys
Empolese
Locale di Mola
Opal
Spinoso di Palermo
nd nd 337 ± 24 d nd nd 854 ± 64 d trace 1191 e 38 ± 2 b 24 ± 1 b nd 33 ± 2 c 18 ± 1 113 b nd trace nd trace trace –
46 ± 6 b nd 356 ± 11 d nd nd 719 ± 23 d trace 1121 e 50 ± 3 a 37 ± 2 b nd 51 ± 7 b nd 138 a nd nd nd nd nd –
nd trace 932 ± 28 c nd nd 1223 ± 50 d nd 2155 d 34 ± 1 b 26 ± 1 b nd nd nd 60 c nd nd 177 ± 15 trace nd 177
trace 44 ± 2 1787 ± 176 b 131 ± 5 a 178 ± 14 a 3364 ± 206 b 52 ± 4 5556 b nd 28 ± 3 b nd 31 ± 3 c nd 59 c nd nd nd nd nd –
53 ± 2 b trace 1045 ± 14 c 44 ± 5 b 42 ± 3 b 2193 ± 270 c trace 3377 c nd 67 ± 8 a nd 72 ± 7 a nd 139 a nd nd nd trace nd –
83 ± 4 a nd 2877 ± 148 a nd nd 4255 ± 215 a nd 7215 a 46 ± 2 a nd nd nd nd 46 c nd nd nd nd nd –
DM: dry matter and nd: not detected. a See note in Table 6 for the retention time values of the identified compounds.
550
S. Lombardo et al. / Food Research International 46 (2012) 544–551
Fig. 1. Antioxidant activity (AA) of the whole globe artichoke head in relation to cultivar. Different letters indicate statistically significant differences between means (P ≤ 0.05).
plant part, generally discarded as waste matter, may represent an unexploited source of natural antioxidants hitherto (Larossa, Llorach, Espin, & Tomas-Barberan, 2002), whose industrial recovery could represent an added economic value for the producers and processors (Peschel et al., 2006). According to our data, the use of ‘Spinoso di Palermo’ and ‘Locale di Mola’ floral stems (rich in caffeoylquinic acids), together with those of ‘Nobre’ and ‘Violetto di Sicilia’ (Lombardo et al., 2009; Lombardo et al., 2010; Pandino et al., 2011a), is suggested for the extraction of natural antioxidants. The receptacle, considered as the main edible part of the plant, showed an intermediate level of total polyphenols between the floral stem and bracts. Besides having a good content of total caffeoylquinic acids, this head part was also rich in total apigenin (mainly apigenin 7-O-glucuronide) and luteolin. This result is important since flavones such as apigenin exhibit potent biological effects in vitro and in vivo (Aljancic et al., 1999; Birt, Mitchell, Gold, Pour, & Pinch, 1997; Rossoni, Grande, Galli, & Visioli, 2005; Van Acker et al., 1996). In this respect, the receptacles of ‘Camerys’ and ‘Opal’ proved to be an interesting source of apigenin derivatives, mainly apigenin 7-O-glucuronide, after ‘Romanesco C3’ and ‘Concerto’ (Lombardo et al., 2010). Furthermore, the inner bracts,
the richest in total apigenin (2726 mg kg− 1 DM, on average of cultivars) amongst plant parts analysed, might be revaluated since, if properly prepared, are also edible. Thus, the presence of high amount of polyphenols in the edible part of globe artichoke plant, combined with the enhanced interest for ‘functional’ foods by consumers, may encourage the globe artichoke consumption on a wider scale. As highlighted by the results acquired, although the level of polyphenols is strictly under genetic control (Moglia et al., 2008), it could be subjected to marked and significant variations also in relation to harvest time. In particular, the weather conditions recorded in spring time (data not shown), represented mainly by the highest average maximum temperatures, are presumably more favourable to polyphenol bio-synthesis in both cultivars studied (i.e. ‘Romanesco clone C3’ and ‘Tema 2000’). This trend, for ‘Romanesco clone C3’, was also found for the individual polyphenols (Lombardo et al., 2010). In conclusion, probably the most important outcomes of this study were the comparison of a large number of globe artichoke cultivars for the total polyphenol content and the evaluation of the polyphenol profile of six cultivars not previously analysed. Our results, including
90
a
AA (%)
89
88
b
b
b
87
86
85
outer bracts
inner bracts
receptacle
floral stem
Fig. 2. Antioxidant activity (AA) of globe artichoke in relation to the plant part (values are the mean of measurements on cultivars). Different letters indicate statistically significant differences between means (P ≤ 0.05).
S. Lombardo et al. / Food Research International 46 (2012) 544–551
those of our previous works (Lombardo et al., 2010; Pandino et al., 2011a), demonstrated the high level of biodiversity in the globe artichoke germplasm for the amount of polyphenols. This important nutritional and technological characteristic may preserve cultivars from genetic erosion through their selection for a specific end-use (fresh market, food processing, pharmaceutical applications, etc.). On the other side, we also suggest that, considering the value – both nutritional and pharmaceutical – of polyphenols, it should be the case to initiate a breeding programme in order to improve the total polyphenol content of the globe artichoke head, mainly for cultivars destined for fresh consumption. An interesting aspect for future research will be to ascertain the variation of polyphenol content in response to the other factors (i.e. cultivation environment, crop management practices, etc.) that may affect polyphenol biosynthesis and accumulation in globe artichoke plants, as well as to clarify the interaction between gene expression and the biosynthesis of polyphenols. Acknowledgement This research was partially supported by the CAR-VARVI project (MiPAF). The authors are grateful to Mr. Antonino Russo for his agronomical assistance. References Alamanni, M. C., & Cossu, M. (2003). Antioxidant activity of the extracts of the edible part of artichoke (Cynara scolymus L.) var. Spinoso sardo. Italian Journal of Food Science, 15, 187–195. Aljancic, I., Vajs, V., Menkovic, N., Karadzic, I., Juranic, N., Milosavljevic, S., et al. (1999). Flavones and sesquiterpene lactones from Achillea atrata subsp. multifida: Antimicrobial activity. Journal of Natural Products, 62, 909–911. Al-Weshahy, A., & Rao, A. V. (2009). Isolation and characterization of functional components from peel samples of six potatoes varieties growing in Ontario. Food Research International, 42, 1062–1066. Beckman, C. H. (2000). Phenolic-storing cells: Keys to programmed cell death and periderm formation in wilt disease resistance and in general defence responses in plants? Physiological and Molecular Plant Pathology, 57, 101–110. Birt, D. F., Mitchell, D., Gold, B., Pour, P., & Pinch, H. C. (1997). Inhibition of ultraviolet light-induced skin carcinogenesis in SKH-1 mice by apigenin, a plant flavonoid. Anticancer Research, 17, 85–91. Brand-Williams, W., Cuvelier, M. E., & Berset, C. (1995). Use of a free radical method to evaluate antioxidant activity. Lebensmittel-Wissenschaft und —Technologie, 22, 25–30. Brat, P., Georgé, S., Bellamy, A., Du Chaffaut, L., Scalbert, A., Mennen, L., et al. (2006). Daily polyphenol intake in France from fruit and vegetables. Journal of Nutrition, 136, 2368–2373. Bravo, L. (1998). Polyphenols: Chemistry, dietary sources, metabolism, and nutritional significance. Nutrition Reviews, 56, 317–333. Chaieb, N., González, J. L., López-Mesas, M., Bouslama, M., & Valiente, M. (2011). Polyphenols content and antioxidant capacity of thirteen faba bean (Vicia faba L.) genotypes cultivated in Tunisia. Food Research International, 44, 970–977. Curadi, M., Ceccarelli, N., Graifenberg, A., & Picciarelli, P. (2004). Composti ad attività antiossidante nei capolini di carciofo: differenze varietali. Italus Hortus, 11, 81–84. FAO (2009). http://www.faostat.fao.org. Fratianni, F., Tucci, M., De Palma, M., Pepe, R., & Nazzaro, F. (2007). Polyphenolic composition in different parts of some cultivars of globe artichoke (Cynara cardunculus L. var. scolymus (L.) Fiori). Food Chemistry, 104, 1282–1286. IUPAC (1976). Nomenclature of cyclitols. Biochemical Journal, 153, 23–31. Kähkönen, M. P., Hopia, A. I., Vuorela, H. J., Rauha, J. P., Pihlaja, K., & Kujala, T. S. (1999). Antioxidant activity of plant extracts containing phenolic compounds. Journal of Agricultural and Food Chemistry, 47, 3954–3962.
