Design, Synthesis, Antifungal and Antibacterial Activities of Novel Difluoromethyl Pyrazole Derivatives

In this study, a series of novel difluoromethyl pyrazole derivatives were synthesized and their structures were confirmed by ¹H NMR, ¹³C NMR, and HRMS techniques. Subsequently, their antifungal activities in vitro against Mucor fragilis (M. fragilis), Trichoderma atroviride (T. atroviride), and Mucor bainieri (M. bainieri) at concentrations of 50 and 100 μg/mL were evaluated using the mycelium growth rate assay. Bioactivity results showed that the target compounds revealed lower antifungal activities against M. fragilis, T. atroviride, and M. bainieri than those of prochloraz and carbendazim. Additionally, the antibacterial activities against Xanthomonas axonopodis pv. citri (Xac) and Xanthomonas oryzae pv. oryzicola (Xoo) were determined using the turbidimeter test method. The bioassay results demonstrated that some of the target compounds exhibited moderate to good antibacterial activities. Notably, 2-methoxyphenyl 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylate displayed superior antibacterial effects against Xoo and Xac with inhibition rates of 62, 86 and 53, 80%, respectively, compared to those of thiodiazole copper.