Separation and toxicity of enantiomers of organophosphorus insecticide leptophos.
Enantiomers of leptophos were separated by high-performance liquid chromatography with a Whelk-O1 column using 3% dichloromethane in n-hexane as mobile phase. Toxicity tests of leptophos enantiomers and racemate were performed with daphnia. Enzyme inhibition of leptohpos was carried out by using butyryl cholinesterase from horse serum and acetylcholinesterase from housefly heads. From the inhibition test of butyrylcholinesterase, the half-inhibitory concentrations, IC(50), of (+)-leptophos, (-)-leptophos, and (+/-)-leptophos were 0.241, 1.17, and 1.05 gmL(-1), respectively. No significant difference in IC(50) in (-)-leptophos and (+/-)- leptophos was found. However, the IC(50) of (+)-leptophos was significantly different from those of the others. In the inhibition test of acetylcholinesterase, the IC(50) values of (+)-leptophos, (-)-leptophos, and (+/-)-leptophos were 14.01, 24.32, and 13.22 gmL(-1), respectively. There was no significant difference in IC(50) in (+)-leptophos and (+/-)-leptophos, although the IC(50) of (-)-leptophos was significantly different from those of the others. From these results, leptophos-both enantiomers and racemate-seems to have higher neurotoxicity for mammals than for the target insects. In the toxicity test of daphnia, the half-lethal concentrations, LC(50), of (+)-leptophos, (-)-leptophos, and (+/-)-leptophos were 0.0387, 0.802, and 0.0409 gL(-1), respectively. There is no significant difference in LC(50) in (+)-leptophos and (+/-)-leptophos. The LC(50) of (-)-leptophos is significantly higher than those of the others. From these results, (-)-leptophos has lower toxicity to daphnia.
Yen
Jui-Hung
JH
Department of Agricultural Chemistry, National Taiwan University, 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan. sonny@ccms.ntu.edu.tw
Tsai
Chia Chun
CC
Wang
Yei Shung
YS
D000110:Acetylcholinesterase / Q000378:metabolism; D000465:Algorithms; D000818:Animals; D002091:Butyrylcholinesterase / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003621:Daphnia / Q000502:physiology*; D007306:Insecticides / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*; D010773:Leptophos / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity*; D007928:Lethal Dose 50; D013237:Stereoisomerism
D007306:Insecticides; D010773:Leptophos; D000110:Acetylcholinesterase; D002091:Butyrylcholinesterase