- Email: [email protected]
Sesquiterpene lactones from Centaurea tougourensis
Biochemical Systematics and Ecology 43 (2012) 163–165
Contents lists available at SciVerse ScienceDirect
Biochemical Systematics and Ecology journal homepage: www.elsevier.com/locate/biochemsyseco
Sesquiterpene lactones from Centaurea tougourensis Amar Nacer a, *, Joumaa Merza b, Zahia Kabouche c, Salah Rhouati a, Joel Boustie d, Pascal Richomme b a
Laboratoire de Produits d’Origine Végétale et Synthèse Organique, Faculté des Sciences Exactes, Université Mentouri Constantine, Algeria Substances d’Origine Naturelle et Analogues Structuraux, IFR 149, UFR des Sciences Pharmaceutiques, Université d’Angers, France c Laboratoires d’Obtention de Substances Thérapeutiques, Faculté des Sciences Exactes, Université Mentouri Constantine, Algeria d Produits Naturels, Synthèses et Chimie Médicinale, UMR 6226, Faculté des Sciences pharmaceutique et biologiques, Université de Rennes 1, France b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 2 December 2010 Accepted 20 August 2011 Available online 21 April 2012
Fractionation of the dichloromethane extract of Centaurea tougourensis (Boiss. and Reut.) led to the isolation of four sesquiterpene lactones: an elemanolide (1), a germacranolide (2) and two heliangolides (3, 4), the latter being identified for the first time from natural source. Ó 2011 Elsevier Ltd. All rights reserved.
Keywords: Centaurea tougourensis Asteraceae Sesquiterpene lactones Heliangolides
1. Subject and source Centaurea tougourensis Boiss. & Reut. (Asteraceae) is an endemic species growing in Northeastern Algeria (Quezel and Santa, 1963) whose aqueous decoctions are used for their hypoglycemic properties. C. tougourensis was collected during flowering (April 2004) near Batna (North-eastern Algeria) then a voucher specimen (ref. MBang, 2006.1) was deposited at the Botanic Museum of Angers (France). The genus Centaurea is known to be a rich source of flavonoids (Flamini et al., 2001; Ribeiro et al., 2002), sesquiterpene lactones (Koukoulitsa et al., 2002; Skaltza et al., 2000; Vajs et al., 1999) and triterpenes (Oksuz and Serin, 1997). 2. Previous work Four methylated flavones and two flavonoid aglycones (jaceosidin, eupatilin, nepetin, 30 -O-methyleupatorin, apigenin and kaempferol) have previously been isolated from the aerial parts of C. tougourensis (Nacer et al., 2006). Several species of the genus Centaurea growing in Algeria have been the subject of chemical investigation and new sources of natural products have been found (Akkal et al., 1999; Benayache et al., 1992; Bentamene et al., 2005; Medjroubi et al., 1997). 3. Present study 3.1. Experimental The air dried powdered aerial parts of C. tougourensis (1 kg) were macerated at room temperature, in a methanol aqueous solution (80%). The extract was concentrated under reduced pressure, diluted and filtered to remove chlorophyll, * Corresponding author. Tel.: þ213 552072608. E-mail addresses: [email protected] (A. Nacer), [email protected] (Z. Kabouche), [email protected] (J. Boustie), pascal.richomme@ univ-angers.fr (P. Richomme). 0305-1978/$ – see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.bse.2011.08.013
164
A. Nacer et al. / Biochemical Systematics and Ecology 43 (2012) 163–165
