[Antimicrobial effect of derivatives of 1,2,4-benzothiadiazin-1,1-dioxide. VII]

Series of alkyl derivatives of the following have been prepared: 5,7-dichloro- [compounds (II leads to V)], 6-methyl- [compounds (VI leads to IX)] and 6-methoxy-3-mercapto-1,2,4-benzothiadiazine-1,1-dioxide [compounds (X leads to XIII)]. The products were tested for antimicrobial activity. Studies were also made of the corresponding 3-mercapto precursors (XIV, XV, XVI) and the relative 3-picolinium salts (XVII, XVIII, XIX) and also of the 3-picolinium salts of 6-chloro-, 7-chloro- and 6,7-dichloro-3-mercapto-1,2,4-benzothiadiazine-1,1-dioxide (XX, XXI, XXII). Some of the 3-alkylmercapto compounds, and especially the 5,7-dichloro derivative, inhibited various strains of Gram-positive bacteria of the genus Staphylococcus, while the same substances proved much less effective against the genera Streptococcus and Diplococcus. Antimicrobial activity appeared to be influenced by the length of the alkyl chain as well as by the nature and position of the substituents on the benzene ring. The compounds proved inactive against the Gram-negative schizomycetes (Salmonella, Shigella, Escherichia, Proteus, Pseudomonas. Enterobacter, Klebsiella, Serratia, Yersinia, Providencia) and against yeasts (Candida) with the exception of compound (V) which showed slight bacteriostatic action against three strains of Candida albicans.