Compounds with Antioxidant Properties in Pistachio (Pistacia vera L.) Seeds

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107

Compounds with Antioxidant Properties in Pistachio (Pistacia vera L.) Seeds Marcello Saitta, Daniele Giuffrida, Giuseppa Di Bella, Giovanna Loredana La Torre, Giacomo Dugo Dipartimento di Scienze degli Alimenti e dell’Ambiente “G. Stagno d’Alcontres”, Universita` di Messina, Messina, Italy

CHAPTER OUTLINE Introduction 910 Botanical Description 910 Historical Cultivation and Usage 910 Present-Day Cultivation and Usage 910 Applications to Health Promotion and Disease Prevention 911

909 Antioxidants in pistachio seeds 911 Effects of the use of pistachio nuts on health 915

Adverse Effects and Reactions (Allergies and Toxicity) 917 Summary Points 917 References 918

Antioxidants: classification and activity evaluation 911

LIST OF ABBREVIATIONS AOP, antioxidant potential CoA , coenzime A DNA, deoxyribonucleic acid GSH, glutathione HDL, high density lipoprotein LDL, low density lipoprotein MDA, malondialdehyde RNS, reactive nitrogen species ROS, reactive oxygen species Nuts & Seeds in Health and Disease Prevention. DOI: 10.1016/B978-0-12-375688-6.10107-0 Copyright Ó 2011 Elsevier Inc. All rights reserved.

PART 2 Effects of Specific Nuts and Seeds

SOD, superoxide dismutase TAA, total antioxidant activity TBARS, thiobarbituric acid-reactive substances TEAC, Trolox equivalent antioxidative capacity

INTRODUCTION Oxidative stress plays a role in the pathology of cancer, arteriosclerosis, neurodegenerative diseases, and aging processes. Fruits and vegetables provide protection against several diseases, such protection being attributed to antioxidants. In living systems, dietary antioxidants and endogenous enzymes protect against oxidative damage. Phenols are able to reduce in vitro oxidation of LDL; scientific studies have proved that antioxidants protect cells from free radical damage. The use of antioxidants as chemopreventive agents by inhibiting radical generation has been suggested, since free radicals are responsible for DNA damage and scavengers are probably important in cancer prevention (Moure et al., 2001). We herein report on the antioxidants found in pistachio seeds and their benefits to human health.

BOTANICAL DESCRIPTION

910

Pistacia vera L. is a diploid member of the order Sapindales, family Anacardiaceae. This plant is a tree that grows up to 10 m tall, with a single or several trunks. Leaves are deciduous, compound-pinnate, 10e20 cm long, with three to five oval leaflets. Pistachio is dioecious, with staminate and pistillate inflorescences; both types of flowers are apetalous, and wind is the pollinating agent. Mature pistillate flowers consist of two to five tepals and a pistil with three stigmas. Although commercial pistachios are known as nuts, the pistachio fruit is actually a drupe with an exocarp, a mesocarp (hull), and a hard, dehiscent endocarp (shell) that splits longitudinally when the fruit has ripened. Commercial pistachios comprise the shell and the edible kernel, which has a papery seed coat (skin), the color of which ranges from yellow to green (Hormaza & Wunsch, 2007).

HISTORICAL CULTIVATION AND USAGE The pistachio probably originated in central and southwestern Asia. Local human populations used the wild trees as a source of fuel, and for heavy pasturing of cattle. The presence of pistachio nuts in archeological excavations provides evidence that the pistachio has long been associated with human activities. Pistachio cultivation is very ancient; in fact, remnants of pistachio nuts dating from 6 BC have been found in Afghanistan and Iran. From its presumed center of origin, pistachio cultivation was extended within the ancient Persian Empire, from where it gradually expanded westward. The name “pistachio” probably derives from the word pistak in the ancient Persian language, Avestan. Pistachio nuts are mentioned in the Bible as precious gifts carried from Canaan to Egypt by the sons of Jacob. Pistachio cultivation spread into Mediterranean countries between 1 BC and 1 AD, with the advent of the Roman empire (Hormaza & Wunsch, 2007).

