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Isolation of mimengoside B, a triterpenoid saponin from Buddleja madagascariensis
Journal of ETHNOPHARMACOLOGY ELSEVIER
Journal of Ethnopharmacology58 (1997) 215- 217
Short communication
Isolation of mimengoside B, a triterpenoid saponin from
Buddleja madagascariensis A . M . E m a m ~,c, A . M . M o u s s a ~, R . F a u r e
b
R . E l i a s c'*, G . B a l a n s a r d c
a Department of Biochemistry, Faculty of Agrieulture, Cairo University, Fayoum, Egypt b URA 1411l, University Aix-Marseille HI, Avenue Escadrille Normandie Niemen 13397, Marseille, cedex 13, France Laboratoire de Pharrnacognosie, Facultd de Pharmaeie, 27 Boulevard Jean Moulin 13385, Marseille, Cedex 5, France
Received 1 November 1995: accepted 18 October 1996
Abstract
The leaves of Buddleja madagascariensis are traditionally used to treat asthma, coughs and bronchitis. In this report we describe, for the first time, the identification of mimengoside B, a triterpenoid saponin, in the leaves of this plant. © 1997 Elsevier Science Ireland Ltd. Keywords: Buddleja madagascariensis; Mimengoside B; Therapeutic properties
1. Introduction Buddleja madagascariensis Lamk. (Buddlejaceae) is a wild shrub indigenous to Madagascar, but cultivated and naturalised in many tropical and subtropical regions. The leaves have been traditionally used as a remedy for asthma, coughs and bronchitis and as a soap substitute (Houghton, 1984). The presence of n-alkane mixture, sitosterol, stigmasterol and amyrin in the leaves of this plant have been described (Kapoor et al., 1981). Recently we identified two iridoids, aucuboside and methoxy catalpol, in the leaves
* Corresponding author
(Emam et al., 1995). In the present communication we report the isolation and structure elucidation of a triterpenoid saponin, mimengoside B which has been described for the first time in this plant.
2. Materials and methods 2.1. Plant m a t e r i a l
Leaves were collected in Fayoum, Egypt, in May 1994 and identified by the Taxonomic Department, Faculty of Science, Cairo University. A voucher specimen was deposited in the Herbarium of the Department of Biochemistry (no. B.M. 1), Faculty of Agriculture, Fayoum, Cairo University.
0378-8741/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved. PI! S0378-8741 (97)00095-0
216
A.M. Emam et al. /Journal of Ethnopharmacology 58 (1997) 215 217
2.2. Extraction and isolation Dried powdered leaves (1 kg) were extracted with methanol (MeOH; 10 1) at room temperature. The MeOH extract was concentrated and freeze dried to yield 200 g (20%). Ten grammes of this extract was fractionated on a silica gel column (I kg; Merck 230-400 mesh) and eluted with a mixture of CHC13:MeOH:H20 (70:30:5); 13 fractions (each 750 ml) were collected. Fraction no. 6 (1 g) was further purified on reversed phase RP-18 Column (JobinYvon) using HzO:MeOH as eluent (90:10 ~ 100% MeOH, 500 ml) to yield 115 mg (0.23%) of pure compound (20:80; between 0-250 ml).
2.3. Identification of the compound The isolated compound was characterised by spectroscopic studies (1H and 13C NMR and FABMS). The FAB-MS spectrum was obtained on a Nermag R10-10H mass spectrometer in the negative ion mode in thioglycerol matrix. NMR spectra were recorded on a Bruker AMX-400 spectrometer at 400 MHz for ~H and 100 MHz for '3C in CD3OD solution using TMS as an internal standard.
2.4. Analytical TLC TLC analysis of the compound was performed on precoated Si gel plates (F254, 0.25 mm, Merck)
._
HI~Q(~ ) HO OH
using the following system: (a) n-BuOH:AcOH:H20 (4:1:5); (b) CHC13:MeOH:H20 (70: 30: 5) for saponin and (c) CH2Clz:MeOH:H20 (50:25:5) for sugars. Detection: for saponin H z S O 4 followed by heating; for sugars naphtoresorcinol phosphoric acid followed by heating. 3. Results and discussions
The methanol extract of the leaves of Buddleja madagascariensis upon silica gel and reversed phase RP-18 column chromatography led to the isolation of one constituent, which gave a positive reaction when tested with Libermann-Burchard reagent. Acidic hydrolysis of the saponin afforded fucose, glucose and rhamnose in the ratio 1:2:1 as the sugar moiety. The compound was not affected by alkaline treatment suggesting that it was a monodesmosidic saponin. The FAB-MS spectrum showed a quasi ion peak due to [M-H] at m/z 1103 indicating a Mw of 1104 (C55H92022).The signals at m/z 957 ([(M-H)- 146] ), 795 ([(M-H)-308]), 633 ([(M-H)-470]), and 487 ([(M-H)-616]-) correspond to subsequent losses of four glycosyl moities. The ~3CNMR exhibited a 55 carbon signal, made up of one double bond (6 122.8, 150.5 ppm), two hydroxyl methyls (6 64.6, 69.7 ppm) one oxygenated methine (6 84.3 ppm) methoxy group (6 53.3 ppm),
x,,."
