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

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-beta-D-galactopyranosyl-(1 -> 2)-[beta-D-xylopyranosyl-(1 -> 3)]-beta-D-glucuronopyranosyl quillaic acid 28-O-beta-D-glucopyranosyl-(1 -> 3)-[beta-D-xylopyranosyl-(1 -> 3)-beta-D-xylopyranosyl-(1 -> 4)]-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-fucopyranosyl ester (nebuloside A) and 3-O-beta-D-xylopyranosyl-(1 -> 3)-[beta-D-galactopyranosyl(1 -> 3)-beta-D-galactopyranosyl-(1 -> 2)]-beta-D-glucuronopyranosyl gypsogenin 28-O-beta-D-glucopyranosyl-(1 -> 3)-[beta-D-xylopyranosyl-(1 -> 3)-beta-D-xylopyranosyl-(1 -> 4)]-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-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 mu g/mL. (C) 2012 Elsevier Ltd. All rights reserved.