PRESENT-DAY CULTIVATION AND USAGE Trees are planted in orchards, and take approximately 7e10 years to reach significant production. Production is alternate-bearing or biennial-bearing, meaning that the harvest is heavier in alternate years. Peak production is reached at approximately 20 years. Trees are usually pruned to a size to make harvesting easier. One male tree produces enough pollen for 8e12 nut-bearing females. The kernels are often consumed as a snack food and eaten whole, either fresh or roasted and salted, and are also used in the food industry as an ingredient in ice cream, pastries, fermented meats, puddings, and in confections such as baklava and cold cuts such as mortadella (Hormaza & Wunsch, 2007).

CHAPTER 107 Antioxidants in Pistachio Seeds

APPLICATIONS TO HEALTH PROMOTION AND DISEASE PREVENTION Antioxidants: classification and activity evaluation During lipid oxidation, antioxidants with various functions act in different ways, binding metal ions, scavenging and quenching radicals, and decomposing peroxides. Often many mechanisms are involved, and this can cause synergistic effects. Antioxidants either prevent reactive oxygen species (ROS) and reactive nitrogen species (RNS) from being formed, or remove them before they can damage vital components of the cell. ROS include singlet oxygen, superoxide anions, hydroxyl radicals, and hydrogen peroxide; RNS include nitric oxide and peroxynitrite. Antioxidant classification depends on whether they are soluble in water (hydrophilic) or in lipids (hydrophobic, lipophilic). Another classification considers primary (chain-breaking) and secondary (reducing the rate of chain initiation) antioxidants; some compounds possess both activities. Antioxidant efficiency is determined by several factors (intrinsic chemical reactivity toward the radicals, site of radical generation, fate of antioxidant derived radicals, concentration and mobility of the antioxidant, biological absorption, and interactions with other antioxidants). The chemical reactivity towards the radicals is very important, because the antioxidants must scavenge the radicals before they can attack the target molecule. The site of radical generation may be the aqueous phase or the lipophilic domain of membranes and lipoproteins; in the first case hydrophilic antioxidants can act more efficiently, while in the second the lipophilic ones are preferred. The antioxidant activity must be evaluated with different tests for different mechanisms. Frequently used methods for measuring the oxidative damage evaluate total oxidative DNA damage, levels of antioxidant enzymes, levels of low molecular weight antioxidants (catalase, superoxide dismutase, glutathione peroxidases, uric acid, glutathione, flavonoids, catechins, anthocyanins, vitamin C, b-carotene, and vitamin E), oxidative damage to lipids (isoprostanes, thiobarbituric acid-reactive substances (TBARS)), and protein damage (numbers of protein carbonyl and modified tyrosine residues). Most of the chemical methods are based on the ability to scavenge different free radicals, but UV absorption and chelation ability are also responsible for the antioxidant activity in oily systems. The redox potential, reducing power, and degradation rate of the antioxidant substance have also been positively correlated with antioxidant activity (Moure et al., 2001).

Antioxidants in pistachio seeds There has been limited research on the composition of pistachio seeds over the past 30 years; Table 107.1 summarizes the literature data regarding the antioxidants found. An anthocyanin, cyanidin-3-galactoside, was found in pistachio kernels by Miniati (1981). Cyanidin-3-galactoside and cyanidin-3-glucoside (Figure 107.1) were found by other authors in kernels and skins (Wu & Prior, 2005; Seeram et al., 2006; Bellomo & Fallico, 2007). In particular, Seeram et al. (2006) showed that these anthocyanins are exclusively present in the skins; the authors found values of 696 mg/kg for cyanidin-3-galactoside, 209 mg/kg for cyanidin-3-glucoside in raw nuts, and 462 and 87 mg/kg, respectively, in roasted nuts. Anthocyanin levels decreased when the nuts were subjected to bleaching using hydrogen peroxide. The antioxidant activity was evaluated with the TEAC method, and the results showed that the oxygen-radical absorbing capacity of the nuts was correlated to the anthocyanin concentration. Bellomo and Fallico (2007) found a correlation between cyanidin3-galactoside concentration in skins and ripeness: values were very low or under the detection limit in unripe pistachios, reached 107e145 mg/kg in intermediate samples, and finally were 287e426 mg/kg in ripe pistachios. Furthermore, Wu and Prior (2005) affirmed that pistachios are the only tree nut that contains anthocyanins. Yalpani and Tyman (1983) investigated the presence of phenolic acids in the outer green shell of the pistachio nut. They found about 1.5% of anacardic acids (6-alkylsalicylic acids with 13, 15, and 17 carbon atoms in the alkyl chains, saturated and monounsaturated) in dried shells

