Antileishmanial and Antibacterial Activities of Aminobenzothiazole Sulfonamides

Leishmaniasis and multidrug-resistant (MDR) bacterial infections remain major global health challenges due to drug toxicity and increasing antimicrobial resistance. In this study, a library of previously synthesized N-sulfonylated and N-alkylated aminobenzothiazole derivatives (19–39) was evaluated for antileishmanial and antibacterial activities. Antileishmanial screening against Leishmania tropica (Khyber Medical University-KMU 25 strain) using a promastigote viability assay revealed IC₅₀ values ranging from 57.10–415 µg mL-1, with compounds 27 (N-allyl-N-(benzo[d]thiazol-2-yl)-4-bromobenzenesulfonamide),  (IC₅₀ = 57.10 ± 5.02 µg mL-1) and 23 (N-(benzo[d]thiazol-2-yl)-N-benzyl-4-fluorobenzenesulfonamide),  (IC₅₀ = 68.07 ± 6.03 µg mL-1) showing the highest potency. Antibacterial activity, assessed by agar well diffusion and microbroth dilution, indicated that compounds 19 (N-(benzo[d]thiazol-2-yl)-N-benzyl-4-methylbenzenesulfonamide), 21 (N-(benzo[d]thiazol-2-yl)-N-benzyl-4-chlorobenzenesulfonamide), 22 (N-(benzo[d]thiazol-2-yl)-N-benzyl-4-nitrobenzenesulfonamide), 27 (N-allyl-N-(benzo[d]thiazol-2-yl)-4-bromobenzenesulfonamide), and 31  (N-allyl-N-(benzo[d]thiazol-2-yl)benzenesulfonamide), exhibited notable inhibition against Escherichia coli and Staphylococcus aureus, with MIC values ranging from 0.15 to 0.43 µg mL-1. These results identify aminobenzothiazole sulfonamides as promising dual-active scaffolds with potential relevance for future development of antileishmanial and antibacterial agents.