Design, Synthesis, Antifungal, and Antioxidant Activities of (E)-6-((2-Phenylhydrazono)methyl)quinoxaline Derivatives

Different substituted phenylhydrazone groups were linked to the quinoxaline scaffold to provide 26 compounds (6a-6z). Their structures were confirmed by H-1 and C-13 NMR, MS, elemental analysis, and X-ray single-crystal diffraction. The antifungal activities of these compounds agains rhizoctonia solani were evaluated in vitro. Compound 6p is the most promising one among all the tested comp;ounds with an EC50 of 0.16 mu g.mL(-1), more potent than the coassayed positive control fungicide carbendazim (EC50 1.42 mu g.mL(-1)). In addition, these compounds were subjected to antioxidant assay by employing diphenylpicrylhydrazly (DPPH) and mice microsome lipid peroxidation (LPO) methods. Most of these compounds are potent antioxidantas. The strongest compounds are 6e (EC50. 7.60 mu g.mL(-1), DPPH) AND 6a (EC50. 0.96 mu g.mL(-1), LPO), comparative to or more potent than the positive contorl Trolox [EC50 5.90 mu g.mL-1 (DPPH) and 18.23 mu g.mL-1 (LPO)]. The structure and activity relationships were also discussed.