Isolation of steroidal sapogenins implicated in experimentally induced cholangiopathy of sheep grazing Brachiaria decumbens in Brazil

As part of an experimental study, crystal-associated cholangiopathy was ind uced in 9 sheep by grazing pure pastures of Brachiaria decumbens in Brazil. One of these sheep showed caracteristic lesions of photosensitization. The analysis of the B decumbens samples by acidic hydrolysis followed by TLC a nd infrared spectrum revealed diosgenin as the principal sapogenin present in the plant. In the rumen contents samples from the B decumbens-grazing gr oup were identified by TLC,H-1 and C-13 NMR and EIMS as epismilagenin, epis arsasapogenin, and a mixture of smilagenin acid sarsasapogenin. In the bile samples from the B decumbens-grazing group, TLC analysis demonstrated 2 co mpounds similar to epismilagenin and episarsasapogenin. However, by this sa me method, those compounds were not observed in the rumen contents and bile from 2 sheep which served as control animals. The P chartarum spore counts remained very low during the experimental period.