- Email: [email protected]
Indole alkaloids from the seeds of Centaurea cyanus (Asteraceae)
Phytochemistry 57 (2001) 1273–1276 www.elsevier.com/locate/phytochem
Indole alkaloids from the seeds of Centaurea cyanus (Asteraceae) Satyajit D. Sarkera,*, Anuszka Lairda, Lutfun Naharb, Yashodharan Kumarasamya, Marcel Jasparsc a School of Pharmacy, The Robert Gordon University, Schoolhill, Aberdeen AB10 1FR, Scotland, UK Japp Laboratory, Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, Aberdeen AB24 3UE, Scotland, UK c Marine Natural Products Laboratory, Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, Aberdeen AB24 3UE, Scotland, UK
b
Received 11 January 2001; received in revised form 22 February 2001
Abstract Preparative RP-HPLC analysis of a methanol extract of the seeds of Centaurea cyanus afforded four indole alkaloids: moschamine, cis-moschamine, centcyamine and cis-centcyamine, the latter two being new natural products. Structures of these compounds were elucidated by comprehensive spectroscopic analyses. General toxicity of the isolates was determined by Brine Shrimp Lethality bioassay. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Centaurea cyanus; Compositae; Asteraceae; Indole; Moschamine; Centcyamine; Toxicity; Brine Shrimp Lethality bioassay; Artemia salina; NMR
1. Introduction Centaurea cyanus L. (family: Asteraceae alt. Compositae), commonly known as ‘‘Cornflower’’ or ‘‘Bachelor’s button’’, is a flowering weed indigenous to Iran, Iraq, Turkey and Pakistan in Asia, and Albania, Bulgaria, Greece, Italy and the former Yugoslavia in Europe, and also cultivated and naturalised in many other parts of the world (GRIN database, 2000). Flower-heads of this plant are well-known crude drugs used in European traditional medicine in the treatment of minor ocular inflammation (Bruneton, 1995), and as diuretic and cholagogic agents (Mashkovskii, 1984; Litvinenko and Bubenchikova, 1988). Antimicrobial (Monya et al., 1968), antiinflammatory and immunological activities (Garbacki et al., 1999) of C. cyanus flowers have also been reported. Previous phytochemical studies on C. cyanus revealed the presence of various types of plant secondary metabolites, e.g. anthocyanins, flavonoid and their glycosides, phenolcarboxylic acids, sesquiterpenes, coumarins, etc. (Dictionary of Natural Products, 1999; Phytochemical and Ethnobotanical database, 2000; ISI * Corresponding author. Tel.: +44-1224-262547; fax: +44-1224262555. E-mail address: [email protected] (S.D. Sarker).
database, 2000). We now report on the isolation, structure determination and general toxicity (in Brine Shrimp Lethality bioassay) of four indole alkaloids from the seeds of C. cyanus.
2. Results and discussion RP-HPLC analysis of the MeOH extract of the seeds of C. cyanus yielded four indole alkaloids which, on the basis of extensive spectroscopic analyses (e.g. UV, LSIMS, and 1D and 2D NMR), were characterised as moschamine (1), cis-moschamine (2), (E) N-(4-hydroxycinnamoyl)-5-metho xytryptamine (3) and (Z) N-(4-hydroxycinnamoyl)-5methoxytryptamine (4). Compounds 3 and 4 were found to be new natural products and named, respectively, centcyamine and cis-centcyamine. All four compounds show positive colour reactions with Dragendorff’s reagent. Their UV absorption maxima are similar to those of indole alkaloids reported previously from C. moschata (Sarker et al., 1997). In fact, the UV absorption maxima of the mixture (45:55) of 1 and 2 are identical to those previously published for moschamine and cis-moschamine (Sarker et al., 1997). 1 H and 13C NMR data of 1 and 2 also match published data (Sarker et al., 1997). LSIMS and 2D-NMR
0031-9422/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0031-9422(01)00084-X
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S.D. Sarker et al. / Phytochemistry 57 (2001) 1273–1276 Table 1 1 H and 13C NMR data of compounds 3 and 4 (coupling constant J=Hz in parentheses) Carbon no.
