State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China.
State Key Laboratory for Biology of Plant Disease and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, PR China.
J Hazard Mater. 2021 Apr 5;407:124359. doi: 10.1016/j.jhazmat.2020.124359. Epub 2020 Oct 22.
Pyrisoxazole is a chiral fungicide that is routinely applied to agricultural plant protection, but the potential environmental risk may be under- or over-estimated because the risk induced by stereoisomers have never been evaluated individually. Thus, we carried out a systemic evaluation of pyrisoxazole at the stereoisomeric level, including absolute configuration, stereoselective bioactivity, acute toxicity, and stereoselective dissipation behavior. There were 99.0-3545.3 fold difference in bioactivity toward six target pathogens (e.g., Alternaria solani) and 1.3-4.0 times difference in toxicity against aquatic organisms (Selenastrum capricornutum and Daphnia magna) between the best and worst stereoisomer. There appeared to be no significant stereoselective dissipation in all three kinds of soil under aerobic and anaerobic conditions. Stereoselective dissipation in buffer solution and river water only observed between diastereomers rather than between enantiomers. In addition, photolysis played a central role in the dissipation of pyrisoxazole in river water. RS-pyrisoxazole was 2.2- to 6.9-times more bioactive and 1.2- to 2.1-times more toxic than Rac-pyrisoxazole, and what is more, RS-pyrisoxazole degraded faster than other stereoisomers in river water. The result implicated that developing pure RS-pyrisoxazole as commercial product could reduce the input of inactive isomer on the basis of guaranteeing the efficacy against the target pathogens.
吡唑肟是一种手性杀菌剂，常用于农业植物保护，但由于尚未单独评估对映异构体所带来的风险，其潜在的环境风险可能被低估或高估。因此，我们在立体异构体水平上对吡唑肟进行了系统性评价，包括绝对构型、立体选择性生物活性、急性毒性和立体选择性消解行为。在对 6 种靶标病原菌（如茄腐镰孢）的生物活性方面，最好和最差立体异构体之间的差异高达 99.0-3545.3 倍；对水生生物（盐单胞藻和大型溞）的毒性差异高达 1.3-4.0 倍。在有氧和厌氧条件下，所有三种土壤中均未观察到明显的立体选择性消解。在缓冲溶液和河水中仅观察到非对映异构体之间的立体选择性消解，而不是对映异构体之间的立体选择性消解。此外，光解在吡唑肟在河水中的消解中起核心作用。RS-吡唑肟的生物活性比 Rac-吡唑肟高 2.2-6.9 倍，毒性高 1.2-2.1 倍，并且在河水中比其他立体异构体降解得更快。结果表明，在保证对靶标病原菌的防治效果的基础上，开发纯 RS-吡唑肟作为商业产品可以减少无效对映异构体的投入。