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TABLE 107.1 Antioxidant Compounds Found in Pistachio Seeds (Literature Data 1981e2009) Compounds

Seed Part

Cyanidin-3-galactoside Various anacardic acids (6-alkylsalicylic acids) Resveratrol (3,5,40 -trihydroxystilbene) Anthocyanins (cyanidin-3-galactoside, cyanidin-3-glucoside) Lutein, violaxanthin, neoxanthin, luteoxanthin, b-carotene, chlorophylls, pheophytins Lutein, b-carotene, b-tocopherol, g-tocopherol, d-tocopherol Rutin, eriodictyol, quercetin, luteolin, naringenin, apigenin, cianidyn3-galactoside, cyanidin-3-glucoside Cyanidin-3-galactoside, cyanidin-3glucoside, chlorophylls, lutein, b-carotene Vitamin C, a-tocopherol, g-tocopherol, trans-resveratrol, proanthocyanidins, daidzein, genistein Trans-resveratrol, trans-resveratrol3-O-b-glucoside Various cardanols (3-alkylphenols)

References

Kernel Hull

Miniati (1981) Yalpani & Tyman (1983)

Kernel Kernel

Tokusoglu et al. (2005) Wu & Prior (2005)

Kernel

Giuffrida et al. (2006)

Kernel

Kornsteiner et al. (2006)

Skin and kernel

Seeram et al. (2006)

Skin and kernel

Bellomo & Fallico (2007)

Kernel

Gentile et al. (2007)

Kernel

Grippi et al. (2008)

Kernel

Saitta et al. (2009)

912

OH

OH OH

HO

OH

O

HO

O

H

H

OH

O

H

H

OH

OH H

O H OH

HO

H

H

OH O

O

HO

HO

Cyanidin-3-galactoside

OH OH

H

H

Cyanidin-3-glucoside

OH R

OH HO OH

O

Anacardic acid (R=alkyl)

OH

trans-Resveratrol

FIGURE 107.1 Structures of antioxidants found in pistachio seeds: anthocyanins, anacardic acids, resveratrol.

