Studies on heterocyclic compounds: spiro [indole-3,2'-thiazolidine] derivatives. II. Antimicrobial activity of halogenated 3'-phenylspiro 3H-indole-3,2'-thiazolidine -2,4 (1H)-diones.

The following polyhalogenated 3'-phenyl 3H-indole-3,2'-thiazolidine -2,4' (1H)-dione of general formula (A) were synthesized and screened for antimicrobial activity. (formula: see text) where: X = H (I, III, V, VII, IX, XI), CH3 (II, IV, VI, VIII, X, XII); Y = H (I, II), 2,4-F2 (III, IV), 2,4-Cl2 (V, VI), 3,4-Cl2 (VII, VIII), 2,6-Cl2 (IX, X), 2,4,6-Cl3 (XI, XII). The general synthetic route involves the preparation of variously substituted isatin-3-imines, which are subjected to cyclocondensation with thioglycolic acid to give compounds I, III, V, VII, IX, XI, or thiolactic acid to give compounds II, IV, VI, VII, X, XII. The prepared compounds were screened against S. aureus, B. cereus, M. paratuberculosis, E. coli, Pr. mirabilis, Ps. aeruginosa, C. albicans, S. cerevisiae, A. niger by a disk-diffusion assay (Kirby-Bauer modified). The results of the antimicrobial screening showed that the polyhalogenated derivatives of type (A) exhibited varying degrees of activity against Gram-positive, Gram-negative bacteria, and fungi. Compound (III) showed a significant activity toward A. niger, moreover compound (IV) was active toward C. albicans. Compound (IX) was very active toward S. typhi and Ps. aeruginosa. Compounds (VII), (IX) and (XII) were very active toward M. paratuberculosis.