H a
C a
3 2 3 3a 4 5 5-MeO 6 7 7a a-CH2 b-CH2 10 20 30 40 50 60 70 80 90 a
experiments, e.g. COSY, HSQC and HMBC further confirmed the identities of 1 and 2 as moschamine and cis-moschamine respectively. Compounds 3 and 4 were also isolated as an approximately 45:55 mixture of cis-trans isomers. Two wellseparated peaks could be observed in the RP-HPLC, but on isolation they readily formed the mixture again. Owing to this unavoidable situation, all spectroscopic analyses on 3 and 4 were performed on the mixture. A LSI mass spectrum revealed [M+H]+ (positive ion mode) ion peak at m/z 337, suggesting Mr=336 and solving for C20H20N2O3. 1H and 13C NMR spectra (Table 1) for this mixture were similar to those for 1 and 2 with the exception that instead of a 3-methoxy-4hydroxyphenyl, a 4-hydroxyphenyl moiety was present in 3 and 4. In addition, instead of a 5-hydroxytryptamine (in 1 and 2), a 5-methoxytryptamine formed the amide linkage with 4-hydroxycinnamoyl moiety 3 and 4. 1H–1H COSY revealed 4 different spin systems: H-7$H-6$H-4, H2-a$H2-b, H-70 $H-80 and H-20 (H-60 )$H-30 (H-50 ).
6.91 – – 6.92 – 3.81 6.64 7.12 – 3.53 2.89 – 7.35 6.74 – 6.74 7.35 7.42 6.36 –
4 s
d (2.3) s dd (2.3, 8.6) d (8.6) t (7.1) t (7.1) d (8.2) d (8.2) d d d d
(8.2) (8.2) (15.7) (15.7)
6.99 – – 6.93 – 3.79 6.62 7.10 – 3.45 2.82 – 7.32 6.66 – 6.66 7.32 6.58 5.78 –
s
d (2.3) s dd (2.3, 8.6) d (8.6) t (7.1) t (7.1) d (8.2) d (8.2) d d d d
(8.2) (8.2) (12.7) (12.7)
3
4
123.0 111.1 128.0 102.2 148.8 55.1 111.0 111.2 132.0 40.1 25.0 127.0 129.8 114.6 160.0 114.6 129.8 140.5 117.5 167.8
122.8 111.1 128.0 102.0 148.8 55.0 111.0 111.2 132.0 39.9 24.8 127.1 133.6 115.1 159.5 115.1 133.6 136.7 120.4 169.0
in ppm.
All methyl, methylene and methine carbons were unambiguously assigned from 1H–13C direct correlation observed in HSQC spectrum. The most crucial 1H–13C long-range correlation observed in HMBC (Fig. 1) was the 3J correlation from the methoxyl protons (H 3.81/ 3.79) to the oxygenated aromatic carbon C-5 (C 148.8) which was related (3J) to H-7 (H 7.12/7.10). The amide linkage was confirmed from the 3J correlation from H2a (H 3.53/3.45) to the carbonyl carbon (C-90 , C 167.8/ 169.0). Thus a combination of 1D and 2D NMR techniques allowed the unambiguous characterisation of compounds 3 and 4. Compounds 1 and 2 were previously isolated from another species, C. moschata, but to our knowledge, 3 and 4 are new natural products. Compounds arising from the amide formation between tryptamine (or serotonin) and cinnamic acid (or derivatives) have also been observed in few other species of the family Compositae (Dictionary of Natural Products, 1999). The co-occurence of moschamine (1) and cismoschamine (2) both in C. cyanus and C. moschata might be significant from chemotaxonomic viewpoint Both mixtures, 1 and 2, and 3 and 4 showed significant toxicity in Brine Shrimp (Artemia salina) Lethality bioassay (Meyer et al., 1982). The LD50s for these geometrical isomeric mixtures 1 and 2, and 3 and 4 were determined, respectively, 21.65 and 14.43 mg/ml. The observed lethality induced by these compounds is comparable to that published for berberine chloride (LD50= 22.5 mg /ml) (Meyer et al., 1982), and both the mixtures
S.D. Sarker et al. / Phytochemistry 57 (2001) 1273–1276
1275
3.4. Isolation of compounds The MeOH extract was fractionated on a Sep-Pak, using 20, 40, 60, 80 and 100% MeOH–water mixture (150 ml each) as eluent. Preparative RP-HPLC (isocratic, 32% MeOH in water, 15 ml/min) of the Sep-Pak fraction (40% MeOH in water) yielded compounds 1 and 2 as a mixture (45:55, 3.5 mg), and 3 and 4 also as a similar mixture (45:55, 2.1 mg). 3.5. Moschamine [(E) N-(3-methoxy-4hydroxycinnamoyl)-5-hydroxytryptamine, 1]+cismoschamine [(Z) N-(3-methoxy-4-hydroxycinnamoyl)5-hydroxytryptamine, 2] Fig. 1. 1H–13C long-range correlations observed in HMBC of 3.
