PHOTOSENSITIVITY IN SOUTH-AFRICA .9. STRUCTURE ELUCIDATION OF A BETA-GLUCOSIDASE-TREATED SAPONIN FROM TRIBULUS-TERRESTRIS, AND THE IDENTIFICATION OF SAPONIN CHEMOTYPES OF SOUTH-AFRICAN T-TERRESTRIS

Saponin C, a beta-glucosidase-treated saponin isolated from ethanol-wa ter extracts of a South African collection of Tribulus terrestris, was shown by one- and two-dimensional NMR spectroscopy to be ruscogenin 1 -O-alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-6-O-acetylglucopyranoside. GC-MS analysis of the hydrolysed ethanol-water (4:1) extracts of T. t errestris specimens from two of four sites, revealed high levels of ru scogenin and potentially lithogenic diosgenin saponins. Specimens from two other sites contained non-lithogenic saponins derived predominant ly from tigogenin, neotigogenin, gitogenin and neogitogenin.