S-oxygenation of thiobencarb (Bolero) in hepatic preparations from striped bass (Morone saxatilis) and mammalian systems

Publisher Website
Google Scholar
Abstract
The in vitro S-oxygenation of thiobencarb (Bolero; p-chlorobenzyl N,N-diethylthiocarbamate) in the presence of hepatic microsomes from freshwater- and seawater-adapted striped bass was investigated. Thiobencarb S-oxide was the principal metabolite and accounted for 98% of the total thiobencarb metabolized by striped bass liver microsomes. Studies on the biochemical mechanisms for striped bass hepatic S-oxygenation suggest that this reaction is catalyzed largely by the flavin-containing monooxygenase and to a lesser extent by cytochromes P-450. Following the short incubation period used, no thiobencarb sulfone was detected and no evidence was found for a contribution of cooxidation in the S-oxidation of thiobencarb. This conclusion was supported by studies with microsomes and purified mammalian monooxygenases which also metabolized thiobencarb without cooxiding factors. Highly purified cytochrome P-450IIB-1 S-oxygenated thiobencarb more efficiently than highly purified hog liver flavin-containing monooxygenase. Thiobencarb S-oxide and thiobencarb sulfone were efficient carbamylating agents and reacted with thiol and amine nucleophiles, whereas thiobencarb itself was relatively stable to transthiocarbamylation. Monooxygenase-catalyzed S-oxygenation of thiobencarb by striped bass liver microsomes may represent a bioactivation process which could explain the known toxicity of thiobencarb in fish.

This publication has 15 references indexed in Scilit: