IN-VITRO METABOLISM OF THE NEW INSECTICIDE FLUPYRAZOFOS BY RAT-LIVER MICROSOMES

1. The in vitro metabolism of the new insecticide flupyrazofos was stu died using rat liver microsomes. Two metabolites were produced and ide ntified as O,O-diethyl O-(1-phenyl-3-trifluoromerhyl-5-pyrazopl) phosp horic acid ester (flupyrazofos oxon) and 1-phenpl-3-trifluoromechyl-5- hydroxypyrazole (PTMHP) based on UV and mass spectral analysis. 2. Cyt ochrome P450 oxidatively converted flupyrazofos to flupyrazofos oxon, a major metabolite and phenobarbital-induced microsomes increased this desulphuration by 8-fold. 3. Flupyrazofos oxon was converted to PTMHP with a half-life of 47.8 min by chemical hydrolysis and this conversi on also proceeded non-enzymatically under our microsomal incubation co nditions.