Design, synthesis and bioactivity studies of flavonol bio-containing β-amino alcohols

A series of flavonoid derivatives containing β -amino alcohols were designed and synthesized using the natural product flavonols as the lead compounds, and their structures were verified by NMR and HRMS, and the antimicrobial activities of 21 flavonoid derivatives containing β -amino alcohols were systematically evaluated against nine plant pathogenic bacteria. Among the tested compounds, some of them showed good inhibitory effects against Phytophthora capsici ( P.c ), Sclerotinia mycoides ( S.s ), and Phytophthora kiwifruit anopheles ( P.s ). It is noteworthy that compound Y17 exhibited significant inhibitory activity against P.c . At a treatment concentration of 100 µg/mL, Y17 inhibited mycelial growth by 100%, and its half effective concentration (EC ₅₀ ) was 5.2 µg/mL, which was significantly better than that of the azoxystrobin ( Az , 98.4 µg/mL). In addition, at a concentration of 200 µg/mL, the protective (85.7%) and curative (77.8%) effects of Y17 against eggplant fruit blight were significantly higher than those of the Az (42.9% protective and 35.5% curative effects). Scanning electron microscopy (SEM) further confirmed the disruption of bacterial membrane integrity by Y17 . The kinetic simulations showed that Y17 has similarity in nature and energy with the commercial drug Az . Therefore, flavonols derivatives containing β -amino alcohols have a high probability to be used as potential antifungal agents.