and then successively extracted with petroleum ether, dichloromethane, ethyl acetate and n-butanol. The dichloromethane extract (5.9 g) was separated by column chromatography on silica gel (70–200 mesh), eluted with pentane, dichloromethane, dichloromethane/ethyl acetate [(8:2), (1:1), (2:8)], ethyl acetate and methanol to give fractions A (162 mg), B (1536 mg), C (1238 mg), and D (1343 mg). Fraction C was subjected to column chromatography on silica gel (60–200mesh) eluted by dichloromethane-methanol with increasing polarity. Thirteen fractions were collected. Fractions 10–12 (172 mg) were subjected to radial chromatography using an CHCl3/EtOAc (8:2) mixture then purified with normal phase HPLC using a silica gel diol-grafted column eluted with CHCl3/EtOAc (8:2) mixture to give compounds 1 (13.5 mg) and 2 (23 mg). Fractions 5 and 6 (243 mg) were subjected to radial chromatography using a mixture of diethyl ether/ dichloromethane/acetic acid (2: 1: 0.25) then purified with HPLC using a silica gel diol-grafted column, eluted with CHCl3/ AcOEt (8:2) mixture to obtain compounds 3 (33 mg) and 4 (21 mg). 3.2. Results and discussion All compounds were identified through CIMS and IR analysis as well as extensive NMR studies including 1H NMR, 13C NMR, DEPT, COSY, HMQC, HMBC and NOESY experiments. Each isolated compound exhibited the same ester moiety at C-8a. Compounds 1–4 were readily identified as 8a-(3,4-dihydroxy-2-methylene-butanoyloxy)- dehydromelitensin (1) (Skaltza et al., 2000), 8a-(3, 4-dihydroxy-2-methylene-butanoyl)- salonitenolide or cnicin (2) (Bruno et al., 2002), (6R, 7R, 8S, 30 R) 8a-(3, 4-dihydroxy-2-methylene-butanoyloxy)-15-acetoxy-helianga 1(10), 4(5), 11(13) trien-6-olide (3) (Cardona et al., 1994) and (6R, 7R, 8S, 30 R) 8a-(3, 4-dihydroxy-2-methylene-butanoyloxy)-15-oxo-helianga 1(10), 4(5), 11(13) trien-6-olide(4). It may be noticed that the structure of the elemanolide-type sesquiterpene lactone 1 results from a Cope rearrangement of cnicin (2) (Rosselli et al., 2003) whereas the 1H NMR and 13C NMR spectra of 4 were in total accordance with literature data (Rosselli et al., 2003), although Dr Rosselli has since indicated that in this paper it was incorrectly assigned a negative rotation (per. Commun.).
4. Chemotaxonomic significance The present phytochemical investigation resulted in the isolation of four sesquiterpene lactones bearing a 8a-(3, 4dihydroxy-2-methylene-butanoyloxy) side chain: two heliangolides (3, 4) as the major products, an elemanolide (1) and a germacranolide (cnicin, 2). 1 and 2 are often described in species of Centaurea (Karioti et al., 2002; Saroglou et al., 2005), whilst more than 60 species are reported to contain cnicin. It is suggested that C. tougourensis belongs to the section Acrolophus Cass. (Nowak et al., 1984), as 36 out of 39 taxa studied in this section contain cnicin (Gousiadou and Skaltsa, 2003). Additionally, the chemistry of the section is characterized by the absence of guaianolides, which are common metabolites in other species of Centaurea (Connolly and Hill, 1991; Fraga, 2000, 1999, 1998, 1997, 1996, 1995, 1994, 1993, 1992). 3 was only described once in Centaurea paui (Cardona et al., 1994), whereas 4, which can be hemisynthetized from cnicin (Rosselli et al., 2003), was isolated here for the first time from a natural source. Acknowledgments This work was financially supported by the M.E.S.R.S. and the F.N.R. The authors are grateful to Dr S. Sinbandhit (University Rennes1, France) for NMR recordings, and to Dr S. Rosselli (University of Palermo, Italy) for helpful discussions about heliangolides absolute configurations.
A. Nacer et al. / Biochemical Systematics and Ecology 43 (2012) 163–165
