Metabolism of Some Insecticides and Related Compounds in Mammals and Insects

Abstract

In part 1, a brief survey has been made of the microsomal oxidations carried out by both mammals and insects. In part 2, the N-methyl oxidation of both cresyland isopropylphenyl N methylcarbamates by mouse-liver preparations has been measured and compared. The oxidation rates of both series increase in the order m < p < o < unsubstituted. The effects of substrate concentration, storage, and semicarbazide on the N-methyl oxidation were also investigated. Both houseflies and grass grubs were shown to metabolise o-(isopropoxy-1,3-14C) phenyl N methylcarbamate by removal of the side chain as acetone-1,3-14C. The removal rate was greater for flies than for grass grubs. The cresyl-, isopropylphenyl-, and m-tertiarybutyl-phenyl N-methylcarbamates were shown to be metabolized by mouse liver by more than one route, the cresyl N-methylcarbamates in particular undergoing aryl side-chain hydroxylation. In part 3, p-nitrotoluene, p-acetamidotoluene, p-nitrobenzyl alcohol, and p-aminobenzyl alcohol were shown to be metabolised by grass grubs to the corresponding benzoic acid derivatives. p-Toluidine was not metabolised in this manner. Variation in the rates of oxidation of the, toluenes by individual grass grubs was greater than the variations obtained with the benzyl alcohols. The rates of oxidation of the toluenes by grass grubs were considerably less than the rates of oxidation of the benzyl alcohols. In part 4, evidence is presented for the multipathway degradation of Folithion by mouse-liver preparations. Oxon formation as well as desmethylation appear to be major pathways. Evidence is also presented for ring-methyl oxidation of Folithion.