Structure-nephrotoxicity relationships of glutathione pathway intermediates derived from organic solvents

Abstract

The nephrotoxicity of glutathione (GSH) pathway metabolites derived from toluene (TOL), styrene (STYR), bromobenzene (BB), acrylonitrile (ACLN) and 2-chloroacrylonitrile (CACLN) were compared with that of dichlorovinylcysteine (DCVC), using renal brush border and basal-lateral uptake parameters as indices. Cysteine conjugates and mercapturates of ACLN did not alter p-aminohippurate (PAH) uptake by renal tubule suspensions in contrast to its chlorinated homologue. O-, m- and p-conjugates of BB inhibited PAH uptake by 43–82%, the mercapturates showing more potency than corresponding cysteine conjugates. The TOL derivatives N-acetylbenzylcysteine curtailed PAH uptake but benzylcysteine was more effective. The GSH conjugate and mercapturate synthesized from STYR oxide were also active inhibitors but not its cysteine conjugate. Among all GSH pathway metabolites studied, only DCVC and phenylhydroxyethylglutathione, derived from STYR oxide, impeded the renal basal-lateral uptake of [ 14C]tetraethylammonium (TEA) while DCVC was the sole inhibitor of brush border transport events such as the uptakes of [ 3H]glutamate and [ 14C]α-methyl- D-glucoside. These data indicate that GSH conjugation represents a non-nephrotoxic detoxication pathway for ACLN. In contrast, GSH conjugation with 2-chloroacrylonitrile and with aromatic solvents like TOL, STYR, BB gives rise to nephrotoxic mercapturates which may be less potent but show more specificity for the organic anion transport system than DCVC.