Appendix. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.bse.2011.08.013. References Akkal, S., Benayache, F., Benayache, S., Medjroubi, K., Jay, M., Tillequin, F., Seguin, E., 1999. Fitoterapia 70, 368. Bentamene, A., Benayache, S., Creche, J., Petit, G., Bermejo-Barrera, J., Leon, F., Benayache, F., 2005. Biochem. Syst. Ecol. 33, 1061. Benayache, F., Benayache, S., Medjroubi, K., Aclinou, P., Drozdz, B., Nowak, G., 1992. Phytochemistry 12, 4359. Bruno, M., Maggio, A., Rosselli, S., Gedris, T.E., Herz, W., 2002. Biochem. Syst. Ecol. 30, 379. Cardona, L., Garcia, B., Navarro, F.I., Pedro, J.R., 1994. Nat. Prod. Lett. 5, 47. Connolly, J.D., Hill, R.A., 1991. Dictionary of Terpenoids, vol. 1. Chapman and Hall, London. Flamini, G., Antognoli, E., Morelli, I., 2001. Phytochemistry 57, 459. Fraga, B.M., 1992. Natural sesquiterpenoids. Nat. Prod. Rep. 9 217and 577. Fraga, B.M., 1993. Natural sesquiterpenoids. Nat. Prod. Rep. 10, 397. Fraga, B.M., 1994. Natural sesquiterpenoids. Nat. Prod. Rep. 11, 533. Fraga, B.M., 1995. Natural sesquiterpenoids. Nat. Prod. Rep. 12, 303. Fraga, B.M., 1996. Natural sesquiterpenoids. Nat. Prod. Rep. 13, 307. Fraga, B.M., 1997. Natural sesquiterpenoids. Nat. Prod. Rep. 14, 145. Fraga, B.M., 1998. Natural sesquiterpenoids. Nat. Prod. Rep. 15, 73. Fraga, B.M., 1999. Natural sesquiterpenoids. Nat. Prod. Rep. 16 21and 711. Fraga, B.M., 2000. Natural sesquiterpenoids. Nat. Prod. Rep. 17, 483. Gousiadou, C., Skaltsa, H., 2003. Biochem. Syst. Ecol. 31, 389. Karioti, A., Skaltsa, H., Lazari, D., Sokovic, M., Garcia, B., Harvala, C., 2002. Z. Naturforsch. 57c, 75. Koukoulitsa, E., Skaltsa, H., Karioti, A., Demetzos, D.K., 2002. Planta Med. 68, 649. Medjroubi, K., Benayache, F., Benayache, S., Akkal, S., Khalfallah, N., Aclinou, P., 1997. Phytochemistry 45, 1449. Nacer, A., Boustie, J., Bernard, A., Touzani, R., Kabouche, Z., 2006. Chem. Nat. Compd 42, 230. Nowak, G., Drozdz, B., Georgiadis, T., 1984. Acta Soc. Bot. Pol 53, 199. Oksuz, S., Serin, S., 1997. Phytochemistry 46, 545. Quezel, P., Santa, S., 1963. Nouvelle Flore de l’Algérie et des Régions Désertiques et Méridionales, vol. 2 1023, C.N.R.S. Paris. Ribeiro, N.L., Nahar, L., Kumarasamy, Y., Mir-Babayev, N., Sarker, S.D., 2002. Biochem. Syst.Ecol 30, 1097. Rosselli, S., Maggio, A., Raccuglia, R.A., Bruno, M., 2003. Eur. J. Org. Chem. 14, 2690. Saroglou, V., Karioti, A., Demetzos, C., Dimas, K., Skaltsa, H., 2005. J. Nat. Prod. 68, 1404. Skaltza, H., Lazari, D., Panagouleas, C., Georgiadou, E., Garcia, B., Sokovic, M., 2000. Phytochemistry 55, 903. Vajs, V., Todorovic, N., Ristic, M., Tesevic, V., Todorovic, B., Janachovic, P., Marin, P., Milosavljevic, S., 1999. Phytochemistry 52, 383.
165
Contents lists available at SciVerse ScienceDirect
Biochemical Systematics and Ecology journal homepage: www.elsevier.com/locate/biochemsyseco
Sesquiterpene lactones from Centaurea tougourensis Amar Nacer a, *, Joumaa Merza b, Zahia Kabouche c, Salah Rhouati a, Joel Boustie d, Pascal Richomme b a
Laboratoire de Produits d’Origine Végétale et Synthèse Organique, Faculté des Sciences Exactes, Université Mentouri Constantine, Algeria Substances d’Origine Naturelle et Analogues Structuraux, IFR 149, UFR des Sciences Pharmaceutiques, Université d’Angers, France c Laboratoires d’Obtention de Substances Thérapeutiques, Faculté des Sciences Exactes, Université Mentouri Constantine, Algeria d Produits Naturels, Synthèses et Chimie Médicinale, UMR 6226, Faculté des Sciences pharmaceutique et biologiques, Université de Rennes 1, France b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 2 December 2010 Accepted 20 August 2011 Available online 21 April 2012
Fractionation of the dichloromethane extract of Centaurea tougourensis (Boiss. and Reut.) led to the isolation of four sesquiterpene lactones: an elemanolide (1), a germacranolide (2) and two heliangolides (3, 4), the latter being identified for the first time from natural source. Ó 2011 Elsevier Ltd. All rights reserved.
