LAUSR

BACKGROUND Succinate dehydrogenase is an important target of fungicides. Succinate dehydrogenase inhibitors have widely been used to combat destructive plant pathogenic fungi because they possess efficient and broad-spectrum antifungal activities and as well as unique mode of action. The research and development of novel SDHIs have been ongoing. RESULTS Thirty-six novel quinolin-2(1H)-one derivatives were designed, synthesized and characterized. The single crystal structure of compound 3c was determined through the X-ray diffraction of single crystals. The bioassay results displayed that most compounds had good antifungal activities at 16 μg/mL against Rhizoctonia cerealis, Erysiphe graminis, Botrytis cinerea, Penicillium italicum and Phytophthora infestans. Compounds 6o, 6p and 6r had better antifungal activities than the commercialized fungicide pyraziflumid against B. cinerea. Their EC50 values were 0.398, 0.513, 0.205, 0.706 μg/mL, respectively. Moreover, the inhibiting activities of the bioactive compounds were tested against SDH. The results indicated that they possessed outstanding activities. Compounds 6o, 6p and 6r also exhibited better inhibiting activities than pyraziflumid against SDH. Their IC50 values were 0.450, 0.672, 0.232, 0.858 μg/mL, respectively. The results of molecular dynamics (MD) simulations indicated that compound 6r displayed stronger affinity to SDH than pyraziflumid. CONCLUSION The results of the present study displayed that quinolin-2(1H)-one could be one scaffold of potential SDHIs and will provide some valuable information for the research and development of new SDHIs. This article is protected by copyright. All rights reserved.