Design, synthesis, and antibacterial activity evaluation of tryptanthrin derivatives

A series of tryptanthrin derivatives were designed, synthesized and evaluated for their antibacterial activity against the marine pathogen Vibrio parahaemolyticus. The bioactivity assessment revealed that compounds 7h and 8c exhibited potent antibacterial effects against V. parahaemolyticus without cytotoxicity toward mammalian cells. Structure-activity relationship (SAR) analysis indicated that electron-withdrawing substituents on the phenyl ring played a crucial role in enhancing antibacterial activity. Furthermore, compounds 7h and 8c demonstrated strong antibiofilm activity at concentrations of 8 μg/mL and 6 μg/mL, respectively, effectively inhibiting both biofilm formation and maturation in V. parahaemolyticus. These results demonstrate that compounds 7h and 8c exhibited efficacy against drug-resistant Vibrio strains, providing insight into the application of tryptanthrin derivatives as potential antibacterial agents.