Thein vitrometabolism of lindane by an enzyme preparation from chicken liver¹

Abstract

The soluble fraction (105,000 x g, 30 min) of chicken liver homogenates contained an enzyme(s), probably a dehydrochlorinase(s), which metabolized lindane in vitro. The reaction was glutathione dependent and took place anaerobically. The enzyme(s) also metabolized the alpha- and delta-isomers but not the beta-isomer. About 66% of the in vitro metabolites were soluble in petroleum ether. From the ether-soluble fraction, o-, p- amd m-dichlorobenzene, 1,2,3- and 1,2,4-trichlorobenzene, gamma-2,3,4,5,6-pentachlorocyclohex-1-ene (gamma-PCCH), 2,3- and 2,4-dichlorophenol and 2,4,6-trichlorophenol were identified by comparison of mass spectra and gas chromatographic data with those of reference compounds. Seven additional metabolites were tentatively identified from their mass spectra data. These metabolites were: chlorobenzene, 2 isomers of trichlorocyclohexene, dichlorocyclohexadienetriol, chlorophenol, trichlorocyclohexenol and trichlorocyclohexanediol. The petroleum ether-extracted aqueous phase contained a number of unidentified conjugated metabolites. It was concluded that the metabolic pathway for lindane in the chicken is quite similar to that in the pheasant.

Acute toxicity and metabolism of pesticides in birds

“…The oxidation of alkyl and/or aryl moieties is frequently observed, as well as the hydrolysis of the ester and amide linkages. Reduction occurs less than oxidation, for example, for the chlorinated alkyl moieties of lindane 109) and DDT, 111) the nitro group of parathion, 67) and the ketone of warfarin. 68) O-Glucuronidation of the phenolic oxygen often proceeds in the metabolism, as reported for cypermethrin, 82) carbaryl, 91) NMC, 102) and methoxychlor, 112) while conjugations with a sulfate or glutathione are less observed.…”

“…Although information on the stereo-selective reduction of pesticides is very limited, the degradation of HCH in the hepatic cytosolic fraction of laying hens is highly dependent on its isomerism. 109) The γ-isomer (lindane) rapidly underwent dehydrochlorination, but the reaction was much slower for α-and δ-isomers, and no metabolism of β-isomers was observed.…”

Opinion of the Scientific Panel on contaminants in the food chain [CONTAM] related to gamma-HCH and other hexachlorocyclohexanes as undesirable substances in animal feed

“…Evidence exist that fish are able to metabolise γ-HCH to polar and non polar metabolites after exposure via surrounding water (Görge and Nagel, 1990) but no data were found for dietary exposure. In birds, metabolism of γ-HCH has been investigated in hen pheasants (Saha and Burrage, 1976) and in vitro with subcellular fraction from chicken liver (Foster and Saha, 1978). In both cases the major metabolites were pentachlorobenzene, isomers of di-, tri, tetra-and corresponding chlorophenols.…”