The Synthesis and Antifungal Activity of Nicotinamide Derivatives

Purpose Boscalid is a kind of efficient nicotinamide fungicides, however, which is difficult to be synthesized. This study was to reduce costs and get more compounds with higher bactericidal activity.

Method Seven nicotinamide derivatives were conveniently and efficiently synthesized from commercially available 2-chloronicotinic acid and fluorine-containing aromatic compounds in this study. All the synthesized compounds were characterized by ¹H-NMR, ¹³C-NMR and HRMS spectra. Antifungal activities of the synthesized compounds were evaluated against plant pathogenic fungi Fusarium oxysporum, Botrytis cinerea, Pyricularia oryzae, Rhizoctonia solani and Alternaria solani by an in vitro mycelia growth inhibition assay.

Results All the tested compounds exhibited strong antifungal activity against R. solani and B. cinerea. Furthermore, we found that the inhibition rates of compounds 3a and 3e were more than 90% at dose of 50 μg/mL, with EC₅₀ values of 12.63 and 13.99 μg/mL.

Conclusion 3a and 3e were similar to that of commercial fungicide boscalid (EC₅₀ value of 7.36 μg/mL). Further research needs to identify the mechanism of antifungal action of the two synthesized compounds.