Keywords: Centaurea tougourensis Asteraceae Sesquiterpene lactones Heliangolides
1. Subject and source Centaurea tougourensis Boiss. & Reut. (Asteraceae) is an endemic species growing in Northeastern Algeria (Quezel and Santa, 1963) whose aqueous decoctions are used for their hypoglycemic properties. C. tougourensis was collected during flowering (April 2004) near Batna (North-eastern Algeria) then a voucher specimen (ref. MBang, 2006.1) was deposited at the Botanic Museum of Angers (France). The genus Centaurea is known to be a rich source of flavonoids (Flamini et al., 2001; Ribeiro et al., 2002), sesquiterpene lactones (Koukoulitsa et al., 2002; Skaltza et al., 2000; Vajs et al., 1999) and triterpenes (Oksuz and Serin, 1997). 2. Previous work Four methylated flavones and two flavonoid aglycones (jaceosidin, eupatilin, nepetin, 30 -O-methyleupatorin, apigenin and kaempferol) have previously been isolated from the aerial parts of C. tougourensis (Nacer et al., 2006). Several species of the genus Centaurea growing in Algeria have been the subject of chemical investigation and new sources of natural products have been found (Akkal et al., 1999; Benayache et al., 1992; Bentamene et al., 2005; Medjroubi et al., 1997). 3. Present study 3.1. Experimental The air dried powdered aerial parts of C. tougourensis (1 kg) were macerated at room temperature, in a methanol aqueous solution (80%). The extract was concentrated under reduced pressure, diluted and filtered to remove chlorophyll, * Corresponding author. Tel.: þ213 552072608. E-mail addresses: [email protected] (A. Nacer), [email protected] (Z. Kabouche), [email protected] (J. Boustie), pascal.richomme@ univ-angers.fr (P. Richomme). 0305-1978/$ – see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.bse.2011.08.013
164
A. Nacer et al. / Biochemical Systematics and Ecology 43 (2012) 163–165
and then successively extracted with petroleum ether, dichloromethane, ethyl acetate and n-butanol. The dichloromethane extract (5.9 g) was separated by column chromatography on silica gel (70–200 mesh), eluted with pentane, dichloromethane, dichloromethane/ethyl acetate [(8:2), (1:1), (2:8)], ethyl acetate and methanol to give fractions A (162 mg), B (1536 mg), C (1238 mg), and D (1343 mg). Fraction C was subjected to column chromatography on silica gel (60–200mesh) eluted by dichloromethane-methanol with increasing polarity. Thirteen fractions were collected. Fractions 10–12 (172 mg) were subjected to radial chromatography using an CHCl3/EtOAc (8:2) mixture then purified with normal phase HPLC using a silica gel diol-grafted column eluted with CHCl3/EtOAc (8:2) mixture to give compounds 1 (13.5 mg) and 2 (23 mg). Fractions 5 and 6 (243 mg) were subjected to radial chromatography using a mixture of diethyl ether/ dichloromethane/acetic acid (2: 1: 0.25) then purified with HPLC using a silica gel diol-grafted column, eluted with CHCl3/ AcOEt (8:2) mixture to obtain compounds 3 (33 mg) and 4 (21 mg). 3.2. Results and discussion All compounds were identified through CIMS and IR analysis as well as extensive NMR studies including 1H NMR, 13C NMR, DEPT, COSY, HMQC, HMBC and NOESY experiments. Each isolated compound exhibited the same ester moiety at C-8a. Compounds 1–4 were readily identified as 8a-(3,4-dihydroxy-2-methylene-butanoyloxy)- dehydromelitensin (1) (Skaltza et al., 2000), 8a-(3, 4-dihydroxy-2-methylene-butanoyl)- salonitenolide or cnicin (2) (Bruno et al., 2002), (6R, 7R, 8S, 30 R) 8a-(3, 4-dihydroxy-2-methylene-butanoyloxy)-15-acetoxy-helianga 1(10), 4(5), 11(13) trien-6-olide (3) (Cardona et al., 1994) and (6R, 7R, 8S, 30 R) 8a-(3, 4-dihydroxy-2-methylene-butanoyloxy)-15-oxo-helianga 1(10), 4(5), 11(13) trien-6-olide(4). It may be noticed that the structure of the elemanolide-type sesquiterpene lactone 1 results from a Cope rearrangement of cnicin (2) (Rosselli et al., 2003) whereas the 1H NMR and 13C NMR spectra of 4 were in total accordance with literature data (Rosselli et al., 2003), although Dr Rosselli has since indicated that in this paper it was incorrectly assigned a negative rotation (per. Commun.).
4. Chemotaxonomic significance The present phytochemical investigation resulted in the isolation of four sesquiterpene lactones bearing a 8a-(3, 4dihydroxy-2-methylene-butanoyloxy) side chain: two heliangolides (3, 4) as the major products, an elemanolide (1) and a germacranolide (cnicin, 2). 1 and 2 are often described in species of Centaurea (Karioti et al., 2002; Saroglou et al., 2005), whilst more than 60 species are reported to contain cnicin. It is suggested that C. tougourensis belongs to the section Acrolophus Cass. (Nowak et al., 1984), as 36 out of 39 taxa studied in this section contain cnicin (Gousiadou and Skaltsa, 2003). Additionally, the chemistry of the section is characterized by the absence of guaianolides, which are common metabolites in other species of Centaurea (Connolly and Hill, 1991; Fraga, 2000, 1999, 1998, 1997, 1996, 1995, 1994, 1993, 1992). 3 was only described once in Centaurea paui (Cardona et al., 1994), whereas 4, which can be hemisynthetized from cnicin (Rosselli et al., 2003), was isolated here for the first time from a natural source. Acknowledgments This work was financially supported by the M.E.S.R.S. and the F.N.R. The authors are grateful to Dr S. Sinbandhit (University Rennes1, France) for NMR recordings, and to Dr S. Rosselli (University of Palermo, Italy) for helpful discussions about heliangolides absolute configurations.
