Synthesis and antibacterial activity of novel chalcone derivatives bearing a coumarin moiety

A series of novel chalcone derivatives, that bear a coumarin moiety, were designed and synthesized, and their structures were confirmed via 1H NMR, 13C NMR, and H RMS. The bioassay results indicated that most title compounds exhibited remarkable antibacterial effects. Notably, compound 3a presented the most efficient antibacterial activity against Xanthomonas oryzae pv. Oryzae (Xoo), with median effect concentration (EC50) value of 49.77 μg/mL, which was far preferable than that of thiodiazole–copper (179.93 μg/mL). Meanwhile, compound 3n was identified as the best potential antibacterial agent against Xanthomonas axonopodis pv. citri (Xac), with EC50 value of 48.04 μg/mL, which far surpassed that of thiodiazole–copper (162.48 μg/mL). Furthermore, compound 3i indicated excellent antibacterial activity against Ralstonia solanacearum (Rs), with EC50 value of 65.04 μg/mL, which was far superior to that of thiodiazole–copper (126.89 μg/mL). This study indicated that chalcone hybrids, bearing a coumarin moiety, are worthy of further investigation as potential antibacterial drugs.