551
Larossa, M., Llorach, R., Espin, J. C., & Tomas-Barberan, F. A. (2002). Increase of antioxidant activity of tomato juice upon functionalisation with vegetable byproduct extracts. Lebensmittel-Wissenschaft und —Technologie, 35, 532–542. Lattanzio, V. (2003). Bioactive polyphenols: Their role in quality and storability of fruit and vegetables. Journal of Applied Botany, 77, 128–146. Lattanzio, V., Cardinali, A., Di Venere, D., Linsalata, V., & Palmieri, S. (1994). Browning phenomena in stored artichoke (Cynara scolymus L.) heads: Enzymatic or chemical reactions? Food Chemistry, 50, 1–7. Lattanzio, V., Kroon, P. A., Linsalata, V., & Cardinali, A. (2009). Globe artichoke: a functional food and source of nutraceutical ingredients. Journal of Functional Foods, 1, 131–144. Lombardo, S., Pandino, G., Mauro, R., & Mauromicale, G. (2009). Variation of phenolic content in globe artichoke in relation to biological, technical and environmental factors. Italian Journal of Agronomy, 4, 181–189. Lombardo, S., Pandino, G., Mauromicale, G., Knödler, M., Carle, R., & Schieber, A. (2010). Influence of genotype, harvest time and plant part on polyphenolic composition of globe artichoke [Cynara cardunculus L. var. scolymus (L.) Fiori]. Food Chemistry, 119, 1175–1181. Manach, C., Scalbert, A., Morand, C., Rémésy, C., & Jimènez, L. (2004). Polyphenols: Food sources and bioavailability. American Journal of Clinical Nutrition, 79, 727–747. Mauromicale, G., & Ierna, A. (2000). Characteristics of heads of seed-grown globe artichoke [Cynara cardunculus L. var. scolymus (L.) Fiori] as affected by harvest period, sowing date and gibberellic acid. Agronomie, 20, 197–204. Moglia, A., Lanteri, S., Comino, C., Acquadro, A., De Vos, R., & Beekwilder, J. (2008). Stress-induced biosynthesis of dicaffeoylquinic acids in globe artichoke. Journal of Agricultural and Food Chemistry, 56, 8641–8649. Pandino, G., Courts, F. L., Lombardo, S., Mauromicale, G., & Williamson, G. (2010). Caffeoylquinic acids and flavonoids in the immature inflorescence of globe artichoke, wild cardoon, and cultivated cardoon. Journal of Agricultural and Food Chemistry, 58, 1026–1031. Pandino, G., Lombardo, S., Mauromicale, G., & Williamson, G. (2011a). Phenolic acids and flavonoids in leaf and floral stem of cultivated and wild Cynara cardunculus L. genotypes. Food Chemistry, 126, 417–422. Pandino, G., Lombardo, S., Mauromicale, G., & Williamson, G. (2011b). Profile of polyphenols and phenolic acids in bracts and receptacles of globe artichoke (Cynara cardunculus var. scolymus) germplasm. Journal of Food Composition and Analysis, 24, 148–153. Peschel, W., Sànchez-Rabaneda, F., Diekmann, W., Plescher, A., Gartzìa, I., Jimènez, D., et al. (2006). An industrial approach in the search of natural antioxidants from vegetable and fruit wastes. Food Chemistry, 97, 137–150. Racchi, M., Daglia, M., Lanni, C., Papetti, A., Govoni, S., & Gazzani, G. (2002). Antiradical activity of water soluble components in common diet vegetables. Journal of Agricultural and Food Chemistry, 50, 1272–1277. Rossoni, G., Grande, S., Galli, C., & Visioli, F. (2005). Wild artichoke prevents the ageassociated loss of vasomotor function. Journal of Agricultural and Food Chemistry, 53, 10291–10296. Scalbert, A., & Williamson, G. (2000). Dietary intake and bioavailability of polyphenols. Journal of Nutrition, 130, 2073S–2085S. Schütz, K., Kammerer, D., Carle, R., & Schieber, A. (2004). Identification and quantification of caffeoylquinic acids and flavonoids from artichoke (Cynara scolymus L.) heads, juice, and pomace by HPLC-DAD-ESI/MSn. Journal of Agricultural and Food Chemistry, 52, 4090–4096. Shahidi, F., & Naczk, M. (1995). Food phenolics: Sources, chemistry, effects and applications. Lancaster: Technomic Publishing Company. Singleton, V. L., & Rossi, J. A. J. R. (1965). Colorimetry of total phenolics with phosphomolybdic phosphotungstic acid reagents. American Journal of Enology and Viticulture, 16, 144–158. Vallerdú-Queralt, A., Medina-Remón, A., Martínez-Huélamo, M., Jáuregui, O., AndresLacueva, C., & Lamuela-Raventos, R. M. (2011). Phenolic profile and hydrophilic antioxidant capacity as chemotaxonomic markers of tomato varieties. Journal of Agricultural and Food Chemistry, 59, 3994–4001. Van Acker, S. A. B. E., Van Den Berg, D., Tromp, M. N. J. L., Griffioen, D. E., Van Bennekom, W. P., Van Der Vijgh, W. J. F., et al. (1996). Structural aspects of antioxidant activity of flavonoids. Free Radical Biology & Medicine, 20, 331–342. Zdunczyk, Z., Frejnagela, S., Wróblewska, M., Juśkiewicz, J., Oszmiańskib, J., & Estrella, I. (2002). Biological activity of polyphenol extracts from different plant sources. Food Research International, 35, 183–186.
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Variation of polyphenols in a germplasm collection of globe artichoke Sara Lombardo a, Gaetano Pandino a, Anita Ierna b, Giovanni Mauromicale a,⁎ a b
Dipartimento di Scienze delle Produzioni Agrarie ed Alimentari, Università degli Studi di Catania, via Valdisavoia 5, 95123 Catania, Italy Istituto per i Sistemi Agricoli e Forestali del Mediterraneo, CNR, Sezione di Catania, Str.le V. Lancia, Zona Industriale; Blocco Palma I 95121 Catania, Italy
a r t i c l e
i n f o
Article history: Received 26 January 2011 Accepted 16 June 2011 Keywords: Cynara cardunculus var. scolymus Polyphenols Antioxidant activity Germplasm Plant part Harvest time
a b s t r a c t Globe artichoke, a crop native to the Mediterranean Basin, is rich in polyphenols whose health-promoting properties have been well documented in literature. Here, we reported the variation of polyphenol content and antioxidant activity in plant parts (floral stem, receptacle, inner and outer bracts) of 17 cultivars. Our objectives were also to evaluate the influence of harvest time (winter and spring) on total polyphenol content and to assess the polyphenol composition by HPLC in six cultivars not previously analysed. The total content and profile of polyphenols were significantly different amongst cultivars and plant parts. ‘Tema 2000’, ‘Nobre’ and ‘Violetto di Sicilia clone 4/8’ had the highest level of total polyphenol content, whilst ‘Camerys’ and ‘Tempo’ had the lowest. Polyphenols resulted more abundant in the floral stem and receptacle. These were, respectively, rich in caffeoylquinic acids and apigenin derivatives. Each cultivar preferentially accumulated polyphenols in specific plant parts and, hence, may have a specific end-use based on its polyphenol content. In this view, the high level of total polyphenols in the receptacles of ‘Tema 2000’, ‘Opal’ and ‘Nobre’ makes them more suitable for the fresh consumption, whereas the floral stems of ‘Violetto di Sicilia clone 4/8’, ‘Nobre’ and ‘Tema 2000’ are suggested for the exploitation as source of natural antioxidants. In addition, the cultivar-dependency of both polyphenol content and antioxidant activity of globe artichoke extracts led to foresee the possible manipulation by specific breeding and selection programmes in order to improve the health-beneficial properties of globe artichoke head. Our findings prove also the influence of harvest time on the polyphenol content and thus suggest giving specific consideration to the other factors (e.g. temperature and photoperiod) that may affect polyphenol biosynthesis and accumulation in globe artichoke plant. © 2011 Elsevier Ltd. All rights reserved.
