Nebulosides A-B, novel triterpene saponins from under-ground parts of Gypsophila arrostii Guss. var. nebulosa

Abstract

A bioassay-guided phytochemical analysis of the triterpene saponins from under ground parts of Gypsophila arrostii var. nebulosa allowed the isolation of two triterpene saponins; nebuloside A, B based on gypsogenin and quillaic acid aglycone. Two new oleanane type triterpenoid saponins (nebuloside A, B) and three known saponins (1-3) were isolated from the root bark of Gypsophila arrostii var. nebulosa. The structures of the two new compounds were elucidated as 3-O-ß-d-galactopyranosyl-(1›2)-[ß-d-xylopyranosyl-(1›3)]- ß-d-glucuronopyranosyl quillaic acid 28-O-ß-d-glucopyranosyl- (1›3)-[ß-d-xylopyranosyl-(1›3)-ß-d-xylopyranosyl-(1›4)] -?-l-rhamnopyranosyl-(1›2)-ß-d-fucopyranosyl ester (nebuloside A) and 3-O-ß-d-xylopyranosyl-(1›3)-[ß-d- galactopyranosyl(1›3)-ß-d-galactopyranosyl-(1›2)] -ß-d-glucuronopyranosyl gypsogenin 28-O-ß-d-glucopyranosyl-(1›3)- [ß-d-xylopyranosyl-(1›3)-ß-d-xylopyranosyl-(1›4)] -?-l-rhamnopyranosyl-(1›2)-ß-d-fucopyranosyl ester (nebuloside B), on the basis of extensive spectral analysis and chemical evidence. Nebuloside A and B showed toxicity enhancing properties on saporin a type-I RIP without causing toxicity by themselves at 15 µg/mL. © 2012 Elsevier Ltd. All rights reserved.