are more than 3 times more toxic than strychnine sulfate (LD50=77.2 mg/ml).
3. Experimental
Amorphous. UV, 1H and 13C NMR (Sarker et al., 1997). LSIMS (positive ion mode) m/z 353 [M+H]+. 3.6. Centcyamine [(E) N-(4-hydroxycinnamoyl)-5methoxytryptamine, 3]+cis- centcyamine [(Z) N(4-hydroxycinnamoyl)-5-methoxytryptamine, 4] Amorphous. UV lmax nm: 224, 287, 296, 312. 1H- and C NMR (Tables 1). LSIMS (positive ion mode) m/z 337 [M+H]+.
13
3.1. General 3.7. Brine Shrimp (Artemia salina) Lethality bioassay UV spectra were obtained in MeOH. NMR spectra were recorded in CD3OD using a Varian Unity INOVA 400 MHz NMR Spectrometer. LSIMS (positive ion mode); glycerol matrix using a Cs+ primary ion beam on a VG Quattro triple quadrupole mass spectrometer (VG Biotech. Altrincham, UK). HPLC separation was performed in the Dionex prep-HPLC System coupled with Gynkotek GINA50 autosampler and Dionex UVD340S Photo-Diode-Array detector. RP stands for reversed-phase C18 column. Sep-Pak Vac 35 cc (10 g) C18 cartridge (Waters) was used for pre-HPLC fractionation.
Brine shrimp eggs were purchased from Pet Shop, Kittybrewster, Aberdeen, UK. The bioassay was conducted following the procedure published previously (Meyer et al., 1982). LD50s were determined from the 24 h counts using the probit analysis method (Finney, 1971). Percentage mortalities were adjusted relative to the natural mortality rate of the control, following Abbots formula P ¼ Pi C=1 C, where P denotes the observed nonzero mortality rate and C represents the mortality rate of the control.
3.2. Plant material
Acknowledgements
Seeds of C. cyanus L. (catalogue no: 304 A) were purchased from commercial source (Chiltern Seeds, Bortree Stile, Ulverston, Cumbria LA12 7PB, UK), and a voucher specimen (CA2000005) representing this purchase has been generated in the School of Pharmacy, The Robert Gordon University, Aberdeen, UK.
We thank Russell S. Gray (Department of Chemistry, University of Aberdeen, Aberdeen, UK) for NMR analyses.
3.3. Extraction Ground seeds (11.0 g) of C. cyanaus were Soxhletextracted successively with n-hexane, dichloromethane and MeOH. All these extracts were separately concentrated using a rotary evaporator at a maximum temperature of 45 C.