1. Introduction Polyphenols are a well studied group of secondary metabolites widely distributed throughout the plant kingdom (Kähkönen et al., 1999). Structurally, they range from simple molecules to highly polymerised compounds (Manach, Scalbert, Morand, Rémésy, & Jimènez, 2004). They are involved in numerous physiological and biochemical processes of the plant, including defence against pathogens and parasites, wound repair and protection from atmospheric pollution and extreme temperatures (Beckman, 2000; Bravo, 1998). Some polyphenols have been also associated with the sensory, nutritional and medicinal properties of particular foodstuffs (Scalbert & Williamson, 2000; Shahidi & Naczk, 1995; Zdunczyk et al., 2002). In recent years, the globe artichoke [Cynara cardunculus L. var. scolymus (L.) Fiori= C. scolymus L.] has got a renewed interest as source of bioactive compounds (Lattanzio, Kroon, Linsalata, & Cardinali, 2009). It is a herbaceous crop native to the Mediterranean Basin, where its
Abbreviations: CAE, chlorogenic acid equivalent; DM, dry matter; DPPH, 2,2-diphenyl1-picrylhydrazyl; FM, fresh matter; L/D, length/diameter ratio of head; TPC, total polyphenol content. ⁎ Corresponding author. Tel.: + 39 095 234 409; fax: + 39 095 234 449. E-mail address: [email protected] (G. Mauromicale). 0963-9969/$ – see front matter © 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodres.2011.06.047
commercial production gives a significant contribution to the agricultural economy. Today, globe artichoke heads production is widely diffused all over the world (133 kha), even if it is concentrated in Southern Europe with Italy as the leading producer (about 487 kt per year), followed by Spain and France (about 199 and 45 kt per year, respectively). Globe artichoke is also cultivated in the Near East, North Africa, South America, United States (California) and recently its cultivation is spreading in China (10 kha) and Peru (8 kha) (FAO, 2009). The edible part of the plant is the enlarged receptacle and the tender thickened bract bases of the head (capitulum), which is the immature Asteraceae (Compositae) inflorescence, used worldwide as both a fresh and canned delicacy. Furthermore, globe artichoke has a healthy image also related to the polyphenols present in the leaves and inflorescences, with phenolic acids (mono- and di-caffeoylquinic acids) and flavonoids (luteolin and apigenin derivatives) as the major bioactive substances (Lattanzio et al., 2009; Lombardo et al., 2010; Pandino, Lombardo, Mauromicale, & Williamson, 2011a,b; Schütz, Kammerer, Carle, & Schieber, 2004). In literature, previous works extensively studied the qualitative and quantitative polyphenol profiles of the globe artichoke, but most of them examined unknown cultivars obtained from local markets rather than from experimental fields (Brat et al., 2006; Racchi et al., 2002) or were limited to few cultivars (Alamanni & Cossu, 2003; Curadi,
S. Lombardo et al. / Food Research International 46 (2012) 544–551
Ceccarelli, Graifenberg, & Picciarelli, 2004). In recent years we have investigated the polyphenol profile of several globe artichoke cultivars maintained in the germplasm collection at Catania University (Lombardo et al., 2010; Pandino, Courts, Lombardo, Mauromicale, & Williamson, 2010; Pandino et al., 2011a,b). Screening of further globe artichoke cultivars relative to polyphenol content is of particular interest for the biodiversity preservation. In fact, this important nutritional and technological characteristic could be a natural tool to bestow a specific end-use on cultivars. At present, the germplasm of globe artichoke is characterised by a great number of commercial and local cultivars, different for biological, morphological and qualitative traits. Our intention was to promote cultivars with high polyphenol content of the receptacle (edible fraction) for fresh consumption and to consider those with higher polyphenol amounts in the waste (floral stem and bracts) for the recovery of these bio-compounds. On the other side, cultivars characterised by lower levels of polyphenols would be predestined for minimally processed foods. In this light, the aim of the present study was to evaluate the total polyphenol content and antioxidant activity of seventeen globe artichoke cultivars (both widely cultivated, landraces and novel ‘seed’ propagated cultivars) in relation to plant part (floral stem, receptacle, inner and outer bracts) and harvest time (winter and spring). Here, for the first time, we characterised the polyphenol profile of six cultivars, aimed to provide further information about the available globe artichoke germplasm and to better exploit this as potential natural source of these phytochemicals.
2. Material and methods 2.1. Site, soil and climate of field experiments Field experiments were conducted during 2006–2007 at the experimental station of Catania University on Catania Plain (37°25′N, 15°30′E, 10 m a.s.l.), in a typic and/or vertic xerochrepts soil (USDA, Soil Taxonomy). The Catania Plain is a typical area for globe artichoke cultivation in the Mediterranean Basin. The soil characteristics were: clay 45%, silt 28%, sand 27%, organic matter 1%, total nitrogen 0.1%, available P2O5 10 ppm, exchangeable K2O 210 ppm, and pH 7.2. The local climate is semi-arid-Mediterranean, characterised by mild rainy winters and hot, rainless summers. The mean 30-year maximum monthly temperature ranges between 14.8 °C (January) and 30.6 °C (July), and the minimum temperature between 7.8 °C (January) and 22.3 °C (August).
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2.2. Plant material, experimental design and management practices Seventeen globe artichoke cultivars (Table 1) were manually planted in the form of either semi-dormant offshoots (“ovoli”) or seeds (achenes) in August 2006. The plant material was arranged in a randomised block experimental design with four replications, adopting a planting density of 1.0 plant m− 2 (equivalent to a within row plantto-plant spacing of 0.80 m apart, and a row-to-row spacing of 1.25 m). Each experimental unit consisted of 10 plants. A typical fertiliser programme (200 kg N, 80 kg P2O5 and 100 kg K2O per ha) was applied. Drip irrigation was carried out during the summer, when the accumulated daily evaporation reached 35 mm (equivalent to 100% of maximum evapotranspiration). Pest control followed standard commercial practice. No gibberellic acid was applied to the plants during the crop cycle. 2.3. Morphological description of the cultivars At least 5 heads per replicate were harvested, with the floral stem including 2–3 leaves, at the usual marketing stage and regardless of size. At this stage, the length of the central floral buds was about 2 mm (Mauromicale & Ierna, 2000). After harvesting, the floral stem was removed from the head by cutting 0.5 cm under the receptacle. All heads were weighed and their maximum diameter and length measured. Head length/diameter ratio (L/D ratio), an important index of its shape, was calculated. L/D ratio is a relatively constant trait of each cultivar, varying from 0.9 to 1.1 and ≥1.2 in spherical/sub-spherical and in long shaped types, respectively (Mauromicale & Ierna, 2000). The colour of the outer and inner bracts was recorded on the basis of visual evaluation. 2.4. Sample preparation The heads harvested were mixed, washed with tap water and separated into outer bracts (~ 15 external bracts), inner bracts (remaining bracts) and receptacle. The floral stem, previously separated from its head, was also cleaned and dried. Each part of the inflorescence, including the floral stem, was sliced into small pieces (b0.5 cm), immediately blended using a domestic food processor at 0 °C (Kenwood multipro, Milan, Italy). Finally, an amount of each fraction was freezedried using a Christ freeze drier (Osterode am Harz, Germany), divided into three replicates and stored at −20 °C until HPLC analysis, whereas the remaining portion was directly used to analyse the total polyphenol
Table 1 Main head characteristics of globe artichoke cultivars under study. Different letters within each column indicate statistically significant differences between means (P ≤ 0.05). Cultivar
Fresh weight (g)
L/D
1. Blanc Hyérois 2. Camard 3. Camerys 4. Concerto 5. Empolese 6. Harmony F1 7. Locale di Mola 8. Madrigal F1 9. Nobre 10. Opal 11. Romanesco clone C3 12. Spinoso di Palermo 13. Tema 2000 14. Tempo 15. Tondo di Paestum 16. Violetto di Provenza 17. Violetto di Sicilia clone 4/8 Mean CV (%)
197 186 173 201 216 225 163 219 147 195 144 153 167 176 210 125 117 177 19
1.20 0.89 0.98 1.25 1.20 1.15 1.42 1.15 1.03 1.20 1.05 1.48 1.25 1.30 1.00 1.45 1.50 1.21 15
ac bf dg ad ab a eg a gi ac gi fh eg cg ac hi i
de h g cd de e b e fg de f ab cd c fg ab a
Colour of outer bracts
Colour of inner bracts
Green Green with purple shades Green with purple shades Deep purple Purple with green shades Green Purple with green shades Green Green Purple with green shades Purple with green shades Green with purple shades or purple with green shades Deep purple Purple with green shades Purple with light green shades Purple with green shades Green with purple shades – –
Yellow-greenish Yellow-greenish with purple shades Yellow-purple Yellowish-green Yellow with purple shades Yellow Yellow with purple shades Yellow Yellow Yellowish-green Yellow-greenish with purple shades Yellowish-green with purple shades Yellow with purple shades Yellow-purple Yellow-purple Yellow-purple Yellow-greenish – –
Cultivar 12 is spiny, cultivars 6, 10 and 13 are mucronate and the remaining are spineless; L/D: length/diameter ratio of head; and CV: coefficient of variation.
