Synthesis and Antimicrobial Action of Ninhydrin, Isatin, and 5-Acetyl-4-Hydroxy-1,3-Thiazine-2,6-Dione Derivatives Against Staphylococcus aureus and Pseudomonas aeruginosa Opportunistic Microflora

Series of new derivatives of ninhydrin, isatin, and 4-hydroxy-1,3-thiazine-2,6-dione were synthesized. Their antimicrobial activity against opportunistic microflora of Staphylococcus aureus and Pseudomonas aeruginosa isolated from neurotrophic ulcers of leprosy patients was studied. Antibacterial activity against S. aureus was observed for derivatives of chalcone (MIC 2.31 ± 0.99 and 8.0 ± 2.83 μg/mL), benzofuran (MIC 3.5 ± 1.66 μg/mL), imines (MIC 0.56 ± 0.16 and 3.01 ± 1.68 μg/mL), and indene (MIC 1.38 ± 0.38 μg/mL). Derivatives of imine (MIC 0.25 ± 0.05 and 0.63 ± 0.26 μg/mL) and indene also exhibited pronounced inhibitory effects against P. aeruginosa. Bactericidal effects on both cultures were observed for 5-{(1E)-1-[2-(1-benzothiophen-2-yl)hydrazinylidene]-ethyl}-4-hydroxy-2H-1,3-thiazine-2,6(3H)-dione. An indene derivative with a morpholine fragment showed a pronounced bactericidal effect (MBC 2.3 ± 0.58 μg/mL) on the growth of P. aeruginosa culture.