title: Stereoselective Degradation and Transformation Products of a Novel Chiral Insecticide, Paichongding, in Flooded Paddy Soil.
abstract: Paichongding is a chiral neonicotinoid insecticide currently marketed as racemate against sucking and biting insects. Under anaerobic condition, all paichongding stereoisomers underwent appreciable degradation in soil during 100 days of incubation, with estimated t1/2values between 0.18 and 3.15 days. Diastereoselectivity in paichongding degradation was observed, with enantiomers (5S,7R)- and (5R,7S)-paichongding being more preferentially degraded in soils than enantiomers (5R,7R)- and (5S,7S)-paichongding. The half-lives of (5R,7R)- and (5S,7S)-paichongding were 3.05 and 3.15 days, respectively, as compared to 0.18 day for (5R,7S)- and (5S,7R)-paichongding. A total of nine intermediates were identified, of which depropylated paichongding was the predominant metabolite and appeared to be stable and recalcitrant to further degradation. Paichongding is degraded via denitration, depropylation, nitrosylation, demethylation, hydroxylation, and enol-keto tautomerism, producing chiral and biologically active products. These findings could have implications for environmental risk and food safety evaluations.
authors.affiliation: Institute of Nuclear Agricultural Sciences, Zhejiang University , Hangzhou 310029, China.|Shenzhen Key Laboratory of Environmental Chemistry and Ecological Remediation, College of Chemistry and Environmental Engineering, Shenzhen University , Shenzhen 518060, China.
authors.forename: Juying
authors.initials: J
authors.lastname: Li
authors.affiliation: Institute of Nuclear Agricultural Sciences, Zhejiang University , Hangzhou 310029, China.
authors.forename: Sufen
authors.initials: S
authors.lastname: Zhang
authors.affiliation: Institute of Nuclear Agricultural Sciences, Zhejiang University , Hangzhou 310029, China.
authors.forename: Chengchen
authors.initials: C
authors.lastname: Wu
authors.affiliation: School of Pharmacy, East China University of Science and Technology , 130 Meilong Road, Shanghai 200237, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.affiliation: Institute of Nuclear Agricultural Sciences, Zhejiang University , Hangzhou 310029, China.
authors.forename: Haiyan
authors.initials: H
authors.lastname: Wang
authors.affiliation: Institute of Nuclear Agricultural Sciences, Zhejiang University , Hangzhou 310029, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: School of Pharmacy, East China University of Science and Technology , 130 Meilong Road, Shanghai 200237, China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Li
authors.affiliation: Institute of Nuclear Agricultural Sciences, Zhejiang University , Hangzhou 310029, China.
authors.forename: Qingfu
authors.initials: Q
authors.lastname: Ye
mesh_terms: D000693:Anaerobiosis; D053961:Azabicyclo Compounds / Q000737:chemistry* / Q000378:metabolism*; D001673:Biodegradation, Environmental; D002250:Carbon Radioisotopes; D002681:China; D002853:Chromatography, Liquid / Q000379:methods; D055868:Floods; D006207:Half-Life; D007306:Insecticides / Q000737:chemistry / Q000378:metabolism*; D011725:Pyridines / Q000737:chemistry* / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000737:chemistry / Q000378:metabolism*; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D053961:Azabicyclo Compounds; D002250:Carbon Radioisotopes; D007306:Insecticides; D011725:Pyridines; D012987:Soil; D012989:Soil Pollutants; C588015:paichongding
keywords: chiral pesticide; degradation pathway; diastereoselective degradation; paichongding; transformation products