Photosensitivity in South Africa. VII. Chemical composition of biliary crystals from a sheep with experimentally induced geeldikkop.

Geeldikkop was induced in a sheep by oral administration of crude saponins from Tribulus terrestris. Centrifugation of the bile from this sheep gave a pale green sediment of crystalloid material which was insoluble in common organic solvents, but soluble in acetic acid. Analysis of the crystalloid material by 1H and 13C NMR, EDXA, TLC, LSIMS, and by acidic hydrolysis followed by TLC and GC-MS, revealed it to be composed principally of a 6:1 mixture of the calcium salts of the beta-D-glucuronides of the steroidal sapogenins epismilagenin and episarsasapogenin. The administered saponin was found to contain glycosides of the 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.

Hepatotoxic constituents in the rumen of Brachiaria decumbens intoxicated sheep.

Spectroscopic examinations of purified extracts of the rumen content of sheep intoxicated by Brachiaria decumbens revealed the presence of a mixture of sapogenins, identified as 3-spirostanols. These isomeric steroid sapogenins (C27H44O3) are believed the toxic principles in causing toxicity in sheep after feeding on B. decumbens.

Vaccination as a possible means of preventing lantana poisoning.

The toxic triterpene acids lantadene A and lantadene B were isolated from Lantana camara and conjugated to bovine serum albumen or haemocyanin. The conjugates were emulsified with complete Freund's adjuvant and injected into sheep and cattle. Vaccinated animals produced antibodies against the toxic compounds. Cholestasis was less severe in vaccinated than in non-vaccinated sheep challenged with a toxic dose of lantana. The results indicated a mild protective effect of vaccination against the hepatotoxic effects of lantana toxins.