THE EFFECT OF SULFHYDRYL COMPOUNDS ON THE ANTISPIROCHETAL ACTION OF ARSENIC, BISMUTH, AND MERCURY COMPOUNDS IN VITRO

¹ From the United States Public Health Service, Washington, and the Syphilis Division of the Department of Medicine, Johns Hopkins Medical School, Baltimore

Sulfhydryl compounds (cysteine, glutathione, and thioglycollic acid) added in sufficient excess to arsphenamine, neoarsphenamine, silver arsphenamine, "arsenoxide," bismuth, or mercury compounds, almost completely abolish their antispirochetal action in vitro. The large excess which is necessary to cause complete inactivation of the arsenicals suggests that the addition compound may be readily hydrolyzed. Thiamin chloride and methionine, which contain a —S— rather than a —SH group, have no inhibitory effect.

The thesis that the antispirochetal action of arsenic, bismuth, and mercury compounds may rest on their common affinity for sulfhydryl groups in the T. pallidum is discussed in the text.