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content and antioxidant activity. The heads of two cultivars (‘Romanesco clone C3’ and ‘Tema 2000’) were collected in winter and spring, aimed at studying the influence of harvest time on the total polyphenol content. 2.5. Chemicals Reagents and solvents of analytical grade, used for total polyphenol content and antioxidant activity assays, were purchased from Sigma Aldrich (Milan, Italy), whilst those for HPLC analysis were obtained from VWR (Milan, Italy) and were of analytical or HPLC grade. Apigenin-7-Oglucoside, apigenin-7-O-rutinoside, apigenin, luteolin-7-O-glucoside, luteolin, 5-O-caffeoylquinic acid (chlorogenic acid) and hesperetin were obtained from Extrasynthese (Lyon, France), cynarin (1,3-di-O-caffeoylquinic acid) was from Applichem GmbH (Darmstadt, Germany), and butylated hydroxytoluene (BHT) was purchased from Sigma Aldrich (Milan, Italy). Deionised water was used throughout. 2.6. Analysis of total polyphenol content For the extraction of total polyphenols, 5 g per replicate was treated with 50 mL of methanol containing 1% hydrochloric acid, blended for 2 min in an Ultra-Turrax T18 (Janke & Kunkel Ika-Labortechnik, Staufen, Germany) and stirred at room temperature for 1 h. The filtrate (through Whatman No. 4 filter paper) was stored at −20 °C until required. The Folin–Ciocalteu assay (Singleton & Rossi, 1965) was used to quantify the total polyphenol content (TPC). The absorbance was measured at 760 nm using a Shimadzu 1601 UV–Visible spectrophotometer (Tokyo, Japan). The total polyphenol content was determined on the basis of a standard calibration curve generated with known amounts of chlorogenic acid and expressed as grammes of chlorogenic acid equivalent (CAE) per kilogramme on both fresh matter (FM) and dry matter (DM) bases. Data are mean of three independent experiments (n = 3).
(IUPAC, 1976). Luteolin-7-O-glucuronide, luteolin-7-O-rutinoside and luteolin malonylglucoside were quantified at 350 nm using luteolin-7O-glucoside as a reference. Finally, apigenin-7-O-glucuronide and apigenin malonylglucoside were estimated at 310 nm, using apigenin7-O-glucoside as a reference. All peak areas and retention times were expressed relative to the internal standard of hesperetin added prior to extraction of samples. All data are presented as mean± standard deviation of three individual experiments (n = 3), and expressed as mg/kg of dry matter (DM). 2.8. Determination of antioxidant activity The antioxidant activity of the extracts was evaluated as percentage inhibition of DPPH radical (Brand-Williams, Cuvelier, & Berset, 1995). An aliquot (0.1 mL) of each extract, used for total polyphenol assay, was added to 3.9 mL of freshly prepared methanolic solution containing 0.24 g L − 1 DPPH, and held in the dark for 30 min at room temperature. Then, the absorbance was measured at 515 nm in 1 cm cuvettes, using a Shimadzu 1601 UV–Visible spectrophotometer (Tokyo, Japan). The working solution was prepared by dilution of methanolic DPPH to absorbance at ≃1.1 AU to gain the sufficient reaction capacity for higher contents of antioxidant in extracts. The percentage inhibition of DPPH was obtained by the following equation: [(AC(0) − AS(t))/AC(0)] × 100, where AC(0) is the absorbance of the blank control at the beginning of the assay, and AS(t) the sample absorbance after 30 min. 2.9. Statistical analysis All data were subjected to Bartlett's test for homogeneity of variance, before being subjected to analysis of variance. Means were separated by the Tukey's HSD or Student–Newmann–Keuls tests, when the F-test was significant. 3. Results
2.7. Quali-quantitative characterisation of phenolics by HPLC analysis
3.1. Head characteristics of the cultivars
2.7.1. Extraction procedure The extraction procedure, performed for six cultivars (i.e. ‘Camard’, ‘Camerys’, ‘Empolese’, ‘Locale di Mola’, ‘Opal’ and ‘Spinoso di Palermo’), was carried out as previously described by Pandino et al. (2010).
The main characteristics of head showed a high variability amongst cultivars with respect to size, shape (length/diameter, L/D, ratio) and colour of inner and outer bracts (Table 1). The average fresh weight of head varied from 117 g (‘Violetto di Sicilia clone 4/8’) to 225 g (‘Harmony F1’). Head shape was sub-spherical (L/D ratio 0.89) in ‘Camard’, spherical (about 1.02) in ‘Camerys’, ‘Nobre’, ‘Romanesco clone C3’ and ‘Tondo di Paestum’, cylindrical (1.42–1.50) in ‘Violetto di Sicilia clone 4/8’, ‘Violetto di Provenza’ and ‘Locale di Mola’, and conical (1.48) in ‘Spinoso di Palermo’. The colour of the outer bracts varied from deep green (e.g. ‘Blanc Hyérois’,) to deep purple (‘Tema 2000’ and ‘Concerto’) with a wide range of different colour hues. The colour of the inner bracts was yellow (e.g. ‘Nobre’), yellow with greenish (‘Blanc Hyérois’ and ‘Violetto di Sicilia clone 4/8’) or purple shades (e.g. ‘Tema 2000’).
2.7.2. HPLC analysis Each extract (20 μL) was analysed using a series 1200 HPLC instrument (Agilent Technologies, Palo Alto, CA) equipped with ChemStation software (B.03.01). Separations were achieved on a Zorbax Eclipse XDB-C18 (4.6× 150 mm; 5.0 μm particle size), operated at 30 °C, with a 0.2 μm stainless steel in-line filter. The method was adapted from Pandino et al. (2010): the mobile phase was 1% formic acid in water (solvent A) and in acetonitrile (solvent B) at a flow rate of 0.5 mL/min. The gradient started with 5% B to reach 10% B at 10 min, 40% B at 30 min, 90% B at 50 min, and 90% B at 58 min. Chromatograms were recorded at 280, 310, and 350 nm from diode array data collected between 200 and 600 nm. 2.7.3. Polyphenols' identification and quantification In this paper, 17 compounds, belonging to caffeoylquinic acids and flavones' groups, were separated using HPLC and identified by their retention times, comparison with commercially available standards, their UV/Vis spectra and available data in the literature (Lombardo et al., 2010; Pandino et al., 2011a,b). The LOD (limit of detection) and LOQ (limit of quantification) were reported in a previous study (Pandino et al., 2010). Amounts of mono- and di-caffeoylquinic acids were calculated at 310 nm using 5-caffeoylquinic acid and cynarin as references, respectively. In this paper, the caffeoylquinic acids are presented according to the recommended IUPAC numbering system
3.2. Total polyphenol content The total polyphenol content of the whole head, expressed either on a FM or a DM basis, was significantly cultivar-dependent (Table 2). ‘Tema 2000’ had the highest total polyphenol content of the whole head (7.4 g CAE kg− 1 FM, 58.7 g CAE kg− 1 DM), but ‘Nobre’ (6.7 g CAE kg− 1 FM, 40.1 g CAE kg− 1 DM) and ‘Violetto di Sicilia clone 4/8’ (6.4 g CAE kg− 1 FM, 47.0 g CAE kg− 1 DM) also represented a rich source of these compounds (Table 2). The lowest values were found in ‘Tempo’ (1.6 g CAE kg − 1 FM, 11.9 g CAE kg − 1 DM) and ‘Camerys’ (1.7 g CAE kg− 1 FM, 13.9 g CAE kg− 1 DM). The deviation was 393% on a FM basis and 403% on a DM basis. A significant (P ≤ 0.05) “cultivar× plant part” interaction (Table 3) was found. For example, ‘Tema 2000’ showed the highest total polyphenol content in the outer bracts and receptacle, whereas ‘Nobre’ and ‘Violetto di Sicilia clone 4/8’ obtained the highest
S. Lombardo et al. / Food Research International 46 (2012) 544–551 Table 2 Total polyphenol content (TPC) and dry matter (DM) contents of the whole globe artichoke head in relation to cultivar. Different letters within each column indicate statistically significant differences between means (P ≤ 0.05). Cultivar
TPC (g CAE kg− 1 FM)a TPC (g CAE kg− 1 DM) DM (%)
Blanc Hyérois Camard Camerys Concerto Empolese Harmony F1 Locale di Mola Madrigal F1 Nobre Opal Romanesco clone C3 Spinoso di Palermo Tema 2000 Tempo Tondo di Paestum Violetto di Provenza Violetto di Sicilia clone 4/8 Mean CV (%)
5.0 4.5 1.7 3.7 5.6 4.7 5.2 3.7 6.7 4.5 4.7 3.8 7.4 1.6 4.4 5.6 6.4 4.6 33
de (7) f (11) h (15) g (14) c (5) ef (8) cd (6) g (14) b (2) f (10) ef (9) g (13) a (1) h (16) f (12) c (4) b (3)
40.3 26.6 13.9 28.0 41.2 34.6 48.6 31.4 40.1 34.4 40.9 32.5 58.7 11.9 30.8 41.5 47.0 35.4 33
c (7) f (15) g (16) ef (14) c (5) d (9) b (2) de (12) c (8) d (10) c (6) e (11) a (1) h (17) de (13) c (4) b (3)
12.4 eg 16.9 a 12.2 eg 13.2 ce 13.6 bc 13.6 bc 10.7 h 11.8 fg 16.7 a 13.1 ce 11.5 gh 11.7 fh 12.6 df 13.4 bd 14.3 b 13.5 bd 13.6 bc 13.2 12
CAE: chlorogenic acid equivalent; FM: fresh matter; DM: dry matter; values in brackets represent the ranking order; and CV: coefficient of variation. a The data reported on a FM basis are calculated considering the incidence of each head parts (i.e. receptacle, inner and outer bracts) on the whole head weight.
