Effect Of Cyclodextrins On The Enantioselective Inhibition Between Isomalathion And Acetylcholinesterase

Cyclodextrins possess particular configuration and chiral recognition ability,so they may have an anisomerous impact on the different isomers of chiral pesticides.In an attempt to evaluate the enantioselective inhibition of acetylcholinesterase(AChE)by malathion,malaoxon and isomalathion,the half inhibition concentration(IC₅₀)of enantiomers of chiral insecticides was tested in this work.The results revealed that the IC₅₀of S-malathion was a 4.3-fold larger than that of R-malathion for AChE.The IC₅₀of RS-malathion was between that of R and S forms.Similarly,the toxicity of R-malaoxon was a 1.5-fold stronger than that of S-malathion,but the toxicity of RS-malathion was weaker than that of both of them.The inhibitory potency of individual enantiomer of isomalathion for AChE decreased in the order of(1S,3R)-isomalathion＞(1S,3S)-isomalathion＞(1R,3S)-isomalathion＞(1R,3R)-isomalathion.The inhibitory potency of rac-isomalathion was stronger than that of(1R,3R)-isomalathion,but weaker than that of(1S,3R)-isomalathion.The effects of CD on the enantioselective inhibition between isomalathion and AChE were also studied in this work.In the selected concentration range ofα-CD concentration,the enantioselectivity between (1R,3R)-isomalathion and(1S,3S)-isomalathion firstly increased with the increase of theα-CD concentration,then reduced to some value and kept invariable.But to the couple enantiomers of(1S,3R)-isomalathion and (1R,3S)-isomalathion,the variety trend of enantioselectivity was decreasing firstly and then increasing.The variety trend of enantioselectivity between (1R,3R)-isomalathion and(1S,3S)-isomalathion was slowly reducing to nadir at first and then increasing quickly in the studied range ofβ-CD concentration,and the nadir was in the range ofβ-CD concentration between 1 g/L and 1.2 g/L.The variety trend of enantioselectivity between (1S,3R)-isomalathion and(1R,3S)-isomalathion was gently variable withβ-CD concentration ranged from 0.3 g/L to 1.5 g/L.The enantioselectivity between(1R,3R)-isomalathion and(1S,3S)-isomalathion was slowly reducing to nadir at first and then increasing slowly with the increase of the MCD concentration,the nadir occurred near the MCD concentration of 2.5g/L.The variety trend of enantioselectivity between (1S,3R)-isomalathion and(1R,3S)-isomalathion was decreasing firstly and then increasing with MCD concentration ranged from 1.5 g/L to 3.0 g/L. Among the selected three type of CDs,the impacts of all CDs on the enantioselectivity between(1R,3R)-isomalathion and(1S,3S)-isomalathion were bigger than that of all CDs on the enantioselectivity that between (1S,3R)-isomalathion and(1R,3S)-isomalathion.The study indicated that the impact of CD on the enantionselective inhibition for AChE by isomalathion was related with concentrations and type of CDs.This might be ascribe to the different chiral recognition ability of different CDs and the enantionselective recognition between the CDs and isomalathion related with concentration of CDs.This work revealed that the impacts of the CD types,CD concentrations,the proportion of isomers and enantioselective activity should be considered in the practice of using CD as the remediation agents to chiral pesticides contamination or the additive in the preparation of chiral pesticides.The enantionselectivity of chiral pesticides could be regulated by adding CD with different type and different concentration,so CDs might be used to adjust enantionselectivity to meet the need of the environmental safe and the human health.