Subscribe to RSS
Acylated triterpene saponins from Atroxima liberica Stapf
The genus Atroxima (Polygalaceae), represented by trees, shrubs, herbs, or lianas (rarely) comprises 6 species distributed in the forests of Western and Central Africa . We previously reported the isolation and structural elucidation of seven pairs of preatroxigenin [(2β,3β,4α,22β)-2,3,22,27-tetrahydroxyolean-12-ene-23,28-dioic acid] glycosides called atroximasaponins A1/A2-G1/G2 from roots of A. congolana [2,3]. However, there is no previous study on A. liberica. In the course of our studies on the saponins of the Polygalaceae family to find the chimiotaxonomic markers, we have investigated the saponin fraction of the roots of A. liberica. We report here the isolation and identification of eight new acylated triterpene saponins (1–8) isolated as pairs of epimers named libericosides A1/A2– D1/D2, one pair of epimer the (Z)-epimer being new: libericoside E (9), one new sucrose ester: atroximoside (10), and six known compounds have been isolated from the roots of Atroxima liberica by repeated MPLC over silica gel. Their structures were elucidated on the basis of extensive 1D and 2D NMR spectroscopic studies and mass spectrometry. The new saponins (1 - 9) were evaluated for their cytotoxicity against HCT 116 and HT-29 human colon cancer cells, respectively.
Acknowledgements: The authors are grateful to the Conseil Régional de Bourgogne, France for financial support.
References: 1. Bila, B. et al. (1982) Bull. Soc. Chim. Belg. 91: 321–331.
2. Elbandy, M. et al. (2003)J. Nat. Prod. 66: 1154–1158.
3. Elbandy, M. et al. (2003) Helv. Chim. Acta 86: 522–531.