values for the inner bracts and floral stem, respectively. ‘Camerys’ and ‘Tempo’ showed low levels of total polyphenol content in all plant parts (Table 3). Regardless of the cultivar (Table 3), the floral stem exhibited the highest total polyphenol content, whereas the outer bracts had the lowest amounts. The receptacle was fairly rich in total polyphenols (6.6 g CAE kg− 1 FM), whilst the inner bracts had an intermediate content (5.2 g CAE kg− 1 FM) (Table 3). Finally, the total polyphenol content of the whole head was significantly affected by harvest time, resulting higher in spring than in winter (6.0 vs. 5.2 g CAE kg− 1 FM). In particular, passing from winter to spring harvest the level of total polyphenols increased by 17 and 12%, respectively, in ‘Tema 2000’ and ‘Romanesco clone C3’ (data not shown).
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3.3. Quali-quantitative characterisation of polyphenol profile Concerning the quantitative and qualitative profiles of the individual polyphenols (flavones and caffeoylquinic acids), significant differences amongst cultivars and plant parts were found (Tables 4–7). From a quantitative point of view, total apigenin derivatives were the major polyphenol compounds in the receptacle, inner and outer bracts (2504 mg kg − 1 DM, on average of cultivars and plant parts), whereas in the floral stem caffeoylquinic acids were the most abundant (3436 mg kg − 1 DM, on average of cultivars) (Tables 4–7). Amongst the caffeoylquinic acids, 5-O-caffeoylquinic acid and 1,5-diO-caffeoylquinic acid were the main compounds and present mainly in the receptacle and floral stem. The remaining caffeoylquinic acids (i.e. 1- and 3-O-caffeoylquinic acids, 3,4-, 3,5- and 4,5-di-O-caffeoylquinic acids) were minor compounds in all parts of the plant analysed in this study (Tables 4–7). In particular, 3-O-caffeoylquinic acid, 3,4- and 3,5-di-O-caffeoylquinic acids were only present in ‘Locale di Mola’ and ‘Opal’ floral stems (Table 7). Apart from ‘Locale di Mola’ outer bracts, apigenin 7-O-glucuronide was the predominant flavones in the receptacle, inner and outer bracts, ranging from 177 (floral stem of ‘Empolese’) to 3901 mg kg− 1 DM (inner of ‘Camerys’) (Tables 4–7). ‘Camerys’ revealed the highest content of this compound in all plant parts analysed, but high amounts were also found in the receptacles of ‘Opal’ and ‘Empolese’ (2424 mg kg − 1 DM, on average; Table 6) and in the inner bracts of ‘Spinoso di Palermo’ and ‘Locale di Mola’ (2144 mg kg − 1 DM, on average; Table 5). In addition, ‘Opal’ receptacle, together with that of ‘Camard’, was also the richest in apigenin 7-O-glucoside and apigenin aglycone (591 and 160 mg kg− 1 DM, respectively; Table 6). Apigenin malonylglucoside was detected in all head parts and only in trace amounts in the floral stem (Tables 4–7). Except for ‘Locale di Mola’, total luteolin derivatives were abundant in the receptacle (375 mg kg− 1 DM, on average of cultivars) (Tables 4–7). In particular, the receptacles of ‘Camerys’ (567 mg kg− 1 DM) and ‘Spinoso di Palermo’ (506 mg kg− 1 DM) are worth being mentioned for their high contents of luteolin 7-O-glucoside and -glucuronide, respectively. As shown in Tables 4–7, luteolin and luteolin 7-O-rutinoside were minor compounds in all plant parts studied, whilst luteolin malonylglucoside was detected only in the floral stem (47 mg kg− 1 DM, on average of cultivars) (Table 7).
Table 3 Total polyphenol (TPC) and dry matter (DM) contents of plant parts in relation to cultivar. Different letters within each column indicate statistically significant differences between means (P ≤ 0.05). Cultivar
Blanc Hyérois Camard Camerys Concerto Empolese Harmony F1 Locale di Mola Madrigal F1 Nobre Opal Romanesco clone C3 Spinoso di Palermo Tema 2000 Tempo Tondo di Paestum Violetto di Provenza Violetto di Sicilia clone 4/8 Mean CV (%)
Outer bracts
Inner bracts
Receptacle
Floral stem
TPC (g CAE kg− 1 FM)
DM (%)
TPC (g CAE kg− 1 FM)
DM (%)
TPC (g CAE kg− 1 FM)
DM (%)
TPC (g CAE kg− 1 FM)
DM (%)
2.7 fi (12) 3.4 cf (7) 2.0 ij (15) 2.3 gi (13) 3.1 df (8) 2.7 fi (12) 3.7 cd (5) 3.6 ce (6) 4.0 bc (4) 2.8 fh (11) 2.9 eg (9) 2.1 hi (14) 5.3 a (1) 1.4 j (16) 2.9 fh (10) 4.0 bc (3) 4.6 b (2) 3.1 30
12.7 18.6 12.8 14.8 14.0 15.1 12.4 14.1 18.6 14.5 13.9 10.8 15.8 15.6 15.1 15.2 13.7 14.6 14
6.3 cd (7) 4.6 ef (10) 1.6 g (15) 3.8 f (13) 6.8 bc (5) 5.1 de (8) 6.4 c (6) 3.4 f (14) 8.1 a (1) 4.0 ef (12) 5.1 de (9) 4.4 ef (11) 7.8 ab (3) 1.3 g (16) 5.1 de (8) 7.4 ac (4) 7.9 ab (2) 5.2 38
12.8 ad 14.9 a 11.4 bd 11.6 ad 11.6 ad 12.5 ad 9.4 d 11.2 bd 14.2 ab 12.4 ad 10.4 cd 11.5 ad 10.6 cd 11.6 ad 12.9 ac 13. 0 ac 11.2 bd 12.0 11
7.2 ce (7) 5.0 hi (14) 3.9 j (16) 6.2 eg (11) 7.9 bc (5) 7.6 bd (6) 6.5 df (9) 4.6 ij (15) 8.5 b (3) 8.6 b (2) 8.0 bc (4) 5.7 fh (12) 11.3 a (1) 2.4 k (17) 6.3 eg (10) 5.4 gi (13) 7.1 de (8) 6.6 31
11.4 cd 15.2 a 11.9 bd 13.0 ad 14.8 ab 12.4 ad 12.7 ad 11.3 cd 13. 8 ad 11.4 cd 11.0 d 12.6 ad 12. 6 ad 11.4 cd 14.7 ab 13.6 ad 14.2 ac 12.8 10
5.1 f (11) 3.8 gh (13) 1.2 i (17) 2.8 h (15) 9.8 d (5) 7.8 d (7) 10.3 c (4) 8.1 d (6) 16.3 b (2) 7.3 de (8) 6.6 e (9) 3.6 gh (14) 16.0 b (3) 1.4 i (16) 4.2 fg (12) 5.1 f (10) 17.6 a (1) 7.5 66
11.0 ac 10.9 ac 8.6 c 10.6 ac 11.4 ac 10.2 bc 11.0 ac 11.5 ac 14.2 a 11.0 ac 8.4 c 9.5 c 10.6 ac 9.8 c 8.8 c 11.6 ac 13.4 ab 10.7 14
df a df bc be bc ef be a bd be f b bc bc bc ce
CAE: chlorogenic acid equivalent; FM: fresh matter; Values in brackets represent the ranking order; and CV: coefficient of variation.
