Diabolic acids: occurrence and identification in natural products and their metabolism by simple-stomached and ruminant animals.

1. A method for gas-liquid chromatographic analysis of the dimethyl esters of a homologous series of diabolic acids is described. 2. Only when combined with low-resolution mass spectrometry could the method be used to show unequivocally the existence of diabolic acids in natural products. 3. Diabolic acids occurred naturally in rumen and faecal lipids of all ruminants examined but could not be detected in a number of ruminant tissue samples. 4. Infused 14C-labelled (C16:0)2 diabolic acid was poorly absorbed by both simple-stomached and ruminant animals. Oxidation was more extensive in the ruminant, but there was no evidence of deposition of diabolic acid in the tissues of either animal.