PHOTOSENSITIVITY IN SOUTH-AFRICA .7. CHEMICAL-COMPOSITION OF BILIARY CRYSTALS FROM A SHEEP WITH EXPERIMENTALLY-INDUCED GEELDIKKOP

Geeldikkop was induced in a sheep by oral administration of crude sapo nins from Tribulus terrestris. Centrifugation of the bile from this sh eep gave a pale green sediment of crystalloid material which was insol uble in common organic solvents, but soluble in acetic acid. Analysis of the crystalloid material by H-1 and C-13 NMR, EDXA, TLC, LSIMS, and by acidic hydrolysis followed by TLC and GC-MS, revealed it to be com posed principally of a 6:1 mixture of the calcium salts of the beta-D- glucuronides of the steroidal sapogenins epismilagenin and episarsasap ogenin. The administered saponin was found to contain glycosides of th e steroidal sapogenins diosgenin, yamogenin, epismilagenin, tigogenin, neotigogenin, gitogenin and neogitogenin in the ratio 10:7:1:11:7:35: 25. A metabolic pathway for the conversion of diosgenin and yamogenin saponins to the biliary glucuronides is proposed.