References Bruneton, J., 1995. Pharmacognosy, Phytochemistry, Medicinal Plants. Tec-Doc Lavoisier, Paris, New York, pp. 310. Dictionary of Natural Products (DNP) on CD-ROM, 1999. release 8:1, Chapman and Hall, Boca Raton, FL. Finney, D.J., 1971. Probit Analysis, 3rd Edition. Cambridge University Press, Cambridge. Garbacki, N., Gloaguen, V., Damas, J., Bodart, P., Tits, M., Angenot, L., 1999. Antiinflammatory and immunological effects of Centaurea cyanus flower heads. J. Ethnopharmacology 68, 235.
1276
S.D. Sarker et al. / Phytochemistry 57 (2001) 1273–1276
GRIN database, 2000. USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network (GRIN), National Germplasm Resources Laboratory, Beltsville, Maryland, USA. Available on-line at: http/www.ars-grin.gov/cgi-bin/npgs/ html/tax_search.pl?Centaurea+cyanus. ISI database, 2000. Institute for Scientific Information, UK. Available on-line through Web of Science at: http://wos.mimas.ac.uk. Litvinenko, V.I., Bubenchikova, V.N., 1988. Phytochemical study of Centaurea cyanus. Khimiya Prirodnykh Soedinenii 6, 792. Mashkovskii, M.D., 1984. Medicinal Plants, Vol. 1. Meditsina, Moscow, 499 pp. Meyer, B.N., Ferrigni, N.R., Putnam, J.E., Jacobson, L.B., Nicholas,
D.E., McLaughlin, J.L., 1982. Brine shrimp: a convenient general bioassay for active plant constituents. Planta Medica 45, 31. Monya, K., Sabau, M., Racz, G., 1968. Antibiotic effect of extracts from Centaurea. Planta Medica 16, 58. Phytochemical and Ethnobotanical Database, 2000. USDA-ARSNGRL, Bletsville Agricultural Research Center, Beltsville, Maryland, USA. Available on-line at: http://www.ars-grin/cgi-bib/duke/ pharmacy2.pl. Sarker, S.D., Savchenko, T., Whiting, P., Sik, V., Dinan, L., 1997. Moschamine, cis-moschamine, moschamindole and moschamindolol: four novel indole alkaloids from Centaurea moschata. Nat. Prod. Lett. 9, 189.
Indole alkaloids from the seeds of Centaurea cyanus (Asteraceae) Satyajit D. Sarkera,*, Anuszka Lairda, Lutfun Naharb, Yashodharan Kumarasamya, Marcel Jasparsc a School of Pharmacy, The Robert Gordon University, Schoolhill, Aberdeen AB10 1FR, Scotland, UK Japp Laboratory, Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, Aberdeen AB24 3UE, Scotland, UK c Marine Natural Products Laboratory, Department of Chemistry, University of Aberdeen, Meston Walk, Old Aberdeen, Aberdeen AB24 3UE, Scotland, UK
b
Received 11 January 2001; received in revised form 22 February 2001
Abstract Preparative RP-HPLC analysis of a methanol extract of the seeds of Centaurea cyanus afforded four indole alkaloids: moschamine, cis-moschamine, centcyamine and cis-centcyamine, the latter two being new natural products. Structures of these compounds were elucidated by comprehensive spectroscopic analyses. General toxicity of the isolates was determined by Brine Shrimp Lethality bioassay. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Centaurea cyanus; Compositae; Asteraceae; Indole; Moschamine; Centcyamine; Toxicity; Brine Shrimp Lethality bioassay; Artemia salina; NMR
1. Introduction Centaurea cyanus L. (family: Asteraceae alt. Compositae), commonly known as ‘‘Cornflower’’ or ‘‘Bachelor’s button’’, is a flowering weed indigenous to Iran, Iraq, Turkey and Pakistan in Asia, and Albania, Bulgaria, Greece, Italy and the former Yugoslavia in Europe, and also cultivated and naturalised in many other parts of the world (GRIN database, 2000). Flower-heads of this plant are well-known crude drugs used in European traditional medicine in the treatment of minor ocular inflammation (Bruneton, 1995), and as diuretic and cholagogic agents (Mashkovskii, 1984; Litvinenko and Bubenchikova, 1988). Antimicrobial (Monya et al., 1968), antiinflammatory and immunological activities (Garbacki et al., 1999) of C. cyanus flowers have also been reported. Previous phytochemical studies on C. cyanus revealed the presence of various types of plant secondary metabolites, e.g. anthocyanins, flavonoid and their glycosides, phenolcarboxylic acids, sesquiterpenes, coumarins, etc. (Dictionary of Natural Products, 1999; Phytochemical and Ethnobotanical database, 2000; ISI * Corresponding author. Tel.: +44-1224-262547; fax: +44-1224262555. E-mail address: [email protected] (S.D. Sarker).
