Synthesis and Biological Activities of Myricetin Derivatives Containing Quinoxaline

According to the active substructure combination theory, a series of novel myricetin derivatives containing quinoxaline moieties was synthesized by introducing the quinoxaline blocks into the structures of myricetins. The antibacterial activities of the target compounds were evaluated via turbidimeter test in vitro. The preliminary bioassay results indicated that all of the title compounds exhibited certain antibacterial activities in vitro against Xanthomonas axonopodis pv. Citri (X. citri) and Xanthomonas oryzae pv. Oryzae (X. oryzae) . The compounds were also tested to evaluate the half maximal effective concentration (EC50) of phytopathogenic bacteria. The results showed that all the X. citri ECof the target compounds were superior to those of the control drugs of bismerthiazol and thiodiazole copper(54. 85 and 61. 13 mu g/mL, respectively) . Compound 4o (EC50 = 11. 17 mu g/mL) exhibited the best activity. All of the X. oryzae EC50 of the target compounds were superior to the control drugs of bismerthiazol and thiodiazole copper (148. 20 and 175. 47 mu g/mL , respectively) . Compound 4f(EC50= 34. 49 mu g/mL) exhibited the best activity. The in vivo efficacies against tobacco mosaic virus (TMV) of the target compounds were tested through half-leaf method. The results of bioassay showed that the target compounds exhibited certain anti-TMV activities at the concentration of 500 mg/L.