Stereoselective degradation and toxic effects of benalaxyl on blood and liver of the Chinese lizard Eremias argus.
Benalaxyl as a xylem-systemic fungicide is usually direct sprayed on the soil surface, which is potential harm to the animals lived in the soil. However, the stereoselectivity of benalaxyl in reptiles have rarely been studied. In this study, Chinese lizards (Eremias argus) were firstly used to evaluate the stereoselectivity in biodegradation and toxicity of racemate and individual enantiomers of benalaxyl. A method for determining residues of the two enantiomers of benalaxyl in lizard blood and liver by high-performance liquid chromatography coupled with triple quadrupole mass spectrometry (HPLC-MS/MS) was developed. The degradation followed pseudo first-order kinetics and the degradation of the (S)-(+)-benalaxyl was faster than its antipode in blood and liver (Half-time t1/2 of (R)-(-)-benalaxyl and (S)-(+)-benalaxyl were 5.08 h and 3.75 h in blood, 6.21 h and 4.45 h in liver, separately). Moreover, antioxidant defenses consisting of activities of superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST) and lipid peroxide malondialdehyde (MDA) were determined in 24h acute exposure. Enantioselectivity of acute toxicity depended on the concentration and form of benalaxyl. In addition, cellular degeneration, decrease of cell number, clustering phenomena of cell nuclei and preliminary liver fibrosis were observed in pathological detection at the termination of 21-d subchronic exposure (20 mg/kg(-bw) of racemate and individual enantiomers of benalaxyl). The enantiomer fractions (EFs) in racemate and individual enantiomer groups were approached both in blood and liver caused by the chiral conversion. The chiral conversion from (R)-(-)-benalaxyl to (S)-(+)-benalaxyl and (S)-(+)-benalaxyl to (R)-(-)-benalaxyl were the primary cause for no remarkable differences in toxicity between the enantiomers of benalaxyl.
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Yinghuan
Y
Wang
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Baoyuan
B
Guo
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Yongxin
Y
Gao
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Peng
P
Xu
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Yanfeng
Y
Zhang
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China.
Jianzhong
J
Li
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, China. Electronic address: huiliwang@rcees.ac.cn.
Huili
H
Wang
D000409:Alanine / Q000031:analogs & derivatives* / Q000097:blood / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D001673:Biodegradation, Environmental; D002374:Catalase / Q000378:metabolism; D005659:Fungicides, Industrial / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D005982:Glutathione Transferase / Q000378:metabolism; D007700:Kinetics; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008116:Lizards / Q000097:blood / Q000378:metabolism*; D008315:Malondialdehyde / Q000378:metabolism; D030162:Reptilian Proteins / Q000378:metabolism; D013237:Stereoisomerism
D005659:Fungicides, Industrial; D030162:Reptilian Proteins; C052866:benalaxyl; D008315:Malondialdehyde; D002374:Catalase; D005982:Glutathione Transferase; D000409:Alanine
Biodegradation; Chiral conversion; Eremias argus; Stereoselectivity; Toxicity