Li_2020_J.Agric.Food.Chem_68_7609

Fosthiazate is a widely used chiral organophosphorous nematicide with four stereoisomers. The present study systemically assessed the stereoselectivity of fosthiazate for the first time, including absolute configuration confirmation, stereoselective bioactivity toward nematode and aphid, toxicity to honeybees, and the stereoselective degradation in cucumber and pepper under field conditions. The absolute configurations of the four stereoisomers that eluted on the Superchiral IG-3 column were confirmed as (1S,3R)-(-)-fosthiazate, (1S,3S)-(-)-fosthiazate, (1R,3S)-(+)-fosthiazate, and (1R,3R)-(+)-fosthiazate. Compared with other two stereoisomers, (1S,3R)-fosthiazate and (1S,3S)-fosthiazate possess more than 100 times bioactive and 10 times toxic toward the target and non-target organisms, respectively. The molecular docking found that (1S,3R)-fosthiazate and (1S,3S)-fosthiazate had shorter binding distances and lower energies with acetylcholinesterase (AChE) which illuminated the mechanism of the experimental results. In addition, both the high-bioactive stereoisomers had faster degradation rates in cucumber and pepper. Based on the results of bioactivity, toxicity, and degradation behavior, the stereoisomer mixture of (1S,3R)-fosthiazate and (1S,3S)-fosthiazate will be a better option than the racemic fosthiazate to increase the bioactivity and reduce application dosage.