Research Center of Environmental Science, College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou 310032, China.
J Agric Food Chem. 2012 Jan 11;60(1):160-4. doi: 10.1021/jf203742x. Epub 2011 Dec 23.
The increasing application of chiral pesticides has enhanced interest in their enantioselectivity. However, little relevant information is currently available for enantioselective activity of chiral plant growth regulators. In an attempt to screen active enantiomers of uniconazole, this work investigated enantiomeric separation and the enantioselective effect of uniconazole on the growth of rice seedlings and cyanobacteria. Baseline resolution of uniconazole enantiomers was achieved on a Chiralpak AD column by chiral high-performance liquid chromatography (HPLC). The relationship among circular dichroism (CD), optical rotation (OR), and absolute configuration was successfully established by coupling of CD and OR detection. The t test at the 95% level of confidence indicated significant differences between the enantiomers in their retardant activity toward growth of rice seedlings and stimulation effect on growth of cyanobacteria, the natural biofertilizers in rice paddy fields. The S-(+)-enantiomer was more active than the R-(-)-enantiomer in retarding growth of rice seedlings and stimulating growth of Microcystis aeruginosa . This special enantiomeric selectivity was further elucidated by probing the binding mode of enantiomers to gibberellin (GA) 20-oxidase by molecular docking. The S-(+)-enantiomer was found to bind tightly with GA 20-oxidase. The results suggested that the S-(+)-enantiomer instead of a racemate of uniconazole should be used to improve rice seedling quality.
手性农药的应用日益广泛，人们对手性农药的对映体选择性产生了浓厚的兴趣。然而，目前对于手性植物生长调节剂的对映体选择性活性，相关信息还很少。本研究试图筛选烯效唑的活性对映体，采用手性高效液相色谱法（HPLC）在 Chiralpak AD 柱上实现了烯效唑对映体的基线分离，并通过圆二色（CD）和旋光（OR）检测成功建立了 CD 和 OR 之间的关系。置信水平为 95%的 t 检验表明，烯效唑对水稻幼苗生长的抑制活性和对稻田天然生物肥料蓝藻生长的刺激作用在对映体之间存在显著差异。S-(+)-对映体在手性农药抑制水稻幼苗生长和刺激铜绿微囊藻生长方面比 R-(-)-对映体更具活性。通过分子对接进一步阐明了对映体与赤霉素 20-氧化酶结合模式，阐明了这种特殊的对映体选择性。结果表明，应该使用 S-(+)-对映体而不是烯效唑的外消旋体来提高水稻幼苗的质量。