database, 2000). We now report on the isolation, structure determination and general toxicity (in Brine Shrimp Lethality bioassay) of four indole alkaloids from the seeds of C. cyanus.
2. Results and discussion RP-HPLC analysis of the MeOH extract of the seeds of C. cyanus yielded four indole alkaloids which, on the basis of extensive spectroscopic analyses (e.g. UV, LSIMS, and 1D and 2D NMR), were characterised as moschamine (1), cis-moschamine (2), (E) N-(4-hydroxycinnamoyl)-5-metho xytryptamine (3) and (Z) N-(4-hydroxycinnamoyl)-5methoxytryptamine (4). Compounds 3 and 4 were found to be new natural products and named, respectively, centcyamine and cis-centcyamine. All four compounds show positive colour reactions with Dragendorff’s reagent. Their UV absorption maxima are similar to those of indole alkaloids reported previously from C. moschata (Sarker et al., 1997). In fact, the UV absorption maxima of the mixture (45:55) of 1 and 2 are identical to those previously published for moschamine and cis-moschamine (Sarker et al., 1997). 1 H and 13C NMR data of 1 and 2 also match published data (Sarker et al., 1997). LSIMS and 2D-NMR
0031-9422/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0031-9422(01)00084-X
1274
S.D. Sarker et al. / Phytochemistry 57 (2001) 1273–1276 Table 1 1 H and 13C NMR data of compounds 3 and 4 (coupling constant J=Hz in parentheses) Carbon no.
H a
C a
3 2 3 3a 4 5 5-MeO 6 7 7a a-CH2 b-CH2 10 20 30 40 50 60 70 80 90 a
experiments, e.g. COSY, HSQC and HMBC further confirmed the identities of 1 and 2 as moschamine and cis-moschamine respectively. Compounds 3 and 4 were also isolated as an approximately 45:55 mixture of cis-trans isomers. Two wellseparated peaks could be observed in the RP-HPLC, but on isolation they readily formed the mixture again. Owing to this unavoidable situation, all spectroscopic analyses on 3 and 4 were performed on the mixture. A LSI mass spectrum revealed [M+H]+ (positive ion mode) ion peak at m/z 337, suggesting Mr=336 and solving for C20H20N2O3. 1H and 13C NMR spectra (Table 1) for this mixture were similar to those for 1 and 2 with the exception that instead of a 3-methoxy-4hydroxyphenyl, a 4-hydroxyphenyl moiety was present in 3 and 4. In addition, instead of a 5-hydroxytryptamine (in 1 and 2), a 5-methoxytryptamine formed the amide linkage with 4-hydroxycinnamoyl moiety 3 and 4. 1H–1H COSY revealed 4 different spin systems: H-7$H-6$H-4, H2-a$H2-b, H-70 $H-80 and H-20 (H-60 )$H-30 (H-50 ).
6.91 – – 6.92 – 3.81 6.64 7.12 – 3.53 2.89 – 7.35 6.74 – 6.74 7.35 7.42 6.36 –
4 s
d (2.3) s dd (2.3, 8.6) d (8.6) t (7.1) t (7.1) d (8.2) d (8.2) d d d d
(8.2) (8.2) (15.7) (15.7)
6.99 – – 6.93 – 3.79 6.62 7.10 – 3.45 2.82 – 7.32 6.66 – 6.66 7.32 6.58 5.78 –
s
d (2.3) s dd (2.3, 8.6) d (8.6) t (7.1) t (7.1) d (8.2) d (8.2) d d d d
(8.2) (8.2) (12.7) (12.7)
3
4
123.0 111.1 128.0 102.2 148.8 55.1 111.0 111.2 132.0 40.1 25.0 127.0 129.8 114.6 160.0 114.6 129.8 140.5 117.5 167.8
122.8 111.1 128.0 102.0 148.8 55.0 111.0 111.2 132.0 39.9 24.8 127.1 133.6 115.1 159.5 115.1 133.6 136.7 120.4 169.0
in ppm.