CHAPTER 107 Antioxidants in Pistachio Seeds

(Figure 107.1). Goli et al. (2005) evaluated the total phenolic content of the pistachio hull in 32e34 mg/g (dry weight) of the samples, and suggested the use of the extracts as alternative natural antioxidants. The detection of the products of ROS was used in the hypoxanthine/ xanthine oxidase assay to evaluate the antioxidant properties of various anacardic acids (Trevisan et al., 2006); authors found that these compounds are more potent antioxidants than hydroxytyrosol or caffeic acid. Resveratrol, trans-3,5,40 -trihydroxystilbene (Figure 107.1), was found by some authors in pistachio kernels (Tokusoglu et al., 2005; Gentile et al., 2007; Grippi et al., 2008). This compound has been associated with a reduction in cardiovascular disease by inhibiting or altering platelet aggregation and coagulation, or modulating lipoprotein metabolism (Grippi et al., 2008). The resveratrol contents found by Tokusoglu et al. (2005) were higher (0.09e 1.67 mg/kg, mean value 1.15 mg/kg) than those reported by Gentile et al. (2007) and Grippi et al. (2008); both found a mean value of 0.12 mg/kg, but the presence of the glycosidic derivative trans-piceid (trans-resveratrol-3-O-b-glucoside) was reported in higher concentrations with respect to free resveratrol, with a mean value of 6.97 mg/kg (Grippi et al., 2008). Lutein, violaxanthin, neoxanthin, luteoxanthin, and b-carotene (Figure 107.2) were found in pistachio kernels by Giuffrida et al. (2006); other authors reported only the presence of lutein and b-carotene (Kornsteiner et al., 2006; Bellomo & Fallico, 2007). It is known that the potential health benefits of carotenoid-rich diets are due to their role (antioxidants and agents preventing cardiovascular diseases and degenerative eye pathologies) (Giuffrida et al., 2006). Carotenoids are correlated to pistachio ripeness, and the highest lutein concentrations were found in unripe samples, 41.3e52.1 mg/kg, while intermediate samples showed concentrations of 17.9e34.7 mg/kg, and ripe sample concentrations of 18.1e37.7 mg/kg (Bellomo & Fallico, 2007); the same authors found b-carotene contents below 1.8 mg/kg. Kornsteiner et al. (2006) found similar concentrations (lutein mean value 44 mg/kg, b-carotene mean value 4 mg/kg). Giuffrida et al. (2006) found higher concentrations of b-carotene (mean value 7.1 mg/kg) and intermediate levels of lutein (mean value 29.14 mg/kg); violaxanthin, neoxanthin, and luteoxanthin had mean values of 2.81, 3.04, and 2.75 mg/kg, respectively. Chlorophylls and chlorophyll-derived compounds were identified in Sicilian pistachio kernels by Giuffrida et al. (2006). In this work, chlorophyll a, chlorophyll b, and pheophytin a were reported to be present at 54.14, 30.2, and 25.68 mg/kg, respectively. Different contents of chlorophyll a and b in pistachio kernels from various countries were reported by Bellomo and Fallico (2007); the chlorophyll a content range was 18.3e150.6 mg/kg and the chlorophyll b content range was 7.1e49.7 mg/kg . Chlorophylls and related molecules’ chemical structures present a conjugated tetrapyrrole ring which allows them to absorb light, and this is directly involved in the color and oxidative stability of the food products that contain these pigments (Giuffrida et al., 2006). Three tocopherols (b, g, and d) were found in pistachio kernels by Kornsteiner et al. (2006), while a-tocopherol and g-tocopherol (Figure 107.3) were detected by Gentile et al. (2007). Tocopherols are usually called vitamin E, although this name is more correctly assigned to a-tocopherol only (the best antioxidant in this class). Tocopherols react to break the lipid peroxidation that destroys both lipids and neighboring molecules such as proteins and nucleic acids. In pistachio, the sum of b- and g-tocopherols was 293 mg/kg (mean value), and the d-tocopherol mean level was 5 mg/kg (Kornsteiner et al., 2006); however, different values were found in the samples analyzed by Gentile et al. (2007) e means of 0.51 mg/kg for a-tocopherol and 105.4 mg/kg for g-tocopherol. Some flavonoids (Figure 107.4) were found in pistachio kernels and skins by Seeram et al. (2006): two flavones (apigenin and luteolin), two flavanones (naringenin and eriodictyol), and one flavonol and its glycoside (quercetin and rutin). Authors showed that the flavonoids are mainly present in the skins; mean levels were 0.2 and 0.03 mg/kg (apigenin, skins, and

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H3C H3C

CH3

CH3

CH3

CH3

H3C

CH3

CH3

CH3

-Carotene

H3C H3C

CH3

CH3

CH3

CH3

HO

OH

CH3

H3C

CH3

CH3

Lutein

OH

H3C H3C

CH3

CH3

CH3 O

O CH3

H3C

CH3

CH3

CH3

HO

Violaxanthin

OH

H3C CH3

CH3 O

H3C

CH3 CH3

OH

914

H3C

CH3

CH3

CH3

HO

Neoxanthin

OH

H3C H3C

CH3

CH3

CH3

O

O CH3 HO

CH3

H3C

CH3

CH3

Luteoxanthin

FIGURE 107.2 Structures of antioxidants found in pistachio seeds: carotenoids.

