- Email: [email protected]
Flavanones and stilbenes from Cyperus stoloniferus Retz.
Biochemical Systematics and Ecology 50 (2013) 220–222
Contents lists available at SciVerse ScienceDirect
Biochemical Systematics and Ecology journal homepage: www.elsevier.com/locate/biochemsyseco
Flavanones and stilbenes from Cyperus stoloniferus Retz. Nguyen Minh Chau a, b, Tran Thi Hong Hanh a, Nguyen Thi Luyen a, Chau Van Minh a, Nguyen Tien Dat a, * a b
Institute of Marine Biochemistry, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Cau Giay, Hanoi, Viet Nam School of Chemical Engineering, Hanoi University of Science and Technology, 1-Dai Co Viet Road, Hanoi, Viet Nam
a r t i c l e i n f o Article history: Received 13 January 2013 Accepted 13 April 2013 Available online 15 May 2013 Keywords: Cyperus stoloniferus Cyperaceae C-methylflavonoid Stilbene Piceatannol
1. Subject and source Cyperus stoloniferus Retz. (Cyperaceae) widely grows in the coastal zones in Vietnam and has been used for treatment of menstrual disorders, dysmenorrhoea, stomachache, and inflammation (Vo, 2004). The rhizomes of C. stoloniferus were collected in Tien Hai, Thai Binh on June, 2011 and identified by Prof. Tran Huy Thai, Institute of Ecology and Biological Resources (IEBR), Vietnam Academy of Science and Technology (VAST). Voucher specimens have been deposited at the herbarium of the IEBR. 2. Previous work Although C. stoloniferus has shown similar pharmacological effects with C. rotundus in Vietnamese folk medicine (Vo, 2004), there are very few reports on the chemical composition and biological activity of this plant. Only three studies on the essential oil composition (Tran and Tran, 2012; Nguyen et al., 1995) and the analgesic activity (Vu and Mai, 1994) of C. stoloniferus were reported so far. 3. Present study The air-dried and powdered materials (2.5 kg) were extracted with methanol (6 L 3 times) in a sonic bath for 30 min. The combined extracts were concentrated under a vacuum to obtain a crude residue (210 g), which was then resuspended in water (1 L), and successively extracted by chloroform and ethyl acetate (each 1 L 3 times). The organic layers were
* Corresponding author. Tel.: þ84 4 37917049; fax: þ84 4 37917054. E-mail addresses: [email protected], [email protected] (N.T. Dat). 0305-1978/$ – see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.bse.2013.04.004
N.M. Chau et al. / Biochemical Systematics and Ecology 50 (2013) 220–222
221
concentrated to give 80.1 g and 47.7 g of chloroform and ethyl acetate residues, respectively. The chloroform residue was chromatographed on a silica gel column eluted by a gradient of 1–100% acetone in hexane to afford five fractions C1-5. Compound 1 (8.0 mg) was purified from C4 by a C18 column using a mobile phase of acetone-water (1:1 v/v). The ethyl acetate residue was chromatographed on a silica gel column eluted by a gradient of 1–100% methanol in chloroform to afford three fractions E1-3. The E1 was passed through a silica gel column eluted by hexane-chloroform-methanol (1:2:0.3 v/v) to obtain 4 (5.7 mg). A silica gel column chromatography of the fraction E2 using chloroform-methanol (20:1 v/v) as eluant afforded three subfractions E2a-c. Compound 2 (9.8 mg) was purified from E2a by a Sephadex LH-20 column eluted by a mobile phase of methanol-water (1:1 v/v). Compound 3 (4.5 g) was obtained by recrystallization in methanol from E2b. Compound 1 was obtained as a yellow solid. Its HRESIMS revealed the peak at m/z 347.1109 [M þ H]þ corresponding to the molecular formula C18H19O7. The 1H-NMR spectrum of 1 showed three aromatic singlets at dH 5.97 (1H, s, H-8), 6.69 (1H, s, H30 ) and 7.00 (1H, s, H-60 ), methine-methylene coupled protons at dH 5.62 (1H, dd, J ¼ 3.0, 13.0 Hz, H-2), 2.70 (1H, dd, J ¼ 3.0, 17.0 Hz, Ha-3) and 2.95 (1H, dd, J ¼ 13.0, 17.0 Hz, Hb-3). In addition, two methoxy and a C-methyl singlets were observed at dH 3.83 (3H, br s, 20 -OMe), 3.90 (3H, br s, 40 -OMe) and 1.97 (3H, br s, 6-Me). The 13C-NMR and DEPT spectra of 1 indicated the presence of three CH3, a CH2, four CH and ten quaternary carbon signals. The flavanone skeleton of 1 was recognized by the signals of a carbonyl group (dC 198.0, C-4), an oxymethine (dC 75.2, C-2) and a methylene (dC 43.4, C-3). The HMBC correlations (Fig. 1) from H-8 (dH 5.97) to dC 105.3 (C-6), 166.1 (C-7), 162.6 (C-9), and 103.0 (C-10), and from the methyl signal (dH 1.97) to dC 162.6 (C-5), 105.3 (C-6), and 166.1 (C-7) confirmed that the methyl group was located at C-6 in the A-ring. For the B-ring, two aromatic protons at dH 6.69 and 7.00 were all observed as singlets and showed any HMBC correlation each other indicating that they were located in para positions, i.e. H-30 and H-60 . The NOESY cross peaks between both methoxy signals and H-30 (dH 6.69) (Fig. 1) indicated that these two methoxy groups attached to C-20 and C-40 . The HMBC couplings from H-2 (dH 5.62) to C10 (dC 120.5) and C-20 (dC 151.5), and from H-60 (dH 7.00) to C-2 (dC 75.2), C-10 (dC 120.5), and C-20 (dC 151.5) allowed the NMR assignments of the B-ring. The negative optical rotation of 1 and a negative Cotton effects effect at 295 nm indicated the Sconfiguration at C-2 (Mustafa et al., 2005; Slade et al., 2005). Accordingly, compound 1 was newly elucidated to be (S)-5,50 ,7trihydroxy-20 ,40 -dimethoxy-6-methylflavanone. 3.1. (S)-5,50 ,7-trihydroxy-20 ,40 -dimethoxy-6-methylflavanone (1) 3 Yellow powder, ½a 25 M, MeOH) lmax(Dε) nm 295 (13.7), 345 (þ2.1); UV (MeOH) D ¼ –88.0 (c 0.1, MeOH); CD (c 1.4 10 lmax (log ε) 232 (3.35), 290 (3.44) nm; IR nmax(KBr): 3393, 1637, 1516, 1303, 1158 cm-1; 1H NMR (500 MHz, CD3OD): d 5.62 (1H, dd, J ¼ 3.0, 13.0 Hz, H-2), 2.70 (1H, dd, J ¼ 3.0, 17.0 Hz, H-3a), 2.95 (1H, dd, J ¼ 13.0, 17.0 Hz, H-3b), 5.97 (1H, s, H-8), 6.69 (1H, s, H-30 ), 7.00 (1H, s, H-60 ), 1.97 (3H, s, CH3), 3.83 (3H, s, 20 -OCH3), 3.90 (3H, s, 40 -OCH3); 13C NMR (125 MHz, CD3OD): d 75.2 (C-2),
Fig. 1. The structures of compounds 1–4 and key HMBC (/) and NOESY (4) correlations of 1.
222
N.M. Chau et al. / Biochemical Systematics and Ecology 50 (2013) 220–222
43.4 (C-3), 198.0 (C-4), 162.6 (C-5), 105.3 (C-6), 166.1 (C-7), 95.2 (C-8), 162.6 (C-9), 103.0 (C-10), 120.5 (C-10 ), 151.2 (C-20 ), 98.7 (C-30 ), 149.5 (C-40 ), 141.4 (C-50 ), 114.5 (C-60 ), 6.9 (6-CH3), 56.9 (20 -OMe), 56.6 (40 -OMe); HRESIMS m/z: 347.1109 [M þ H]þ (calcd. 347.1130 for C18H19O7). 4. Chemotaxonomic significance Although several flavanones and stilbenes have been previously isolated from Cyperus species (Zhou and Yin, 2012; Morikawa et al., 2010), the present study is the first report for the isolation of a new C-methylflavanone 5,50 ,7-trihydroxy20 ,40 -dimethoxy-6-methylflavanone (1), together with a known flavanone eriodictyol (2) (Wagner et al., 1976), and two stilbenes piceatannol (3) and resveratrol (4) (Lee et al., 2010) from the C. stoloniferus rhizomes. In addition, the C-methylflavonoid skeleton was found for the first time from the Cyperaceae family. Piceatannol has been isolated in low yield from other Cyperus plants (Lee et al., 2008; Morikawa et al., 2010; Ito et al., 2012), however this compound was found as a main component (approx. 