All methyl, methylene and methine carbons were unambiguously assigned from 1H–13C direct correlation observed in HSQC spectrum. The most crucial 1H–13C long-range correlation observed in HMBC (Fig. 1) was the 3J correlation from the methoxyl protons (H 3.81/ 3.79) to the oxygenated aromatic carbon C-5 (C 148.8) which was related (3J) to H-7 (H 7.12/7.10). The amide linkage was confirmed from the 3J correlation from H2a (H 3.53/3.45) to the carbonyl carbon (C-90 , C 167.8/ 169.0). Thus a combination of 1D and 2D NMR techniques allowed the unambiguous characterisation of compounds 3 and 4. Compounds 1 and 2 were previously isolated from another species, C. moschata, but to our knowledge, 3 and 4 are new natural products. Compounds arising from the amide formation between tryptamine (or serotonin) and cinnamic acid (or derivatives) have also been observed in few other species of the family Compositae (Dictionary of Natural Products, 1999). The co-occurence of moschamine (1) and cismoschamine (2) both in C. cyanus and C. moschata might be significant from chemotaxonomic viewpoint Both mixtures, 1 and 2, and 3 and 4 showed significant toxicity in Brine Shrimp (Artemia salina) Lethality bioassay (Meyer et al., 1982). The LD50s for these geometrical isomeric mixtures 1 and 2, and 3 and 4 were determined, respectively, 21.65 and 14.43 mg/ml. The observed lethality induced by these compounds is comparable to that published for berberine chloride (LD50= 22.5 mg /ml) (Meyer et al., 1982), and both the mixtures
S.D. Sarker et al. / Phytochemistry 57 (2001) 1273–1276
1275
3.4. Isolation of compounds The MeOH extract was fractionated on a Sep-Pak, using 20, 40, 60, 80 and 100% MeOH–water mixture (150 ml each) as eluent. Preparative RP-HPLC (isocratic, 32% MeOH in water, 15 ml/min) of the Sep-Pak fraction (40% MeOH in water) yielded compounds 1 and 2 as a mixture (45:55, 3.5 mg), and 3 and 4 also as a similar mixture (45:55, 2.1 mg). 3.5. Moschamine [(E) N-(3-methoxy-4hydroxycinnamoyl)-5-hydroxytryptamine, 1]+cismoschamine [(Z) N-(3-methoxy-4-hydroxycinnamoyl)5-hydroxytryptamine, 2] Fig. 1. 1H–13C long-range correlations observed in HMBC of 3.
are more than 3 times more toxic than strychnine sulfate (LD50=77.2 mg/ml).
3. Experimental
Amorphous. UV, 1H and 13C NMR (Sarker et al., 1997). LSIMS (positive ion mode) m/z 353 [M+H]+. 3.6. Centcyamine [(E) N-(4-hydroxycinnamoyl)-5methoxytryptamine, 3]+cis- centcyamine [(Z) N(4-hydroxycinnamoyl)-5-methoxytryptamine, 4] Amorphous. UV lmax nm: 224, 287, 296, 312. 1H- and C NMR (Tables 1). LSIMS (positive ion mode) m/z 337 [M+H]+.
