title: Involvement of the intestinal microflora in the formation of sulphur-containing metabolites of caffeine.
abstract: 1. The urine of conventional and germ-free rats was examined, after an oral dose of caffeine, with regard to the presence of sulphur-containing conjugates of this compound. 2. Only the methyl sulphoxide analogue was detected. 3. The ratio of the quantities of this metabolite in conventional and germ-free rat urine was 42:1. 4. The proposed mechanism for the formation of the methyl sulphoxide analogue of caffeine involves the biliary excretion of a mercapturic acid pathway metabolite of caffeine with subsequent metabolism by the intestinal microflora.
mesh_terms: D000818:Animals; D001711:Biotransformation; D002110:Caffeine / Q000378:metabolism*; D005856:Germ-Free Life; D007422:Intestines / Q000382:microbiology*; D051381:Rats; D013455:Sulfur / Q000378:metabolism*
chemical_list: D002110:Caffeine; D013455:Sulfur