Crystals isolated from the bile of sheep affected by hepatogenous photosensitization after grazing Panicum dichotomiflorum or Panicum schinzii were soluble in acetic acid but essentially insoluble in common organic solvents. The main component of the crystals was identified by acidic and enzymatic hydrolysis, GC-MS, LSIMS, TLC, and 13C NMR spectroscopy, and X-ray analysis as the calcium salt of epismilagenin /S-D-glucuronide. The 13C NMR spectrum was fully assigned, and the structure confirmed by comparison with model compounds (17-oxoetiocholan-3a-ol glucuronide and epismilagenin). Only saponins derived from diosgenin were detected in the foliage of P. dichotomiflorum and P. schinzii. A metabolic pathway for conversion of P. dichotomiflorum and P. schinzii saponins into the major bile crystal component is proposed.

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Bracken fern (Pteridium esculentum) was harvested from two sites LB and TB one of which (TB) was on a central North Island New Zealand farm where bovine enzootic haematuria (BEH) was known to occur. The fern was dried, ground and incorporated (25% w/w) into a pelleted diet and fed to female rats for a total of 162 days. Fifteen weeks later when the rats were autopsied it was found that numerous tumours, mainly of the ileum and urinary bladder were present in the animals fed the bracken fern from the TB site. Neoplasms were found in 85% of rats from the TB group compared with 11% in the LB group while only a single tumour (a haemangioma of the uterus) was observed in the controls. In all, there were neoplasms in 42, 5 and 1 organ/s from the TB, LB and control rat groups respectively (p<0.001). Analysis of the fern and pellets for ptaquiloside, the carcinogen in bracken fern, showed much higher levels present in the material from the TB site. There was 26 and 2270 microg ptaquiloside/g of dried fern and, for pellets from the same fern, 6.5 and 355 microg ptaquiloside/g of pellets, for one collection from the LB and TB sources respectively.