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Table 4 Polyphenol (mg kg− 1 DM) content of outer bracts in relation to cultivar. Different letters amongst cultivars for each compound indicate statistically significant differences between means (P ≤ 0.05). Compound
1-O-caffeoylquinic acid 3-O-caffeoylquinic acid 5-O-caffeoylquinic acid 3,4-di-O-caffeoylquinic acid 3,5-di-O-caffeoylquinic acid 1,5-di-O-caffeoylquinic 4,5-di-O-caffeoylquinic Total caffeoylquinic acid Luteolin 7-O-rutinoside Luteolin 7-O-glucoside Luteolin 7-O-glucuronide Luteolin malonylglucoside Luteolin Total luteolin Apigenin 7-O-rutinoside Apigenin 7-O-glucoside Apigenin 7-O-glucuronide Apigenin malonylglucoside Apigenin Total apigenin
Cultivar Camard
Camerys
Empolese
Locale di Mola
Opal
Spinoso di Palermo
nd nd nd nd nd nd 24 ± 2 a 24 c nd nd nd nd nd 350 ± 19 bc nd 1440 ± 171 c 141 ± 12 ab 119 ± 13 a 2050 c
trace nd nd nd nd nd 35 ± 2 a 35 c 65 ± 4 a 54 ± 4 a 63 ± 3 b nd 90 ± 4 b 272 b 499 ± 14 b nd 2205 ± 231 a 165 ± 10 a 123 ± 11 a 2992 b
nd nd nd nd nd nd nd nd 20 ± 2 c 15 ± 1 c nd nd 35 e 218 ± 12 c nd 1257 ± 22 cd 77 ± 4 c 46 ± 2 c 1598 d
trace nd 282 ± 11 a nd nd nd trace 282 a 51 ± 1 b 34 ± 1 b 96 ± 2 a nd 171 ± 6 a 352 a 2665 ± 146 a nd 1060 ± 51 d trace 92 ± 7 b 3817 a
nd nd 59 ± 5 b nd nd 137 ± 6 nd 196 b nd 14 ± 1 d 16 ± 2 c nd 27 ± 4 c 57 d nd nd 975 ± 101 d 110 ± 14 b 90 ± 12 b 1175 e
nd nd 35 ± 5 c nd nd nd nd 35 c 26 ± 1 c 18 ± 1 cd 67 ± 1 b nd 17 ± 1 d 128 c nd nd 1812 ± 35 b 133 ± 14 ab 43 ± 2 c 1988 cd
DM: dry matter; 1-O-caffeoylquinic acid (Rt = 9.23 min); 3-O-caffeoylquinic acid (Rt = 10.8 min); 5-O-caffeoylquinic acid (or chlorogenic acid) (Rt = 15.9 min); 4-O-caffeoylquinic acid (Rt = 17.8 min); Luteolin 7-O-rutinoside (Rt = 25.2 min); 3,4-di-O-caffeoylquinic acid (Rt = 25.4 min); Luteolin 7-O-glucoside (Rt = 26.0 min); Luteolin 7-O-glucuronide (Rt = 26.3 min); 3,5-di-O-caffeoylquinic acid (Rt = 27.1 min); 1,5-di-O-caffeoylquinic acid (Rt = 27.6 min); Apingenin 7-O-rutinoside (Rt = 27.8 min); Apigenin 7-O-glucoside (Rt = 28.7 min); Apigenin 7-O-glucuronide (Rt = 29.2 min); Luteolin malonylglucoside (Rt = 29.7 min); 4,5-di-O-caffeoylquinic acid (Rt = 31.7 min); Apigenin malonylglucoside (Rt = 32.1 min); Luteolin (Rt = 35.0 min); Apigenin (Rt = 39.2 min); and Hesperetin (Rt = 40.1 min). Rt, indicated in brackets, means retention time value; nd: not detected.
3.4. Antioxidant activity
4. Discussion and conclusions
Antioxidant activity, expressed as percentage inhibition of DPPH radical, varied amongst cultivars and plant parts. With regard to the whole head, ‘Violetto di Sicilia clone 4/8’ had the highest antioxidant activity, whereas ‘Tempo’ revealed the lowest value (Fig. 1). A strongly significant (P ≤ 0.001) positive correlation (r = 0.37) was detected between the antioxidant activity and total polyphenol content both amongst cultivars and plant parts. Antioxidant activity in the floral stem was significantly higher than in the inner bracts, receptacle and outer bracts (Fig. 2).
In the present work, we reported the variation of polyphenol content and antioxidant activity of a large germplasm collection (17 cultivars) of globe artichoke in relation to the different plant parts (floral stem, receptacle, inner and outer bracts). In addition, we also investigated the effects of harvest time (winter and spring) on total polyphenol content. Firstly, a significant influence of cultivar was found on the content of both total polyphenols and individual polyphenols as previously demonstrated in other crops, including potato (Al-Weshahy & Rao, 2009), faba bean (Chaieb, González, López-Mesas, Bouslama, & Valiente, 2011) and tomato
Table 5 Polyphenol (mg kg− 1 DM) content of inner bracts in relation to cultivar. Different letters amongst cultivars for each compound indicate statistically significant differences between means (P ≤ 0.05). Compound
1-O-caffeoylquinic acid a 3-O-caffeoylquinic acid 5-O-caffeoylquinic acid 3,4-di-O-caffeoylquinic acid 3,5-di-O-caffeoylquinic acid 1,5-di-O-caffeoylquinic 4,5-di-O-caffeoylquinic Total caffeoylquinic acid Luteolin 7-O-rutinoside Luteolin 7-O-glucoside Luteolin 7-O-glucuronide Luteolin malonylglucoside Luteolin Total luteolin Apigenin 7-O-rutinoside Apigenin 7-O-glucoside Apigenin 7-O-glucuronide Apigenin malonylglucoside Apigenin Total apigenin
Cultivar Camard
Camerys
Empolese
Locale di Mola
Opal
Spinoso di Palermo
nd nd nd nd nd 189 ± 23 d 26 ± 2 b 215 e nd nd 12 ± 1 d nd 15 ± 2 c 27 e nd 81 ± 8 b 1847 ± 211 c 183 ± 21 b 294 ± 34 a 2405 b
trace nd 105 ± 10 d nd nd 276 ± 24 d 31 ± 1 b 412 d 31 ± 1 b 19 ± 1 79 ± 6 b nd 24 ± 2 bc 153 c nd 111 ± 11 ab 3901 ± 238 a 187 ± 10 b 235 ± 13 bc 4434 a
nd nd nd nd nd nd nd – nd nd nd nd nd – 199 ± 10 nd 1873 ± 102 bc 61 ± 3 d 133 ± 7 d 2266 b
30 ± 1 b nd 686 ± 29 b nd nd 925 ± 37 b 49 ± 2 a 1690 b 46 ± 3 a nd 75 ± 4 b nd 102 ± 7 a 223 b nd 130 ± 10 a 2027 ± 106 bc 106 ± 5 c 217 ± 13 c 2480 b
trace nd 233 ± 13 c nd nd 595 ± 39 c 43 ± 3 a 871 c nd nd 31 ± 2 c nd 33 ± 1 b 64 d nd nd 1753 ± 134 c 174 ± 13 b 265 ± 20 ab 2192 b
81 ± 0.3 a nd 1246 ± 23 a nd nd 2071 ± 38 a trace 3398 a 36 ± 1 b nd 191 ± 2 a nd 32 ± 1 b 259 a nd nd 2261 ± 27 b 254 ± 17 a 64 ± 2 e 2579 b
DM: dry matter and nd: not detected. a See note in Table 6 for the retention time values of the identified compounds.
S. Lombardo et al. / Food Research International 46 (2012) 544–551
549
Table 6 Polyphenol (mg kg− 1 DM) content of receptacle in relation to cultivar. Different letters amongst cultivars for each compound indicate statistically significant differences between means (P ≤ 0.05). Compound
Cultivar
a
1-O-caffeoylquinic acid 3-O-caffeoylquinic acid 5-O-caffeoylquinic acid 3,4-di-O-caffeoylquinic acid 3,5-di-O-caffeoylquinic acid 1,5-di-O-caffeoylquinic 4,5-di-O-caffeoylquinic Total caffeoylquinic acid Luteolin 7-O-rutinoside Luteolin 7-O-glucoside Luteolin 7-O-glucuronide Luteolin malonylglucoside Luteolin Total luteolin Apigenin 7-O-rutinoside Apigenin 7-O-glucoside Apigenin 7-O-glucuronide Apigenin malonylglucoside Apigenin Total apigenin
Camard
Camerys
Empolese
Locale di Mola
Opal
Spinoso di Palermo
trace nd 116 ± 4 d nd nd 530 ± 28 d nd 646 d 24 ± 1 50 ± 2 b 112 ± 5 c nd 88 ± 4 a 274 d nd 422 ± 29 b 1920 ± 98 bc 364 ± 16 a 168 ± 8 a 2874 bc
trace nd 91 ± 5 d nd nd 500 ± 10 d 30 ± 1 621 d nd 567 ± 37 a nd nd 48 ± 3 c 615 a nd 288 ± 28 c 2686 ± 222 a 98 ± 4 c 78 ± 5 b 3150 ab
nd nd 165 ± 18 d nd nd 393 ± 54 d nd 558 d nd nd 60 ± 7 d nd 4 ± 0.4 d 64 c nd 121 ± 12 d 2215 ± 241 b 105 ± 10 c 33 ± 4 c 2474 c
trace nd 560 ± 39 c nd nd 761 ± 53 c trace 1321 c nd nd nd nd nd – nd 93 ± 6 d 902 ± 68 d 103 ± 6 c 12 ± 1 d 1110 e
61 ± 7 b trace 758 ± 97 b nd nd 1818 ± 99 b nd 2637 b nd 85 ± 4 b 272 ± 13 b nd 60 ± 4 b 417 c nd 591 ± 34 a 2633 ± 125 a 217 ± 8 b 160 ± 9 a 3601 a
108 ± 1 a nd 976 ± 10 a nd nd 2375 ± 33 a nd 3459 a nd nd 506 ± 13 a nd trace 506 b nd 324 ± 8 c 1559 ± 45 c trace trace 1883 d
DM: dry matter and nd: not detected. a See note in Table 6 for the retention time values of the identified compounds.
