Department of Pesticide Science, College of Plant Protection, State & Local Joint Engineering Research Center of Green Pesticide Invention and Application, Nanjing Agricultural University, Nanjing, China.
Pest Manag Sci. 2021 Jul;77(7):3419-3426. doi: 10.1002/ps.6389. Epub 2021 Apr 18.
Pydiflumetofen, as a new succinate dehydrogenase inhibitor (SDHI) chiral fungicide, has been used in crop production because of its broad-spectrum and high-efficiency antifungal activity. However, little is known about pydiflumetofen at the chiral level. The stereoselective bioactivity and degradation of pydiflumetofen enantiomers were therefore investigated.
Pydiflumetofen presented effective bioactivity against the eight tested phytopathogens, and its enantiomers showed significant differences in activity. The bioactivity of R-pydiflumetofen was 9.0-958.8 times higher than that of the S enantiomer. Treatment with R-pydiflumetofen increased the cell membrane permeability of Sclerotinia sclerotiorum and decreased exopolysaccharide and oxalic acid production more than treatment with S-pydiflumetofen. Furthermore, R-pydflumetofen exhibited better inhibitory activity against the succinate dehydrogenase enzyme of S. sclerotiorum than S-pydiflumetofen by 584-fold. According to homology modeling and molecular docking studies, the binding affinities of the R and S enantiomers were -7.0 and -5.3 kcal mol , respectively. Additionally, the degradation half-lives of S- and R-pydiflumetofen in three vegetables (cucumber, eggplant, and cowpea) under field conditions were 2.56-3.12 days and 2.48-2.76 days, respectively, which reveals that R-pydiflumetofen degrades faster than S-pydiflumetofen.
Based on the results obtained, R-pydiflumetofen not only exhibited a higher bactericidal activity, but also posed fewer residual risks in the environment. The mechanism of the stereoselective bioactivity was correlated with the stereoselective inhibition activity of the target enzyme and affected the cell membrane permeability and the production of exopolysaccharide and oxalic acid. This research could provide a foundation for the systematic evaluation of pydiflumetofen from an enantiomeric view. © 2021 Society of Chemical Industry.
作为一种新型琥珀酸脱氢酶抑制剂（SDHI）手性杀菌剂，吡氟酰草胺因其广谱、高效的抗真菌活性而被应用于作物生产中。然而，目前对于吡氟酰草胺在对映体水平上的了解甚少。因此，本研究考察了吡氟酰草胺对映体的立体选择性生物活性和降解。
吡氟酰草胺对 8 种测试植物病原菌具有有效生物活性，其对映体在活性上表现出显著差异。R-吡氟酰草胺的活性比 S 对映体高 9.0-958.8 倍。与 S-吡氟酰草胺相比，R-吡氟酰草胺处理增加了核盘菌细胞膜的通透性，降低了胞外多糖和草酸的产生。此外，R-吡氟酰草胺对核盘菌琥珀酸脱氢酶的抑制活性比 S-吡氟酰草胺高 584 倍。根据同源建模和分子对接研究，R 和 S 对映体的结合亲和力分别为-7.0 和-5.3 kcal/mol。此外，在田间条件下，S-和 R-吡氟酰草胺在三种蔬菜（黄瓜、茄子和豇豆）中的降解半衰期分别为 2.56-3.12 天和 2.48-2.76 天，这表明 R-吡氟酰草胺比 S-吡氟酰草胺降解更快。
基于研究结果，R-吡氟酰草胺不仅表现出更高的杀菌活性，而且在环境中残留风险较低。立体选择性生物活性的机制与靶标酶的立体选择性抑制活性相关，影响细胞膜通透性以及胞外多糖和草酸的产生。本研究可为从对映体角度系统评价吡氟酰草胺提供依据。 © 2021 英国化学学会。
