Fate of TR-2, the hepatic metabolite of the tremorgenic mycotoxin verruculogen, in sheep. 
1.  Verruculogen is eliminated in bile after transformation to TR-2, only a trace of which was excreted as such in faeces of sheep given verruculogen per os.  Negligible TR-2 was present free in urine; no glucuronide was found.  2.  An isomer of TR-2, a minor component of the bile of sheep given verruculogen, has been defined by 1H-n.m.r.  spectroscopy and the isomerism involves the disposition of the two adjacent hydroxyl groups with a concomitant change in the conformation of the ring adjacent to the indole.  3.  14C-TR-2, added to the perfusate of isolated rat liver, was excreted unchanged in the bile, implying no significant loss of any biliary TR-2 subject to enterohepatic recycling in vivo.  4.  14C-TR-2 incubated anaerobically in sheep ileum contents was 95% transformed into more polar metabolites, the majority of the radiolabelled metabolites isolated being water soluble.  5.  The principal fate of biliary TR-2 is as a metabolic substrate for the intestinal microflora.