whole kernels), 10.0 and 1.04 mg/kg (luteolin, skins, and whole kernels), 1.2 and 0.12 mg/kg (naringenin, skins, and whole kernels), 10.2 and 1.1 mg/kg (eriodictyol, skins, and whole kernels), 14.9 and 0.29 mg/kg (quercetin, skins, and whole kernels), and 1.6 and 0.55 mg/kg (rutin, skins, and whole kernels). Flavonoids like quercetin, rutin, luteolin, and naringenin act as antioxidants and free radical scavengers, and naringenin can reduce oxidative damage to DNA in vitro (Moure et al., 2001). The isoflavones daidzein and genistein (Figure 107.5) were found in pistachio kernels by Gentile et al. (2007). Their amounts were 36.8 and 34.0 mg/kg, respectively; isoflavones are capable of interacting with estrogenic receptors. The same authors reported the presence of vitamin C (Figure 107.5, ascorbic acid; mean value 34.8 mg/kg) and proanthocyanidins (flavan-3-ol polymers) in pistachio kernels. Ascorbate can neutralize several radicals (such as hydroxyl, alcoxyl, peroxyl, glutathione) by hydrogen donation; proanthocyanidins can bind

CHAPTER 107 Antioxidants in Pistachio Seeds

CH3 HO CH3

CH3

CH3

CH3

O

H3C

CH3

CH3

α-Tocopherol H3C HO CH3

CH3

CH3

CH3

O

CH3

H 3C

β-Tocopherol

HO CH3

CH3

CH3

CH3

O

H3C

CH3

γ -Tocopherol

CH3

915

HO CH3

CH3

CH3

CH3

O H3C

CH3

δ-Tocopherol

FIGURE 107.3 Structures of antioxidants found in pistachio seeds: tocopherols.

metals through complexation involving their o-diphenol groups and then inhibit the metalinduced lipid oxidation (Moure et al., 2001). Sixteen different 3-alkylphenols (cardanols, Figure 107.5), mainly monounsaturated, were found in pistachio kernels (Saitta et al., 2009); the total amount of these compounds was evaluated at 213.4 mg/kg (mean value of the kernels). Cardanols are not such strong antioxidants as anacardic acids (Trevisan et al., 2006).

Effects of the use of pistachio nuts on health A study on the antioxidant potential of pistachio nuts showed that hydrophilic extracts inhibited both the metal-dependent and the metal-independent lipid oxidation of bovine liver microsomes, and also the Cu2þ-induced oxidation of human low density lipoproteins, suggesting that these inhibitions are due to a peroxyl radical-scavenging and chelating activity of nut components (Gentile et al., 2007).

PART 2 Effects of Specific Nuts and Seeds

OH OH

HO

O

OH

OH

HO

O

O

OH

Apigenin

O

Luteolin OH OH

OH

HO

O

OH

HO

O

O

OH

Naringenin

O

Eriodictyol OH

OH

OH

OH

916

HO

HO

O

O

O

OH OH

O

Quercetin

OH

Gluc Rham

O

Rutin

FIGURE 107.4 Structures of antioxidants found in pistachio seeds: flavonoids.