(Vallerdú-Queralt et al., 2011). From a quantitative point of view, we highlighted that the total polyphenol content of the whole globe artichoke head ranged from 1.2% to 5.9%, as measured on a DM basis. Cultivars with a total polyphenol content within the upper part of this range (‘Tema 2000’, ‘Nobre’ and ‘Violetto di Sicilia clone 4/8’) are probably best suited for the fresh consumption. Amongst them, ‘Violetto di Sicilia clone 4/8’ had also the major antioxidant activity and, hence, it may be also a potential target for the industrial recovery of natural antioxidants aimed to replace the synthetic ones. On the other hand, high levels of polyphenols can be undesirable, since they are associated with either enzymatically and nonenzymatically oxidative browning reactions (Lattanzio, Cardinali, Di Venere, Linsalata, & Palmieri, 1994; Peschel et al., 2006). Therefore, ‘Tempo’, characterised by a low content of total polyphenols, resulted more suitable for food processing in virtue of its presumable less
proneness to brown during handling and storage (Lattanzio, 2003). In addition, the data about the polyphenol profile of six cultivars (i.e. ‘Camard’, ‘Camerys’, ‘Empolese’, ‘Locale di Mola’, ‘Opal’ and ‘Spinoso di Palermo’), not previously analysed, combined with those of our previous studies (Lombardo et al., 2010; Pandino et al., 2011b), may allow to select cultivars for more specific pharmaceutical applications (extraction of specific polyphenols). Regardless of cultivar, as already observed (Fratianni, Tucci, De Palma, Pepe, & Nazzaro, 2007; Lombardo, Pandino, Mauro, & Mauromicale, 2009; Lombardo et al., 2010; Pandino et al., 2011a,b), individual polyphenols were preferentially accumulated in specific parts of the plant, presumably related to their role (Pandino et al., 2011a,b). In particular, the floral stem was the best source of caffeoylquinic acids, mainly chlorogenic acid (5-O-caffeoylquinic acid) and 1,5-di-O-caffeoylquinic acid. Thus, this
Table 7 Polyphenol (mg kg− 1 DM) content of floral stem in relation to cultivar. Different letters amongst cultivars for each compound indicate statistically significant differences between means (P ≤ 0.05). Compound
1-O-caffeoylquinic acid a 3-O-caffeoylquinic acid 5-O-caffeoylquinic acid 3,4-di-O-caffeoylquinic acid 3,5-di-O-caffeoylquinic acid 1,5-di-O-caffeoylquinic 4,5-di-O-caffeoylquinic Total caffeoylquinic acid Luteolin 7-O-rutinoside Luteolin 7-O-glucoside Luteolin 7-O-glucuronide Luteolin malonylglucoside Luteolin Total luteolin Apigenin 7-O-rutinoside Apigenin 7-O-glucoside Apigenin 7-O-glucuronide Apigenin malonylglucoside Apigenin Total apigenin
Cultivar Camard
Camerys
Empolese
Locale di Mola
Opal
Spinoso di Palermo
nd nd 337 ± 24 d nd nd 854 ± 64 d trace 1191 e 38 ± 2 b 24 ± 1 b nd 33 ± 2 c 18 ± 1 113 b nd trace nd trace trace –
46 ± 6 b nd 356 ± 11 d nd nd 719 ± 23 d trace 1121 e 50 ± 3 a 37 ± 2 b nd 51 ± 7 b nd 138 a nd nd nd nd nd –
nd trace 932 ± 28 c nd nd 1223 ± 50 d nd 2155 d 34 ± 1 b 26 ± 1 b nd nd nd 60 c nd nd 177 ± 15 trace nd 177
trace 44 ± 2 1787 ± 176 b 131 ± 5 a 178 ± 14 a 3364 ± 206 b 52 ± 4 5556 b nd 28 ± 3 b nd 31 ± 3 c nd 59 c nd nd nd nd nd –
53 ± 2 b trace 1045 ± 14 c 44 ± 5 b 42 ± 3 b 2193 ± 270 c trace 3377 c nd 67 ± 8 a nd 72 ± 7 a nd 139 a nd nd nd trace nd –
83 ± 4 a nd 2877 ± 148 a nd nd 4255 ± 215 a nd 7215 a 46 ± 2 a nd nd nd nd 46 c nd nd nd nd nd –
DM: dry matter and nd: not detected. a See note in Table 6 for the retention time values of the identified compounds.
550
S. Lombardo et al. / Food Research International 46 (2012) 544–551
Fig. 1. Antioxidant activity (AA) of the whole globe artichoke head in relation to cultivar. Different letters indicate statistically significant differences between means (P ≤ 0.05).
plant part, generally discarded as waste matter, may represent an unexploited source of natural antioxidants hitherto (Larossa, Llorach, Espin, & Tomas-Barberan, 2002), whose industrial recovery could represent an added economic value for the producers and processors (Peschel et al., 2006). According to our data, the use of ‘Spinoso di Palermo’ and ‘Locale di Mola’ floral stems (rich in caffeoylquinic acids), together with those of ‘Nobre’ and ‘Violetto di Sicilia’ (Lombardo et al., 2009; Lombardo et al., 2010; Pandino et al., 2011a), is suggested for the extraction of natural antioxidants. The receptacle, considered as the main edible part of the plant, showed an intermediate level of total polyphenols between the floral stem and bracts. Besides having a good content of total caffeoylquinic acids, this head part was also rich in total apigenin (mainly apigenin 7-O-glucuronide) and luteolin. This result is important since flavones such as apigenin exhibit potent biological effects in vitro and in vivo (Aljancic et al., 1999; Birt, Mitchell, Gold, Pour, & Pinch, 1997; Rossoni, Grande, Galli, & Visioli, 2005; Van Acker et al., 1996). In this respect, the receptacles of ‘Camerys’ and ‘Opal’ proved to be an interesting source of apigenin derivatives, mainly apigenin 7-O-glucuronide, after ‘Romanesco C3’ and ‘Concerto’ (Lombardo et al., 2010). Furthermore, the inner bracts,
the richest in total apigenin (2726 mg kg− 1 DM, on average of cultivars) amongst plant parts analysed, might be revaluated since, if properly prepared, are also edible. Thus, the presence of high amount of polyphenols in the edible part of globe artichoke plant, combined with the enhanced interest for ‘functional’ foods by consumers, may encourage the globe artichoke consumption on a wider scale. As highlighted by the results acquired, although the level of polyphenols is strictly under genetic control (Moglia et al., 2008), it could be subjected to marked and significant variations also in relation to harvest time. In particular, the weather conditions recorded in spring time (data not shown), represented mainly by the highest average maximum temperatures, are presumably more favourable to polyphenol bio-synthesis in both cultivars studied (i.e. ‘Romanesco clone C3’ and ‘Tema 2000’). This trend, for ‘Romanesco clone C3’, was also found for the individual polyphenols (Lombardo et al., 2010). In conclusion, probably the most important outcomes of this study were the comparison of a large number of globe artichoke cultivars for the total polyphenol content and the evaluation of the polyphenol profile of six cultivars not previously analysed. Our results, including
90
a
AA (%)
89
88
b
b
b
87
86
85
outer bracts
inner bracts
receptacle
floral stem
Fig. 2. Antioxidant activity (AA) of globe artichoke in relation to the plant part (values are the mean of measurements on cultivars). Different letters indicate statistically significant differences between means (P ≤ 0.05).