OH HO OH
A.M. Emam et al. /Journal q] Ethnopharmacology 58 (1997) 215 217
six methyls, nine methylenes and seven quaternary carbons in the aglycone moiety and four anomeric carbons (d 103.4, 105.1,104.6 and 102.8 ppm) and two methyls (d 16.8, 17.8 ppm) in the sugar moiety. The presence of a glycosylation shift at C-2', C-3' (/i 76.7, 85.6 ppm) of fucose and at C-4' (d 78.3 ppm) of glc' suggested the sugar linkages at these positions. From these results the structure of saponin was identified as 3-O-:~-L-rhamnopyranosyl-(1 --* 4)-flD- glucopyranosyl - (1 --* 3) - [fl- D- glucopyranosyl(1 --* 2)-fl-D-fucopyranoside]-3,23,28-trihydroxyll-methoxy-olean-12-ene (mimengoside B); [:~]~ + 1.5 (MeOH) RF = 0.35 (system a), 0.28 (system b) previously isolated from Buddleja flos (NingDing et al., 1992).
217
Western medicine, and the presence of mimengoside B in Buddleja might account for this activity. This is the first report of mimengoside B in the Buddleja madagascariensis and allowed us to correlate the activity of the substance with the therapeutic properties described for this plant.
Acknowledgements We wish to thank G. Boudon for technical collaboration.
References 4. Conclusion An infusion of the leaves of Buddleja madagascariensis is drunk to treat asthma, coughs and bronchitis. This is probably due to an expectorant action caused by stimulation of secretion in the respiratory tract. It is known that several terpene and saponins have this effect, e.g. the use of turpentine oil in proprietary cough remedies in
Emam, A.M., Moussa, A.M., Faure, R., Debrauwer, L., Elias, R., Balansard, G., 1995. lridoids from Buddleja madagascariensis Lam.. Pharm. Pharmacol. Lett. 5, 103 104. Houghton, P.J., 1984. Ethnopharmacology of some Buddleja species. J. Ethnopharmacol. 11, 293 308. Kapoor, V.K., Chawla, A.S., Gupta, Y.C., Passannanti, S., Paternostro, M.P., 1981. Constituents of Buddleia species leaves. Fitoterapia 52, 235-237. NingDing, Yahara, S., Nohara, T., 1992. Structure of mimengosides A and B. new triterpenoid glycosides from Buddleja flos produced in China. Chem. Pharm. Bull. 40, 780-782.
Journal of Ethnopharmacology58 (1997) 215- 217
Short communication
Isolation of mimengoside B, a triterpenoid saponin from
Buddleja madagascariensis A . M . E m a m ~,c, A . M . M o u s s a ~, R . F a u r e
b
R . E l i a s c'*, G . B a l a n s a r d c
a Department of Biochemistry, Faculty of Agrieulture, Cairo University, Fayoum, Egypt b URA 1411l, University Aix-Marseille HI, Avenue Escadrille Normandie Niemen 13397, Marseille, cedex 13, France Laboratoire de Pharrnacognosie, Facultd de Pharmaeie, 27 Boulevard Jean Moulin 13385, Marseille, Cedex 5, France
Received 1 November 1995: accepted 18 October 1996
Abstract
The leaves of Buddleja madagascariensis are traditionally used to treat asthma, coughs and bronchitis. In this report we describe, for the first time, the identification of mimengoside B, a triterpenoid saponin, in the leaves of this plant. © 1997 Elsevier Science Ireland Ltd. Keywords: Buddleja madagascariensis; Mimengoside B; Therapeutic properties
1. Introduction Buddleja madagascariensis Lamk. (Buddlejaceae) is a wild shrub indigenous to Madagascar, but cultivated and naturalised in many tropical and subtropical regions. The leaves have been traditionally used as a remedy for asthma, coughs and bronchitis and as a soap substitute (Houghton, 1984). The presence of n-alkane mixture, sitosterol, stigmasterol and amyrin in the leaves of this plant have been described (Kapoor et al., 1981). Recently we identified two iridoids, aucuboside and methoxy catalpol, in the leaves
* Corresponding author
(Emam et al., 1995). In the present communication we report the isolation and structure elucidation of a triterpenoid saponin, mimengoside B which has been described for the first time in this plant.
2. Materials and methods 2.1. Plant m a t e r i a l
Leaves were collected in Fayoum, Egypt, in May 1994 and identified by the Taxonomic Department, Faculty of Science, Cairo University. A voucher specimen was deposited in the Herbarium of the Department of Biochemistry (no. B.M. 1), Faculty of Agriculture, Fayoum, Cairo University.
