Synthesis of novel antibacterial and antifungal quinoxaline derivatives

Abstract

A series of quinoxaline derivatives were designed, synthesized and evaluated as antimicrobial agents against plant pathogenic bacteria and fungi. Some of these compounds exhibited significant antibacterial and antifungal activities <i>in vitro</i>. Compound 5k displayed good antibacterial activity against <i>Acidovorax citrulli</i> (<i>Ac</i>). Compounds 5j and 5t exhibited the most potent anti-<i>RS</i> (<i>Rhizoctonia solani</i>) activity, with the corresponding EC₅₀ values of 8.54 and 12.01 μg mL^-1, respectively, which are superior to that of the commercial azoxystrobin (26.17 μg mL^-1). Further, the scanning electron microscopy results proved that compound 5j had certain effects on the cell morphology of <i>RS</i>. Moreover, an <i>in vivo</i> bioassay also demonstrated that the anti-<i>RS</i> activity of compound 5j could effectively control rice sheath blight. These results indicate that quinoxaline derivatives could be promising agricultural bactericides and fungicides.