IN-VITRO TRANSFORMATION OF THIAZOPYR BY RAT-LIVER ENZYMES - SULFUR AND CARBON OXIDATIONS BY MICROSOMES

Thiazopyr is an experimental herbicide from the pyridine family that shows excellent preemergent activity against narrow-leafed weeds. Biotransformation of thiazopyr was examined in vitro using rat liver microsomes to assess the extent of its metabolism in vivo. Thiazopyr was rapidly and extensively oxidized exclusively in the thiazoline ring. The sulfur atom in the thiazoline ring was sequentially oxidized to the corresponding sulfoxide and sulfone metabolites. Oxidation of the carbon atoms in the thiazoline ring produced carbinolimine intermediates, which underwent dehydration or arrangements leading to the opening of thiazoline ring. A total of six metabolites were identified based on electrospray LC/MS and/or cochromatography with standards. © 1993 Academic Press, Inc.