Biotransformation of the fungicides hexachlorobenzene and pentachloronitrobenzene

Abstract

This overview of the metabolism of the fungicides hexachlorobenzene (HCB) and pentachloronitrobenzene (PCNB) indicates similarities in their pathways of biotransformation. Several metabolites of HCB and PCNB, such as chlorinated benzenes, the mercapturic acid, thiophenols, thioanisoles and phenols are identical. Both fungicides initially react with glutathione, with elimination of chlorine or of the nitro group respectively. The conjugate, S-(pentachlorophenyl)glutathione, is further metabolized by cleavage of the glutamate and glycine residues and acetylation of the amino group of the cysteinyl moiety, to give the mercapturic acid N-acetyl-S-(pentachlorophenyl)cysteine, a major metabolite of HCB and PCNB in rats and rabbits respectively, which is further metabolized to simpler sulphur-containing products.