0378-8741/97/$17.00 © 1997 Elsevier Science Ireland Ltd. All rights reserved. PI! S0378-8741 (97)00095-0
216
A.M. Emam et al. /Journal of Ethnopharmacology 58 (1997) 215 217
2.2. Extraction and isolation Dried powdered leaves (1 kg) were extracted with methanol (MeOH; 10 1) at room temperature. The MeOH extract was concentrated and freeze dried to yield 200 g (20%). Ten grammes of this extract was fractionated on a silica gel column (I kg; Merck 230-400 mesh) and eluted with a mixture of CHC13:MeOH:H20 (70:30:5); 13 fractions (each 750 ml) were collected. Fraction no. 6 (1 g) was further purified on reversed phase RP-18 Column (JobinYvon) using HzO:MeOH as eluent (90:10 ~ 100% MeOH, 500 ml) to yield 115 mg (0.23%) of pure compound (20:80; between 0-250 ml).
2.3. Identification of the compound The isolated compound was characterised by spectroscopic studies (1H and 13C NMR and FABMS). The FAB-MS spectrum was obtained on a Nermag R10-10H mass spectrometer in the negative ion mode in thioglycerol matrix. NMR spectra were recorded on a Bruker AMX-400 spectrometer at 400 MHz for ~H and 100 MHz for '3C in CD3OD solution using TMS as an internal standard.
2.4. Analytical TLC TLC analysis of the compound was performed on precoated Si gel plates (F254, 0.25 mm, Merck)
._
HI~Q(~ ) HO OH
using the following system: (a) n-BuOH:AcOH:H20 (4:1:5); (b) CHC13:MeOH:H20 (70: 30: 5) for saponin and (c) CH2Clz:MeOH:H20 (50:25:5) for sugars. Detection: for saponin H z S O 4 followed by heating; for sugars naphtoresorcinol phosphoric acid followed by heating. 3. Results and discussions
The methanol extract of the leaves of Buddleja madagascariensis upon silica gel and reversed phase RP-18 column chromatography led to the isolation of one constituent, which gave a positive reaction when tested with Libermann-Burchard reagent. Acidic hydrolysis of the saponin afforded fucose, glucose and rhamnose in the ratio 1:2:1 as the sugar moiety. The compound was not affected by alkaline treatment suggesting that it was a monodesmosidic saponin. The FAB-MS spectrum showed a quasi ion peak due to [M-H] at m/z 1103 indicating a Mw of 1104 (C55H92022).The signals at m/z 957 ([(M-H)- 146] ), 795 ([(M-H)-308]), 633 ([(M-H)-470]), and 487 ([(M-H)-616]-) correspond to subsequent losses of four glycosyl moities. The ~3CNMR exhibited a 55 carbon signal, made up of one double bond (6 122.8, 150.5 ppm), two hydroxyl methyls (6 64.6, 69.7 ppm) one oxygenated methine (6 84.3 ppm) methoxy group (6 53.3 ppm),
x,,."
OH HO OH
A.M. Emam et al. /Journal q] Ethnopharmacology 58 (1997) 215 217
six methyls, nine methylenes and seven quaternary carbons in the aglycone moiety and four anomeric carbons (d 103.4, 105.1,104.6 and 102.8 ppm) and two methyls (d 16.8, 17.8 ppm) in the sugar moiety. The presence of a glycosylation shift at C-2', C-3' (/i 76.7, 85.6 ppm) of fucose and at C-4' (d 78.3 ppm) of glc' suggested the sugar linkages at these positions. From these results the structure of saponin was identified as 3-O-:~-L-rhamnopyranosyl-(1 --* 4)-flD- glucopyranosyl - (1 --* 3) - [fl- D- glucopyranosyl(1 --* 2)-fl-D-fucopyranoside]-3,23,28-trihydroxyll-methoxy-olean-12-ene (mimengoside B); [:~]~ + 1.5 (MeOH) RF = 0.35 (system a), 0.28 (system b) previously isolated from Buddleja flos (NingDing et al., 1992).
217
Western medicine, and the presence of mimengoside B in Buddleja might account for this activity. This is the first report of mimengoside B in the Buddleja madagascariensis and allowed us to correlate the activity of the substance with the therapeutic properties described for this plant.
Acknowledgements We wish to thank G. Boudon for technical collaboration.
References 4. Conclusion An infusion of the leaves of Buddleja madagascariensis is drunk to treat asthma, coughs and bronchitis. This is probably due to an expectorant action caused by stimulation of secretion in the respiratory tract. It is known that several terpene and saponins have this effect, e.g. the use of turpentine oil in proprietary cough remedies in
Emam, A.M., Moussa, A.M., Faure, R., Debrauwer, L., Elias, R., Balansard, G., 1995. lridoids from Buddleja madagascariensis Lam.. Pharm. Pharmacol. Lett. 5, 103 104. Houghton, P.J., 1984. Ethnopharmacology of some Buddleja species. J. Ethnopharmacol. 11, 293 308. Kapoor, V.K., Chawla, A.S., Gupta, Y.C., Passannanti, S., Paternostro, M.P., 1981. Constituents of Buddleia species leaves. Fitoterapia 52, 235-237. NingDing, Yahara, S., Nohara, T., 1992. Structure of mimengosides A and B. new triterpenoid glycosides from Buddleja flos produced in China. Chem. Pharm. Bull. 40, 780-782.