Antibacterial Activities of Novel Dithiocarbamate-Containing 4H-Chromen-4-one Derivatives

To aid the development of novel antibacterial agents that possess a innovative mechanism of action, we built a series of novel dithiocarbamate-containing 4 H -chromen-4-one derivatives. We evaluated the activities of the derivatives against three plant pathogens Xanthomonas oryzae pv oryzae ( X. oryzae pv o .), Ralstonia solanacearum ( R. solanacearum ), and Xanthomonas axonopodis pv citri ( X. axonopodis pv c .). The results of the antibacterial bioassay showed that most of the target compounds displayed good inhibitory effects against X. oryzae pv o . and X. axonopodis pv c . Remarkably, compound E6 showed the best in vitro antibacterial activity against X. axonopodis pv c ., with an EC 50 value of 0.11 μg/mL, which was better than those of thiodiazole copper (59.97 μg/mL) and bismerthiazol (48.93 μg/mL). Compound E14 exhibited the best in vitro antibacterial activity against X. oryzae pv o., with an EC 50 value of 1.58 μg/mL, which was better than those of thiodiazole copper (83.04 μg/mL) and bismerthiazol (56.05 μg/mL). Scanning electron microscopy analysis demonstrated that compounds E6 and E14 caused the rupture or deformation of the cell membranes for X. axonopodis pv c . and X. oryzae pv o., respectively. In vivo antibacterial activity test and the defensive enzymes activity test results indicated that the compound E14 could reduce X. oryzae pv o . more effectively than thiodiazole-copper or bismerthiazol.