Premium
Stereoisomeric separation and toxicity of the nematicide fosthiazate
Author(s) -
Lin Kunde,
Zhang Feng,
Zhou Shanshan,
Liu Weiping,
Gan Jay,
Pan Zhiyan
Publication year - 2007
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/07-255r.1
Subject(s) - enantiomer , daphnia magna , chemistry , stereoselectivity , elution , carbamate , chiral column chromatography , acute toxicity , chromatography , bioassay , stereoisomerism , toxicity , stereochemistry , organic chemistry , molecule , biology , genetics , catalysis
Considerable attention has been paid to the enantiomeric resolution and toxicity of some chiral organophosphorous pesticides (OPs) with one asymmetric center, but research concerning chiral OPs with two asymmetric centers is still limited. In the present study, the stereoisomeric separation and toxicity of fosthiazate, a chiral OP with two asymmetric centers on phosphorus and carbon atoms, was investigated. All four stereoisomers of fosthiazate were separated successfully with a Chiralpak® AD [amylase tris(3,5‐dimethyl‐phenyl carbamate)] column on high‐performance liquid chromatography. The resolved isomers and the pairs of enantiomers were further distinguished using a circular dichroism detector and an optical rotation detector, designating the first (pk1) and third (pk3) eluted peaks as one pair of enantiomers and the second (pk2) and fourth (pk4) peaks as the other pair. The developed method was used to prepare microquantities of individual stereoisomers that were used for in vitro and in vivo bioassays. The inhibition potencies of the stereoisomers against acetylcholinesterase of Electrophorus electricus were slightly stereoselective, with a maximum difference of 1.4‐fold among the isomers. A 3.1‐fold difference, however, was observed in the acute toxicity of isomers to Daphnia magna. The 48‐h toxicity of isomers to D. magna followed the order pk1 > pk2 > pk4 > racemate ≈ pk3. The stereoselective toxicity to D. magna found in fosthiazate suggests that the environmental safety of fosthiazate should be evaluated on the basis of its individual isomers.