Design,synthesis and biological evaluation of novel 3-phenylpropanamide derivatives with acyl hydrazone units

In this study, a series of 3-phenylpropanamide derivatives with acyl hydrazone units were synthesized and characterized by ¹H NMR, ¹³C NMR and HR MS. And the structure of compound III₃₃ was confirmed by X-ray single crystal. The bioassay results showed that, compounds III₈, III₁₇, III₂₂, and III₃₄ showed excellent inhibition on Xanthomonas oryzae pv. pryzae (Xoo) with EC₅₀ values of 7.1, 8.8, 9.5, and 4.7 μg/mL in vitro. The EC₅₀ values of compounds III₁₂, III₁₄ and III₃₃ against Ralstonia solanacearum (Rs) were 7.6, 7.6 and 7.9 μg/mL, respectively, all lower than the values of thiadiazol copper (TC) was 66.8 μg/mL and bismerthiazol (BT) was 72.4 μg/mL. Compounds III₁₂, III₁₄, III₃₃, and III₃₄ exhibited excellent antibacterial activity of more than 80% against Xanthomonas axonopodis pv. citri (Xac) in vitro. Besides, compounds III₈ (51.4%) and III₃₄ (52.1%) were highly effective against Xoo in vivo, outperforming TC (49.5%) and BT (47.8%). Compounds III₈ (29.8%) and III₃₄ (24.6%) were close to TC (41.7%) and BT (47.8%) in terms of protective efficacy against Xoo in vivo. Meanwhile, some of title compounds also displayed inhibitory effects against phytopathogenic fungi. In a word, this study illustrated that the structures combined with phenylpropane amide derivatives of the acyl hydrazone units could be used as potential antibacterial reagents in the future.