Design, Synthesis and Antimicrobial Activity of Substituted Amine and Benzothiazole-Based Cyclopropane Carboxamides

The antimicrobial potential of synthesized derivatives A1–A5 and B1–B5 was evaluated against Gram-negative bacteria (P. aeruginosa, E. coli), Gram-positive bacteria (S. aureus, B. subtilis), and C. albicans using minimum inhibitory concentration (MIC, µg/mL) and zone of inhibition (ZOI, mm) assays. Among Gram-negative strains, B2 exhibited the best activity against P. aeruginosa (MIC 80 µg/mL; ZOI 12 mm), followed by B1 (MIC 160 µg/mL; ZOI 12 mm), whereas all compounds were inactive against E. coli (MIC ≥320 µg/mL; ZOI 10 mm). Significant Gram-positive activity was observed for A4 and A5 against S. aureus (MIC 10 µg/mL; ZOI 14–15 mm). A4 also showed potent activity against B. subtilis (MIC 10 µg/mL; ZOI 12 mm), while B3 demonstrated notable inhibition (MIC 320 µg/mL; ZOI 26 mm). In antifungal screening, A1 and B1 displayed promising activity against C. albicans (MIC 20 µg/mL; ZOI 15 and 22 mm, respectively). These findings indicate selective and moderate antimicrobial efficacy among the tested derivatives.