0.18% dry weight) in the rhizomes of C. stoloniferus. Thus compounds 1 and 3 might be considered as important chemotaxonomic markers of C. stoloniferus. Acknowledgments This work is supported by a grant from the Ministry of Science and Technology (NCCBDHUD/2011-2014) and from the Vietnam Academy of Science and Technology (VAST04.01/13-14). We thank the Institute of Chemistry (VAST) for the NMR measurements, and Dr. ML Bourguet-Kondracki (Musée National d’Histoire Naturelle, Paris, France) for providing HRMS experiment. References Ito, T., Endo, H., Oyama, M., Iinuma, M., 2012. Phytochem. Lett. 5, 267. Lee, H.S., Lee, B.W., Kim, M.R., Jun, J.G., 2010. Bull. Korean Chem. Soc. 31, 971. Lee, S.I., Choi, H., Jeon, H., Baek, N.I., Kim, S.H., Kim, H.J., Cho, C.H., Ahn, H.C., Yang, J.H., Chae, B.S., Lim, J.P., Eun, J.S., Kim, D.K., 2008. Kor. J. Pharmacogn. 39, 233. Morikawa, T., Xu, F., Matsuda, H., Yoshikawa, M., 2010. Chem. Pharm. Bull. 58, 1379. Mustafa, K., Perry, N.B., Weavers, R.T., 2005. Biochem. Syst. Ecol. 33, 1049. Nguyen, X.D., Vu, V.D., Vu, N.L., 1995. Vietnamese J. Pharmacol. 235, 4. Slade, D., Ferreira, D., Marais, J.P., 2005. Phytochem. 66, 2177. Tran, H.T., Tran, T.N.D., 2012. Vietnamese J. Pharmacol. 432, 38. Vo, V.C., 2004. Dictionary of Vietnamese Medicinal Plants. Medicine Publisher, Hanoi. Vu, V.D., Mai, T.T., 1994. Vietnamese J. Pharmacol. 223, 16. Wagner, H., Chari, V.M., Sonnenbichlen, J., 1976. Tetrahedron Lett. 21, 1799. Zhou, Z., Yin, W., 2012. Molecules 17, 12636.
Contents lists available at SciVerse ScienceDirect
Biochemical Systematics and Ecology journal homepage: www.elsevier.com/locate/biochemsyseco
Flavanones and stilbenes from Cyperus stoloniferus Retz. Nguyen Minh Chau a, b, Tran Thi Hong Hanh a, Nguyen Thi Luyen a, Chau Van Minh a, Nguyen Tien Dat a, * a b
Institute of Marine Biochemistry, Vietnam Academy of Science and Technology, 18-Hoang Quoc Viet, Cau Giay, Hanoi, Viet Nam School of Chemical Engineering, Hanoi University of Science and Technology, 1-Dai Co Viet Road, Hanoi, Viet Nam
a r t i c l e i n f o Article history: Received 13 January 2013 Accepted 13 April 2013 Available online 15 May 2013 Keywords: Cyperus stoloniferus Cyperaceae C-methylflavonoid Stilbene Piceatannol
1. Subject and source Cyperus stoloniferus Retz. (Cyperaceae) widely grows in the coastal zones in Vietnam and has been used for treatment of menstrual disorders, dysmenorrhoea, stomachache, and inflammation (Vo, 2004). The rhizomes of C. stoloniferus were collected in Tien Hai, Thai Binh on June, 2011 and identified by Prof. Tran Huy Thai, Institute of Ecology and Biological Resources (IEBR), Vietnam Academy of Science and Technology (VAST). Voucher specimens have been deposited at the herbarium of the IEBR. 2. Previous work Although C. stoloniferus has shown similar pharmacological effects with C. rotundus in Vietnamese folk medicine (Vo, 2004), there are very few reports on the chemical composition and biological activity of this plant. Only three studies on the essential oil composition (Tran and Tran, 2012; Nguyen et al., 1995) and the analgesic activity (Vu and Mai, 1994) of C. stoloniferus were reported so far. 3. Present study The air-dried and powdered materials (2.5 kg) were extracted with methanol (6 L 3 times) in a sonic bath for 30 min. The combined extracts were concentrated under a vacuum to obtain a crude residue (210 g), which was then resuspended in water (1 L), and successively extracted by chloroform and ethyl acetate (each 1 L 3 times). The organic layers were
* Corresponding author. Tel.: þ84 4 37917049; fax: þ84 4 37917054. E-mail addresses: [email protected], [email protected] (N.T. Dat). 0305-1978/$ – see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.bse.2013.04.004
