The metabolism of ellagic acid in the rat.

1. Following oral administration of ellagic acid to the rat, 10% of the dose was excreted as 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one in urine and faeces. A second metabolite was detected in urine and faeces but not identified. Both metabolites were of microfloral origin, as their formation was not observed in germ-free rats but was demonstrated when ellagic acid was incubated in vitro with micro-organisms from rat gastro-intestinal tract. 2. Following intraperitoneal, but not oral, administration of ellagic acid, a third metabolite was detected in urine. 3. Unchanged ellagic acid was not detected in faeces or urine of any normal rat examined, but small amounts were detected in the faeces of germ-free animals. 4. Following oral administration of ellagic acid, two conjugates of 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one were detected in bile, whereas intraperitoneal administration resulted in the biliary excretion of three conjugates of an unidentified metabolite.