The antitubercular properties of a series of thiols and sulphides

The antitubercular activity of a series of thiols, dithiolans, thiol esters, dimercaptopropyl esters, and episulphides has been examined in vitro and in vivo in mice infected with the H(37)Rv strain of Mycobacterium tuberculosis. Most of the thiol compounds were inactive, although dimercaprol (2,3-dimercaptopropanol; B.A.L.) and a few closely related compounds showed slight activity in vivo, the only exception being 2,3-dimercaptopropyl chloride which was very active. The dithiolans were inactive, but some of the thiol esters were moderately active, in particular 2,3-di(acetylthio)propyl acetate and 1,2,3-tri(acetylthio)propane. The majority of the dimercaptopropyl esters had significant activity, the most active compounds being 2,3 - dimercaptopropyl benzoate, 1, 3 - dimercapto - 2 - propyl benzoate, 2, 3 - dimercaptopropyl o-chlorobenzoate, and 2,3-dimercaptopropyl p-chlorobenzoate. All the S-acyl derivatives of 3-mercaptopropylene sulphide had good antitubercular activity, some being more active than streptomycin. The most active compound of the series was 3-(2-furoylthio)propylene sulphide. The activity of the compounds is believed to be due to their conversion in vivo to 3-mercaptopropylene sulphide and not due to the formation of ethanethiol. Slight deviation from the basic structure abolishes antitubercular activity.