Antibacterial Activities of Novel Dithiocarbamate-Containing 4<i>H</i>-Chromen-4-one Derivatives

Abstract

To aid the development of novel antibacterial agents that possess a innovative mechanism of action, we built a series of novel dithiocarbamate-containing 4<i>H</i>-chromen-4-one derivatives. We evaluated the activities of the derivatives against three plant pathogens <i>Xanthomonas oryzae</i> pv <i>oryzae</i> (<i>X. oryzae</i> pv <i>o</i>.), <i>Ralstonia solanacearum</i> (<i>R. solanacearum</i>), and <i>Xanthomonas axonopodis</i> pv <i>citri</i> (<i>X. axonopodis</i> pv <i>c</i>.). The results of the antibacterial bioassay showed that most of the target compounds displayed good inhibitory effects against <i>X. oryzae</i> pv <i>o</i>. and <i>X. axonopodis</i> pv <i>c</i>. Remarkably, compound <b>E6</b> showed the best <i>in vitro</i> antibacterial activity against <i>X. axonopodis</i> pv <i>c</i>., with an EC₅₀ 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 <b>E14</b> exhibited the best <i>in vitro</i> antibacterial activity against <i>X. oryzae</i> pv <i>o.</i>, with an EC₅₀ 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 <b>E6</b> and <b>E14</b> caused the rupture or deformation of the cell membranes for <i>X. axonopodis</i> pv <i>c</i>. and <i>X. oryzae</i> pv <i>o.</i>, respectively. <i>In vivo</i> antibacterial activity test and the defensive enzymes activity test results indicated that the compound <b>E14</b> could reduce <i>X. oryzae</i> pv <i>o</i>. more effectively than thiodiazole-copper or bismerthiazol.