EFFECT OF THIOL COMPOUNDS ON EXPERIMENTAL LIVER-DAMAGE .4. DETOXICATING EFFECT OF TIOPRONIN, GLUTATHIONE AND CYSTEINE ON ETHIONINE INDUCED LIVED DAMAGE

S-GPT elevated due to ethionine (Eth) administration was suppressed by thiol compounds such as tiopronin (2-mercaptopropionylglycine), glutathione, cysteine, in which tiopronin proved to be more effective than glutathione or cysteine. In thin-layer chromatography of urinary metabolites, Eth and ethionine sulfoxide were detected with administration of Eth, and S-ethyltiopronin plus Eth and ethionine sulfoxide by the administrations of Eth and tiopronin. These S-ethyl derivatives were not detected in the urine with administration of Eth and glutathione or cysteine. In the analysis of Eth and its metabolites by gas chromatography, cumulative urinary excretion of Eth within 72 hr after Eth administration was 40.7% in the Eth administered group, 23.6% in the Eth-tiopronin administered group and 38.2% in the Eth-glutathione administered group, respectively. In the urine of the Eth-tiopronin administered group, S-ethyltiopronin was excreted by 13.6%. Detoxicating effect of tiopronin on Eth induced liver damage was considered to involve the following mechanism. Tiopronin is considered to excrete part of Eth as S-ethyltiopronin by being an acceptor of transfer reaction of the ethyl group of Eth. Neither glutathione nor cysteine was an acceptor of the ethyl group and a detoxicating effect on Eth was not observed. © 1979, The Japanese Pharmacological Society. All rights reserved.