N.M. Chau et al. / Biochemical Systematics and Ecology 50 (2013) 220–222
221
concentrated to give 80.1 g and 47.7 g of chloroform and ethyl acetate residues, respectively. The chloroform residue was chromatographed on a silica gel column eluted by a gradient of 1–100% acetone in hexane to afford five fractions C1-5. Compound 1 (8.0 mg) was purified from C4 by a C18 column using a mobile phase of acetone-water (1:1 v/v). The ethyl acetate residue was chromatographed on a silica gel column eluted by a gradient of 1–100% methanol in chloroform to afford three fractions E1-3. The E1 was passed through a silica gel column eluted by hexane-chloroform-methanol (1:2:0.3 v/v) to obtain 4 (5.7 mg). A silica gel column chromatography of the fraction E2 using chloroform-methanol (20:1 v/v) as eluant afforded three subfractions E2a-c. Compound 2 (9.8 mg) was purified from E2a by a Sephadex LH-20 column eluted by a mobile phase of methanol-water (1:1 v/v). Compound 3 (4.5 g) was obtained by recrystallization in methanol from E2b. Compound 1 was obtained as a yellow solid. Its HRESIMS revealed the peak at m/z 347.1109 [M þ H]þ corresponding to the molecular formula C18H19O7. The 1H-NMR spectrum of 1 showed three aromatic singlets at dH 5.97 (1H, s, H-8), 6.69 (1H, s, H30 ) and 7.00 (1H, s, H-60 ), methine-methylene coupled protons at dH 5.62 (1H, dd, J ¼ 3.0, 13.0 Hz, H-2), 2.70 (1H, dd, J ¼ 3.0, 17.0 Hz, Ha-3) and 2.95 (1H, dd, J ¼ 13.0, 17.0 Hz, Hb-3). In addition, two methoxy and a C-methyl singlets were observed at dH 3.83 (3H, br s, 20 -OMe), 3.90 (3H, br s, 40 -OMe) and 1.97 (3H, br s, 6-Me). The 13C-NMR and DEPT spectra of 1 indicated the presence of three CH3, a CH2, four CH and ten quaternary carbon signals. The flavanone skeleton of 1 was recognized by the signals of a carbonyl group (dC 198.0, C-4), an oxymethine (dC 75.2, C-2) and a methylene (dC 43.4, C-3). The HMBC correlations (Fig. 1) from H-8 (dH 5.97) to dC 105.3 (C-6), 166.1 (C-7), 162.6 (C-9), and 103.0 (C-10), and from the methyl signal (dH 1.97) to dC 162.6 (C-5), 105.3 (C-6), and 166.1 (C-7) confirmed that the methyl group was located at C-6 in the A-ring. For the B-ring, two aromatic protons at dH 6.69 and 7.00 were all observed as singlets and showed any HMBC correlation each other indicating that they were located in para positions, i.e. H-30 and H-60 . The NOESY cross peaks between both methoxy signals and H-30 (dH 6.69) (Fig. 1) indicated that these two methoxy groups attached to C-20 and C-40 . The HMBC couplings from H-2 (dH 5.62) to C10 (dC 120.5) and C-20 (dC 151.5), and from H-60 (dH 7.00) to C-2 (dC 75.2), C-10 (dC 120.5), and C-20 (dC 151.5) allowed the NMR assignments of the B-ring. The negative optical rotation of 1 and a negative Cotton effects effect at 295 nm indicated the Sconfiguration at C-2 (Mustafa et al., 2005; Slade et al., 2005). Accordingly, compound 1 was newly elucidated to be (S)-5,50 ,7trihydroxy-20 ,40 -dimethoxy-6-methylflavanone. 3.1. (S)-5,50 ,7-trihydroxy-20 ,40 -dimethoxy-6-methylflavanone (1) 3 Yellow powder, ½a 25 M, MeOH) lmax(Dε) nm 295 (13.7), 345 (þ2.1); UV (MeOH) D ¼ –88.0 (c 0.1, MeOH); CD (c 1.4 10 lmax (log ε) 232 (3.35), 290 (3.44) nm; IR nmax(KBr): 3393, 1637, 1516, 1303, 1158 cm-1; 1H NMR (500 MHz, CD3OD): d 5.62 (1H, dd, J ¼ 3.0, 13.0 Hz, H-2), 2.70 (1H, dd, J ¼ 3.0, 17.0 Hz, H-3a), 2.95 (1H, dd, J ¼ 13.0, 17.0 Hz, H-3b), 5.97 (1H, s, H-8), 6.69 (1H, s, H-30 ), 7.00 (1H, s, H-60 ), 1.97 (3H, s, CH3), 3.83 (3H, s, 20 -OCH3), 3.90 (3H, s, 40 -OCH3); 13C NMR (125 MHz, CD3OD): d 75.2 (C-2),
Fig. 1. The structures of compounds 1–4 and key HMBC (/) and NOESY (4) correlations of 1.
