Synthesis of novel antibacterial and antifungal quinoxaline derivatives.

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 in vitro . Compound 5k displayed good antibacterial activity against Acidovorax citrulli ( Ac ). Compounds 5j and 5t exhibited the most potent anti- RS ( Rhizoctonia solani ) activity, with the corresponding EC 50 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 RS . Moreover, an in vivo bioassay also demonstrated that the anti- RS activity of compound 5j could effectively control rice sheath blight. These results indicate that quinoxaline derivatives could be promising agricultural bactericides and fungicides.