OXIDATIVE METABOLISM OF PYRETHROIDS IN HOUSEFLIES

Allethrin is metabolized in living houseflies (Musca domestica L.) and in the housefly mixed-function oxidase system by attack at the trans-(major site) and cH-(minor site) methyl groups of the isobutenyl side chain in the acid forming, in succession, the corresponding hydroxymethyl, aldehyde, and acid compounds. No hydrolysis or attack on the alcoholic part of the ester is detected, but there are trace amounts of unidentified metabolites. Piperonyl butoxide inhibits hydroxylation of the methyl groups by the mixed-function oxidase system. Living houseflies conjugate and excrete the hydroxymethyl compounds, probably as glucosides. Pyrethrin I, phthalthrin, and dimethrin are similarly metabolized, in vivo and in vitro, by oxidation of the rrarw-methyl group. © 1969, American Chemical Society. All rights reserved.