[Pharmacological studies of new sulfhydryl compounds 2-mercapto-2-methylpropanoyl-L-cysteine (SA96). I. Evaluation of anti-rheumatic action (author's transl)].

Oral administration of 2-mercapto-2-methylpropanoyl-L-cysteine (SA 96), a newly synthesized sulfhydryl compound, showed protective and curative effects on adjuvant-induced arthritis in rats similarly to those seen with D-penicillamine (D-PA). However, the effects of these compounds were not dose-dependent, and the maximum effects of SA96 were observed at 10 mg/kg/day. On the contrary, SA96 and D-PA had little effect on the various acute and subacute inflammatory responses induced in rat and mice. Formation of hemolytic plaque forming cells in the spleen of mice immunized with 5 X 10(8) sheep red blood cells was potentiated by the oral administration of both compounds. These stimulatory effects of SA96 and D-PA on the humoral immune responses were also not dose-dependent, and the maximum effects of SA96 were observed with 10 mg/kg/day, as in the case of adjuvant-induced arthritis in rats. In in vitro experiments, the inactivation of rheumatoid factor and the inhibition of collagenase and bone alkaline phosphatase activities were observed with both compounds, but these effects of SA96 were more potent than those of D-PA. As there is a similarity in the pharmacological profiles of SA96 and D-PA, SA96 may prove to be clinically effective for rheumatoid arthritis.