Synthesis and Antibacterial Activity of Novel Phosphonate Derivatives Containing Flavonoids

By introducing flavonoids group into H-phosphonate, fourteen novel phosphonate derivatives containing flavonoid unit were designed and synthesized. Their structures were characterized by H-1 NMR, C-13 NMR, P-31 NMR, MS, IR and HRMS, and their antibacterial activities were evaluated via turbidimeter test in vitro. The bioassays results reveal that part of the target compounds exhibit better activities against Xanthomonas oryzae pv. Oryzae (Xoo) and Xanthomonas axonopodis pv. Citri (Xac) than positive controls thiodiazole copper and bismerthiazol (>= 57.4%). Among them, the inhibitory rates of (2-(2-methoxyphenyl)-7-methoxy-4-oxo-4H-chromen-3-yl) diethyl phosphonate (2b), (2-(2-methoxyphenyl)-7-ethoxy-4-oxo4H-chromen-3-yl) diethyl phosphonate (2f) and (2-(3,4-dimethoxyphenyl)-7-ethoxy-4-oxo-4H-chromen-3-yl) diethyl phosphonate (2m) reached 92.8%, 87.7% and 88.3% against Xoo at a concentration of 100 mu g/mL, respectively. In addition, the inhibitory rates of (2-(4-fluorophenyl)-7-ethoxy-4-oxo-4H-chromen-3-yl) diethyl phosphonate (2h) and (2-(p-tolyl)-7-ethoxy-4-oxo4H-chromen-3-yl) diethyl phosphonate (2k) reached 85.1% and 71.7% against Xac at a concentration of 100 g/mL, respectively.