Design, Synthesis, and Antifungal Activities of Novel Carboxamides Derivatives Bearing a Chalcone Scaffold as Potential SDHIs
Bo Luo, Chongchong Zhang, Suya Liang, Wei Zhou, Yihan Hu, Yulin Li, Jiayi Hu, Lailiang Qu
Abstract
Abstract In search for SDHIs fungicides, twenty‐five novel carboxamides containing a chalcone scaffold were designed, synthesized, and evaluated for antifungal activities against five pathogenic fungi. The results showed that compound 5 k exhibited outstanding antifungal activity against R. solani with an EC 50 value of 0.20 μg/mL, which was much better than that of commercial SDHIs Boscalid (EC 50 =0.74 μg/mL). Moreover, compound 5 k also displayed promising antifungal activities against S. sclerotiorum , B. cinerea , and A. alternate (IC 50 =2.53–4.06 μg/mL), indicating that 5 k had broad‐spectrum antifungal activity. Additionally, in vivo antifungal activities results showed that 5 k could significantly inhibit the growth of R. solani in rice leaves with good protective efficacy (57.78 %) and curative efficacy (58.45 %) at 100 μg/mL, both of which were much better than those of Boscalid, indicating a promising application prospect. Moreover, SEM analysis showed that compound 5 k could remarkably disrupt the typical structure and morphology of R. solani hyphae. Further SDH enzyme inhibition assay and molecular docking study revealed that lead compound 5 k had a similar mechanism of action as commercial SDHI Boscalid. These results indicated that compound 5 k showed potential as a SDHIs fungicide and deserved further investigation.