222
N.M. Chau et al. / Biochemical Systematics and Ecology 50 (2013) 220–222
43.4 (C-3), 198.0 (C-4), 162.6 (C-5), 105.3 (C-6), 166.1 (C-7), 95.2 (C-8), 162.6 (C-9), 103.0 (C-10), 120.5 (C-10 ), 151.2 (C-20 ), 98.7 (C-30 ), 149.5 (C-40 ), 141.4 (C-50 ), 114.5 (C-60 ), 6.9 (6-CH3), 56.9 (20 -OMe), 56.6 (40 -OMe); HRESIMS m/z: 347.1109 [M þ H]þ (calcd. 347.1130 for C18H19O7). 4. Chemotaxonomic significance Although several flavanones and stilbenes have been previously isolated from Cyperus species (Zhou and Yin, 2012; Morikawa et al., 2010), the present study is the first report for the isolation of a new C-methylflavanone 5,50 ,7-trihydroxy20 ,40 -dimethoxy-6-methylflavanone (1), together with a known flavanone eriodictyol (2) (Wagner et al., 1976), and two stilbenes piceatannol (3) and resveratrol (4) (Lee et al., 2010) from the C. stoloniferus rhizomes. In addition, the C-methylflavonoid skeleton was found for the first time from the Cyperaceae family. Piceatannol has been isolated in low yield from other Cyperus plants (Lee et al., 2008; Morikawa et al., 2010; Ito et al., 2012), however this compound was found as a main component (approx. 0.18% dry weight) in the rhizomes of C. stoloniferus. Thus compounds 1 and 3 might be considered as important chemotaxonomic markers of C. stoloniferus. Acknowledgments This work is supported by a grant from the Ministry of Science and Technology (NCCBDHUD/2011-2014) and from the Vietnam Academy of Science and Technology (VAST04.01/13-14). We thank the Institute of Chemistry (VAST) for the NMR measurements, and Dr. ML Bourguet-Kondracki (Musée National d’Histoire Naturelle, Paris, France) for providing HRMS experiment. References Ito, T., Endo, H., Oyama, M., Iinuma, M., 2012. Phytochem. Lett. 5, 267. Lee, H.S., Lee, B.W., Kim, M.R., Jun, J.G., 2010. Bull. Korean Chem. Soc. 31, 971. Lee, S.I., Choi, H., Jeon, H., Baek, N.I., Kim, S.H., Kim, H.J., Cho, C.H., Ahn, H.C., Yang, J.H., Chae, B.S., Lim, J.P., Eun, J.S., Kim, D.K., 2008. Kor. J. Pharmacogn. 39, 233. Morikawa, T., Xu, F., Matsuda, H., Yoshikawa, M., 2010. Chem. Pharm. Bull. 58, 1379. Mustafa, K., Perry, N.B., Weavers, R.T., 2005. Biochem. Syst. Ecol. 33, 1049. Nguyen, X.D., Vu, V.D., Vu, N.L., 1995. Vietnamese J. Pharmacol. 235, 4. Slade, D., Ferreira, D., Marais, J.P., 2005. Phytochem. 66, 2177. Tran, H.T., Tran, T.N.D., 2012. Vietnamese J. Pharmacol. 432, 38. Vo, V.C., 2004. Dictionary of Vietnamese Medicinal Plants. Medicine Publisher, Hanoi. Vu, V.D., Mai, T.T., 1994. Vietnamese J. Pharmacol. 223, 16. Wagner, H., Chari, V.M., Sonnenbichlen, J., 1976. Tetrahedron Lett. 21, 1799. Zhou, Z., Yin, W., 2012. Molecules 17, 12636.