13
3.1. General 3.7. Brine Shrimp (Artemia salina) Lethality bioassay UV spectra were obtained in MeOH. NMR spectra were recorded in CD3OD using a Varian Unity INOVA 400 MHz NMR Spectrometer. LSIMS (positive ion mode); glycerol matrix using a Cs+ primary ion beam on a VG Quattro triple quadrupole mass spectrometer (VG Biotech. Altrincham, UK). HPLC separation was performed in the Dionex prep-HPLC System coupled with Gynkotek GINA50 autosampler and Dionex UVD340S Photo-Diode-Array detector. RP stands for reversed-phase C18 column. Sep-Pak Vac 35 cc (10 g) C18 cartridge (Waters) was used for pre-HPLC fractionation.
Brine shrimp eggs were purchased from Pet Shop, Kittybrewster, Aberdeen, UK. The bioassay was conducted following the procedure published previously (Meyer et al., 1982). LD50s were determined from the 24 h counts using the probit analysis method (Finney, 1971). Percentage mortalities were adjusted relative to the natural mortality rate of the control, following Abbots formula P ¼ Pi C=1 C, where P denotes the observed nonzero mortality rate and C represents the mortality rate of the control.
3.2. Plant material
Acknowledgements
Seeds of C. cyanus L. (catalogue no: 304 A) were purchased from commercial source (Chiltern Seeds, Bortree Stile, Ulverston, Cumbria LA12 7PB, UK), and a voucher specimen (CA2000005) representing this purchase has been generated in the School of Pharmacy, The Robert Gordon University, Aberdeen, UK.
We thank Russell S. Gray (Department of Chemistry, University of Aberdeen, Aberdeen, UK) for NMR analyses.
3.3. Extraction Ground seeds (11.0 g) of C. cyanaus were Soxhletextracted successively with n-hexane, dichloromethane and MeOH. All these extracts were separately concentrated using a rotary evaporator at a maximum temperature of 45 C.
References Bruneton, J., 1995. Pharmacognosy, Phytochemistry, Medicinal Plants. Tec-Doc Lavoisier, Paris, New York, pp. 310. Dictionary of Natural Products (DNP) on CD-ROM, 1999. release 8:1, Chapman and Hall, Boca Raton, FL. Finney, D.J., 1971. Probit Analysis, 3rd Edition. Cambridge University Press, Cambridge. Garbacki, N., Gloaguen, V., Damas, J., Bodart, P., Tits, M., Angenot, L., 1999. Antiinflammatory and immunological effects of Centaurea cyanus flower heads. J. Ethnopharmacology 68, 235.
1276
S.D. Sarker et al. / Phytochemistry 57 (2001) 1273–1276
GRIN database, 2000. USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network (GRIN), National Germplasm Resources Laboratory, Beltsville, Maryland, USA. Available on-line at: http/www.ars-grin.gov/cgi-bin/npgs/ html/tax_search.pl?Centaurea+cyanus. ISI database, 2000. Institute for Scientific Information, UK. Available on-line through Web of Science at: http://wos.mimas.ac.uk. Litvinenko, V.I., Bubenchikova, V.N., 1988. Phytochemical study of Centaurea cyanus. Khimiya Prirodnykh Soedinenii 6, 792. Mashkovskii, M.D., 1984. Medicinal Plants, Vol. 1. Meditsina, Moscow, 499 pp. Meyer, B.N., Ferrigni, N.R., Putnam, J.E., Jacobson, L.B., Nicholas,
D.E., McLaughlin, J.L., 1982. Brine shrimp: a convenient general bioassay for active plant constituents. Planta Medica 45, 31. Monya, K., Sabau, M., Racz, G., 1968. Antibiotic effect of extracts from Centaurea. Planta Medica 16, 58. Phytochemical and Ethnobotanical Database, 2000. USDA-ARSNGRL, Bletsville Agricultural Research Center, Beltsville, Maryland, USA. Available on-line at: http://www.ars-grin/cgi-bib/duke/ pharmacy2.pl. Sarker, S.D., Savchenko, T., Whiting, P., Sik, V., Dinan, L., 1997. Moschamine, cis-moschamine, moschamindole and moschamindolol: four novel indole alkaloids from Centaurea moschata. Nat. Prod. Lett. 9, 189.