S. Lombardo et al. / Food Research International 46 (2012) 544–551
those of our previous works (Lombardo et al., 2010; Pandino et al., 2011a), demonstrated the high level of biodiversity in the globe artichoke germplasm for the amount of polyphenols. This important nutritional and technological characteristic may preserve cultivars from genetic erosion through their selection for a specific end-use (fresh market, food processing, pharmaceutical applications, etc.). On the other side, we also suggest that, considering the value – both nutritional and pharmaceutical – of polyphenols, it should be the case to initiate a breeding programme in order to improve the total polyphenol content of the globe artichoke head, mainly for cultivars destined for fresh consumption. An interesting aspect for future research will be to ascertain the variation of polyphenol content in response to the other factors (i.e. cultivation environment, crop management practices, etc.) that may affect polyphenol biosynthesis and accumulation in globe artichoke plants, as well as to clarify the interaction between gene expression and the biosynthesis of polyphenols. Acknowledgement This research was partially supported by the CAR-VARVI project (MiPAF). The authors are grateful to Mr. Antonino Russo for his agronomical assistance. References Alamanni, M. C., & Cossu, M. (2003). Antioxidant activity of the extracts of the edible part of artichoke (Cynara scolymus L.) var. Spinoso sardo. Italian Journal of Food Science, 15, 187–195. Aljancic, I., Vajs, V., Menkovic, N., Karadzic, I., Juranic, N., Milosavljevic, S., et al. (1999). Flavones and sesquiterpene lactones from Achillea atrata subsp. multifida: Antimicrobial activity. Journal of Natural Products, 62, 909–911. Al-Weshahy, A., & Rao, A. V. (2009). Isolation and characterization of functional components from peel samples of six potatoes varieties growing in Ontario. Food Research International, 42, 1062–1066. Beckman, C. H. (2000). Phenolic-storing cells: Keys to programmed cell death and periderm formation in wilt disease resistance and in general defence responses in plants? Physiological and Molecular Plant Pathology, 57, 101–110. Birt, D. F., Mitchell, D., Gold, B., Pour, P., & Pinch, H. C. (1997). Inhibition of ultraviolet light-induced skin carcinogenesis in SKH-1 mice by apigenin, a plant flavonoid. Anticancer Research, 17, 85–91. Brand-Williams, W., Cuvelier, M. E., & Berset, C. (1995). Use of a free radical method to evaluate antioxidant activity. Lebensmittel-Wissenschaft und —Technologie, 22, 25–30. Brat, P., Georgé, S., Bellamy, A., Du Chaffaut, L., Scalbert, A., Mennen, L., et al. (2006). Daily polyphenol intake in France from fruit and vegetables. Journal of Nutrition, 136, 2368–2373. Bravo, L. (1998). Polyphenols: Chemistry, dietary sources, metabolism, and nutritional significance. Nutrition Reviews, 56, 317–333. Chaieb, N., González, J. L., López-Mesas, M., Bouslama, M., & Valiente, M. (2011). Polyphenols content and antioxidant capacity of thirteen faba bean (Vicia faba L.) genotypes cultivated in Tunisia. Food Research International, 44, 970–977. Curadi, M., Ceccarelli, N., Graifenberg, A., & Picciarelli, P. (2004). Composti ad attività antiossidante nei capolini di carciofo: differenze varietali. Italus Hortus, 11, 81–84. FAO (2009). http://www.faostat.fao.org. Fratianni, F., Tucci, M., De Palma, M., Pepe, R., & Nazzaro, F. (2007). Polyphenolic composition in different parts of some cultivars of globe artichoke (Cynara cardunculus L. var. scolymus (L.) Fiori). Food Chemistry, 104, 1282–1286. IUPAC (1976). Nomenclature of cyclitols. Biochemical Journal, 153, 23–31. Kähkönen, M. P., Hopia, A. I., Vuorela, H. J., Rauha, J. P., Pihlaja, K., & Kujala, T. S. (1999). Antioxidant activity of plant extracts containing phenolic compounds. Journal of Agricultural and Food Chemistry, 47, 3954–3962.
551
Larossa, M., Llorach, R., Espin, J. C., & Tomas-Barberan, F. A. (2002). Increase of antioxidant activity of tomato juice upon functionalisation with vegetable byproduct extracts. Lebensmittel-Wissenschaft und —Technologie, 35, 532–542. Lattanzio, V. (2003). Bioactive polyphenols: Their role in quality and storability of fruit and vegetables. Journal of Applied Botany, 77, 128–146. Lattanzio, V., Cardinali, A., Di Venere, D., Linsalata, V., & Palmieri, S. (1994). Browning phenomena in stored artichoke (Cynara scolymus L.) heads: Enzymatic or chemical reactions? Food Chemistry, 50, 1–7. Lattanzio, V., Kroon, P. A., Linsalata, V., & Cardinali, A. (2009). Globe artichoke: a functional food and source of nutraceutical ingredients. Journal of Functional Foods, 1, 131–144. Lombardo, S., Pandino, G., Mauro, R., & Mauromicale, G. (2009). Variation of phenolic content in globe artichoke in relation to biological, technical and environmental factors. Italian Journal of Agronomy, 4, 181–189. Lombardo, S., Pandino, G., Mauromicale, G., Knödler, M., Carle, R., & Schieber, A. (2010). Influence of genotype, harvest time and plant part on polyphenolic composition of globe artichoke [Cynara cardunculus L. var. scolymus (L.) Fiori]. Food Chemistry, 119, 1175–1181. Manach, C., Scalbert, A., Morand, C., Rémésy, C., & Jimènez, L. (2004). Polyphenols: Food sources and bioavailability. American Journal of Clinical Nutrition, 79, 727–747. Mauromicale, G., & Ierna, A. (2000). Characteristics of heads of seed-grown globe artichoke [Cynara cardunculus L. var. scolymus (L.) Fiori] as affected by harvest period, sowing date and gibberellic acid. Agronomie, 20, 197–204. Moglia, A., Lanteri, S., Comino, C., Acquadro, A., De Vos, R., & Beekwilder, J. (2008). Stress-induced biosynthesis of dicaffeoylquinic acids in globe artichoke. Journal of Agricultural and Food Chemistry, 56, 8641–8649. Pandino, G., Courts, F. L., Lombardo, S., Mauromicale, G., & Williamson, G. (2010). Caffeoylquinic acids and flavonoids in the immature inflorescence of globe artichoke, wild cardoon, and cultivated cardoon. Journal of Agricultural and Food Chemistry, 58, 1026–1031. Pandino, G., Lombardo, S., Mauromicale, G., & Williamson, G. (2011a). Phenolic acids and flavonoids in leaf and floral stem of cultivated and wild Cynara cardunculus L. genotypes. Food Chemistry, 126, 417–422. Pandino, G., Lombardo, S., Mauromicale, G., & Williamson, G. (2011b). Profile of polyphenols and phenolic acids in bracts and receptacles of globe artichoke (Cynara cardunculus var. scolymus) germplasm. Journal of Food Composition and Analysis, 24, 148–153. Peschel, W., Sànchez-Rabaneda, F., Diekmann, W., Plescher, A., Gartzìa, I., Jimènez, D., et al. (2006). An industrial approach in the search of natural antioxidants from vegetable and fruit wastes. Food Chemistry, 97, 137–150. Racchi, M., Daglia, M., Lanni, C., Papetti, A., Govoni, S., & Gazzani, G. (2002). Antiradical activity of water soluble components in common diet vegetables. Journal of Agricultural and Food Chemistry, 50, 1272–1277. Rossoni, G., Grande, S., Galli, C., & Visioli, F. (2005). Wild artichoke prevents the ageassociated loss of vasomotor function. Journal of Agricultural and Food Chemistry, 53, 10291–10296. Scalbert, A., & Williamson, G. (2000). Dietary intake and bioavailability of polyphenols. Journal of Nutrition, 130, 2073S–2085S. Schütz, K., Kammerer, D., Carle, R., & Schieber, A. (2004). Identification and quantification of caffeoylquinic acids and flavonoids from artichoke (Cynara scolymus L.) heads, juice, and pomace by HPLC-DAD-ESI/MSn. Journal of Agricultural and Food Chemistry, 52, 4090–4096. Shahidi, F., & Naczk, M. (1995). Food phenolics: Sources, chemistry, effects and applications. Lancaster: Technomic Publishing Company. Singleton, V. L., & Rossi, J. A. J. R. (1965). Colorimetry of total phenolics with phosphomolybdic phosphotungstic acid reagents. American Journal of Enology and Viticulture, 16, 144–158. Vallerdú-Queralt, A., Medina-Remón, A., Martínez-Huélamo, M., Jáuregui, O., AndresLacueva, C., & Lamuela-Raventos, R. M. (2011). Phenolic profile and hydrophilic antioxidant capacity as chemotaxonomic markers of tomato varieties. Journal of Agricultural and Food Chemistry, 59, 3994–4001. Van Acker, S. A. B. E., Van Den Berg, D., Tromp, M. N. J. L., Griffioen, D. E., Van Bennekom, W. P., Van Der Vijgh, W. J. F., et al. (1996). Structural aspects of antioxidant activity of flavonoids. Free Radical Biology & Medicine, 20, 331–342. Zdunczyk, Z., Frejnagela, S., Wróblewska, M., Juśkiewicz, J., Oszmiańskib, J., & Estrella, I. (2002). Biological activity of polyphenol extracts from different plant sources. Food Research International, 35, 183–186.