Effective studies of the benefits due to pistachio consumption have been conducted on humans and animals (Edwards et al., 1999; Kocyigit et al., 2006; Alturfan et al., 2009). Edwards et al. (1999) evaluated a diet where 20% of the daily caloric intake was pistachio nuts in human patients with moderate hypercholesterolemia; after 3 weeks of this diet, the results showed a moderate decrease in the total cholesterol content, the total cholesterol/HDL ratio, and the LDL/HDL ratio, and an increase in HDL. Kocyigit et al. (2006) conducted a similar study on humans who consumed a regular diet for 1 week before being randomly divided into two groups; one group then used 20% of the daily caloric intake as pistachio nuts in their diet for 3 weeks. In these patients, the mean plasma total cholesterol, malondialdehyde levels, total cholesterol/HDL ratio, and LDL/HDL ratio significantly decreased, while HDL, AOP, and the AOP/MDA ratio significantly increased. Alturfan et al. (2009) evaluated the effects of pistachio consumption in rats fed a high-fat diet for 8 weeks. The rats were divided in two groups: the first group showed increases in total cholesterol, triglycerides, sialic acid, and TBARS, and a decrease in TAA, glutathione, and total thiol levels; the second group, subjected to pistachio consumption, showed significantly decreased levels of triglycerides and TBARS,

CHAPTER 107 Antioxidants in Pistachio Seeds

HO

O

O

HO

O

OH

O

OH

Daidzein

OH

Genistein

HO

R O

O

HO

HO

OH

Ascorbic acid (vitamin C)

OH

3-Alkylphenol (cardanol) (R=alkyl)

FIGURE 107.5 Structures of antioxidants found in pistachio seeds: isoflavones, vitamin C, cardanols.

and increased TAA, demonstrating an improvement in oxidative stress in experimental hyperlipidemia.

ADVERSE EFFECTS AND REACTIONS (ALLERGIES AND TOXICITY) Various nuts and seeds have been reported to contain allergens and produce clinical symptoms of allergy. Pistachio nuts have been cited as causes of urticaria, angioedema, and even anaphylaxis (Perkin, 1990). Members of the Anacardiaceae family characteristically produce a series of compounds based on unsaturated fatty acid precursors. Biosynthetically, usually the CoA ester of palmitoleic acid serves as a precursor of this group of compounds, by chain elongation with three acetate groups; the side chain structure of active compounds can be mono-, di-, or triunsaturated, suggesting that a number of unsaturated acyl-CoA starter units can also be employed. Some pure compounds are very active human allergens, such as the urushiols (3-alkyl-pyrocatechols, biosynthetically derived by anacardic acids after a decarboxylation), which are present in other Anacardiaceae (Saitta et al., 2009).

SUMMARY POINTS l

l

l

l

l

Dietary antioxidants act against oxidative damage, binding metal ions, scavenging radicals, and decomposing peroxides, so these compounds are able to protect cells from free radical damage. Different antioxidant classes are present in pistachio seeds: anthocyanins, tocopherols, carotenoids, chlorophylls, flavonoids, isoflavones, proanthocyanidins, anacardic acids, and cardanols, as well as resveratrol and vitamin C. These antioxidants can interact in very different ways: the synergistic effects can improve the protection against oxidative damage, and play an important role in the biological antioxidant network. Pistachio nut extracts inhibit both the metal-dependent and the metal-independent lipid oxidation of bovine liver microsomes, and also the Cu2þ-induced oxidation of human low density lipoproteins, suggesting these inhibitions are due to a peroxyl radical-scavenging and chelating activity of nut components. Studies of the benefits of pistachio consumption in humans show that the mean plasma total cholesterol and malondialdehyde levels, total cholesterol/high density lipoprotein ratio, and low density lipoprotein/high density lipoprotein ratio significantly decrease,

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while high density lipoproteins, antioxidant potential, and the antioxidant potential/ malondialdehyde ratio significantly increase.