A. Nacer et al. / Biochemical Systematics and Ecology 43 (2012) 163–165
Appendix. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.bse.2011.08.013. References Akkal, S., Benayache, F., Benayache, S., Medjroubi, K., Jay, M., Tillequin, F., Seguin, E., 1999. Fitoterapia 70, 368. Bentamene, A., Benayache, S., Creche, J., Petit, G., Bermejo-Barrera, J., Leon, F., Benayache, F., 2005. Biochem. Syst. Ecol. 33, 1061. Benayache, F., Benayache, S., Medjroubi, K., Aclinou, P., Drozdz, B., Nowak, G., 1992. Phytochemistry 12, 4359. Bruno, M., Maggio, A., Rosselli, S., Gedris, T.E., Herz, W., 2002. Biochem. Syst. Ecol. 30, 379. Cardona, L., Garcia, B., Navarro, F.I., Pedro, J.R., 1994. Nat. Prod. Lett. 5, 47. Connolly, J.D., Hill, R.A., 1991. Dictionary of Terpenoids, vol. 1. Chapman and Hall, London. Flamini, G., Antognoli, E., Morelli, I., 2001. Phytochemistry 57, 459. Fraga, B.M., 1992. Natural sesquiterpenoids. Nat. Prod. Rep. 9 217and 577. Fraga, B.M., 1993. Natural sesquiterpenoids. Nat. Prod. Rep. 10, 397. Fraga, B.M., 1994. Natural sesquiterpenoids. Nat. Prod. Rep. 11, 533. Fraga, B.M., 1995. Natural sesquiterpenoids. Nat. Prod. Rep. 12, 303. Fraga, B.M., 1996. Natural sesquiterpenoids. Nat. Prod. Rep. 13, 307. Fraga, B.M., 1997. Natural sesquiterpenoids. Nat. Prod. Rep. 14, 145. Fraga, B.M., 1998. Natural sesquiterpenoids. Nat. Prod. Rep. 15, 73. Fraga, B.M., 1999. Natural sesquiterpenoids. Nat. Prod. Rep. 16 21and 711. Fraga, B.M., 2000. Natural sesquiterpenoids. Nat. Prod. Rep. 17, 483. Gousiadou, C., Skaltsa, H., 2003. Biochem. Syst. Ecol. 31, 389. Karioti, A., Skaltsa, H., Lazari, D., Sokovic, M., Garcia, B., Harvala, C., 2002. Z. Naturforsch. 57c, 75. Koukoulitsa, E., Skaltsa, H., Karioti, A., Demetzos, D.K., 2002. Planta Med. 68, 649. Medjroubi, K., Benayache, F., Benayache, S., Akkal, S., Khalfallah, N., Aclinou, P., 1997. Phytochemistry 45, 1449. Nacer, A., Boustie, J., Bernard, A., Touzani, R., Kabouche, Z., 2006. Chem. Nat. Compd 42, 230. Nowak, G., Drozdz, B., Georgiadis, T., 1984. Acta Soc. Bot. Pol 53, 199. Oksuz, S., Serin, S., 1997. Phytochemistry 46, 545. Quezel, P., Santa, S., 1963. Nouvelle Flore de l’Algérie et des Régions Désertiques et Méridionales, vol. 2 1023, C.N.R.S. Paris. Ribeiro, N.L., Nahar, L., Kumarasamy, Y., Mir-Babayev, N., Sarker, S.D., 2002. Biochem. Syst.Ecol 30, 1097. Rosselli, S., Maggio, A., Raccuglia, R.A., Bruno, M., 2003. Eur. J. Org. Chem. 14, 2690. Saroglou, V., Karioti, A., Demetzos, C., Dimas, K., Skaltsa, H., 2005. J. Nat. Prod. 68, 1404. Skaltza, H., Lazari, D., Panagouleas, C., Georgiadou, E., Garcia, B., Sokovic, M., 2000. Phytochemistry 55, 903. Vajs, V., Todorovic, N., Ristic, M., Tesevic, V., Todorovic, B., Janachovic, P., Marin, P., Milosavljevic, S., 1999. Phytochemistry 52, 383.
165