Derivatives of Rifamycin SV

1,165,179. Derivatives of rifamycin SV. GRUPPO LEPETIT S.p.A. 18 Oct., 1967 [25 Oct., 1966], No. 47899/66. Heading C2A. The invention relates to 3-thio derivatives of rifamycin SV of general formula wherein R is a carboxyalkyl, aminoalkyl, di- C 1 -C 8 alkylaminoalkyl, benzimidazolylethyl, 2- (carboxymethylcarbamyl) - 2 - (γ - amino - γ - carboxypropionamido) ethyl, guanidinoethyl, 2-acetamidoethyl or pyrrolidinomethyl. The compounds are prepared by reacting rifamycin S with 1 to 2À5 equimolecular amounts of a thio derivative of formula RSH in which R has the above significance, in an aqueous organic solvent for 20-120 minutes at 0‹ to 30‹ C. During the reaction, the 1,4-quinone group of rifamycin S is reduced to the 1,4-hydroquinone group of rifamycin SV. Typical compounds are 3-glutathionyl-, 3-(21-aminoethylthio)-, 3-(21- guanidinoethylthio)- and 3-pyrrolidinomethylthiorifamycin SV. The compounds have antibacterial activity. A therapeutic composition comprises a 3-thio derivative of rifamycin SV as above and a carrier.