References Alturfan, A. A., Emekli-Alturfan, E., & Uslu, E. (2009). Consumption of pistachio nuts beneficially affected blood lipids and total antioxidant activity in rats fed a high-cholesterol diet. Folia Biologica, 55, 132e136. Bellomo, M. G., & Fallico, B. (2007). Anthocyanins, chlorophylls and xanthophylls in pistachio nuts (Pistacia vera) of different geographic origin. Journal of Food Composition and Analysis, 20, 352e359. Edwards, K., Kwaw, I., Matud, J., & Kurtz, I. (1999). Effect of pistachio nuts on serum lipid levels in patients with moderate hypercholesterolemia. Journal of the American College of Nutrition, 18, 229e232. Gentile, C., Tesoriere, L., Bufera, D., Fazzari, M., Monastero, M., Allegra, M., et al. (2007). Antioxidant activity of Sicilian pistachio (Pistacia vera L. var. Bronte) nut extract and its bioactive components. Journal of Agricultural and Food Chemistry, 55, 643e648. Giuffrida, D., Saitta, M., La Torre, G. L., Bombaci, L., & Dugo, G. (2006). Carotenoid, chlorophyll and chlorophyllderived compounds in pistachio kernels (Pistacia vera L.) from Sicily. Italian Journal of Food Science, 18, 309e316. Goli, A. H., Barzegar, M., & Sahari, M. A. (2005). Antioxidant activity and total phenolic compounds of pistachio (Pistacia vera) hull extracts. Food Chemistry, 92, 521e525. Grippi, F., Crosta, L., Aiello, G., Tolomeo, M., Oliveti, F., Gebbia, N., et al. (2008). Determination of stilbenes in Sicilian pistachio by high-performance liquid chromatographic diode array (HPLC-DAD/FLD) and evaluation of eventually mycotoxin contamination. Food Chemistry, 107, 483e488. Hormaza, J. I., & Wunsch, A. (2007). Pistachio. In C. Kole (Ed.), Genome mapping and molecular breeding in plants. Vol. 4, Fruits and nuts (pp. 243e252). Berlin, Germany: SpringereVerlag. Kocyigit, A., Koylu, A. A., & Keles, H. (2006). Effects of pistachio nuts consumption on plasma lipid profile and oxidative status in healthy volunteers. Nutrition Metabolism & Cardiovascular Diseases, 16, 202e209. Kornsteiner, M., Wagner, K. H., & Elmadfa, I. (2006). Tocopherols and total phenolics in 10 different nut types. Food Chemistry, 98, 381e387. Miniati, E. (1981). Anthocyanin pigment in the pistachio nut. Fitoterapia, 52, 267e271.

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Moure, A., Cruz, J. M., Franco, D., Dominguez, J. M., Sineiro, J., Dominguez, H., et al. (2001). Natural antioxidants from residual sources. Food Chemistry, 72, 145e171. Perkin, J. E. (1990). Major food allergens and principle of dietary management. In J. E. Perkin (Ed.), Food allergies and adverse reactions (pp. 51e68). Gaithersburg, MD: Aspen Publishers. Seeram, N. P., Zhang, Y., Henning, S. M., Lee, R., Niu, Y., Lin, G., et al. (2006). Pistachio skin phenolics are destroyed by bleaching resulting in reduced antioxidative capacities. Journal of Agricultural and Food Chemistry, 54, 7036e7040. Saitta, M., Giuffrida, D., La Torre, G. L., Potortı`, A. G., & Dugo, G. (2009). Characterisation of alkylphenols in pistachio (Pistacia vera L.) kernels. Food Chemistry, 117, 451e455. Tokusoglu, O., Unal, M. U., & Yemis, F. (2005). Determination of the phytoalexin resveratrol (3,5,40 -trihydroxystilbene) in peanuts and pistachios by high-performance liquid chromatographic diode array (HPLC-DAD) and gas chromatography-mass spectrometry (GC-MS). Journal of Agricultural and Food Chemistry, 53, 5003e5009. Trevisan, M. T. S., Pfundstein, B., Haubner, R., Wurtele, G., Spiegelhalder, B., Bartsch, H., et al. (2006). Characterization of alkyl phenols in cashew (Anacardium occidentale) products and assay of their antioxidant capacity. Food Chemistry and Toxicology, 44, 188e197. Wu, X., & Prior, R. L. (2005). Identification and characterization of anthocyanins by high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry in common foods in the United States: vegetables, nuts, and grains. Journal of Agricultural and Food Chemistry, 53, 3101e3113. Yalpani, M., & Tyman, J. H. P. (1983). The phenolic acids of Pistacia vera. Phytochemistry, 22, 2263e2266.