TY - JOUR
T1 - Enzymatic and microbial transformation assays for the evaluation of the environmental fate of diclofenac and its metabolites
AU - Lee, Hyun Jeoung
AU - Lee, Eunhwa
AU - Yoon, Sung Hwa
AU - Chang, Hee Ra
AU - Kim, Kyun
AU - Kwon, Jung Hwan
N1 - Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korean Government (MEST) (No. 2008-0062072). This work was also partially supported by the Post Brain Korea 21 Program.
Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.
PY - 2012/5
Y1 - 2012/5
N2 - Diclofenac has been of environmental concern due to the potential harmful effects on non-target organisms at environmentally relevant concentrations. In this study, we evaluated the transformation kinetics of diclofenac and its two major metabolites in two laboratory-scale experiments: the transformation of diclofenac in the presence of rat liver S9 fraction with co-factors, and the transformation of diclofenac, 4'-hydroxy-diclofenac and diclofenac β- O-acyl glucuronide in the inoculum used for the OECD 301C ready-biodegradability test. 4'-Hydroxy-diclofenac was identified as the major phase I metabolite and diclofenac β- O-acyl glucuronide was identified as the major phase II metabolite in the S9 assay. Transformation of diclofenac in the microbial degradation test did not occur significantly for 28. d, whereas 4'-hydroxy-diclofenac degraded slowly, indicating that the biological removal of diclofenac is not likely to occur in conventional STPs unless sorptive removal is significant. However, diclofenac β- O-acyl glucuronide deconjugated to form equimolar diclofenac within 7. d, in the microbial degradation test. The mixture of diclofenac and its two metabolites, formed after incubating diclofenac in S9 medium for 2. h, was spiked in the inoculum to link both assays. The concentrations of diclofenac and its metabolites, measured over time, agreed well with predicted values, using rate parameters obtained from independent experiments. The results show that phase II metabolites generated in mammals may deconjugate easily in conventional STPs to form a parent compound and that these processes should be considered during the environmental monitoring and risk assessment of diclofenac.
AB - Diclofenac has been of environmental concern due to the potential harmful effects on non-target organisms at environmentally relevant concentrations. In this study, we evaluated the transformation kinetics of diclofenac and its two major metabolites in two laboratory-scale experiments: the transformation of diclofenac in the presence of rat liver S9 fraction with co-factors, and the transformation of diclofenac, 4'-hydroxy-diclofenac and diclofenac β- O-acyl glucuronide in the inoculum used for the OECD 301C ready-biodegradability test. 4'-Hydroxy-diclofenac was identified as the major phase I metabolite and diclofenac β- O-acyl glucuronide was identified as the major phase II metabolite in the S9 assay. Transformation of diclofenac in the microbial degradation test did not occur significantly for 28. d, whereas 4'-hydroxy-diclofenac degraded slowly, indicating that the biological removal of diclofenac is not likely to occur in conventional STPs unless sorptive removal is significant. However, diclofenac β- O-acyl glucuronide deconjugated to form equimolar diclofenac within 7. d, in the microbial degradation test. The mixture of diclofenac and its two metabolites, formed after incubating diclofenac in S9 medium for 2. h, was spiked in the inoculum to link both assays. The concentrations of diclofenac and its metabolites, measured over time, agreed well with predicted values, using rate parameters obtained from independent experiments. The results show that phase II metabolites generated in mammals may deconjugate easily in conventional STPs to form a parent compound and that these processes should be considered during the environmental monitoring and risk assessment of diclofenac.
KW - Environmental fate
KW - Removal efficiency
KW - Risk assessment
KW - Sewage treatment plant
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U2 - 10.1016/j.chemosphere.2012.02.018
DO - 10.1016/j.chemosphere.2012.02.018
M3 - Article
C2 - 22401746
AN - SCOPUS:84862789060
SN - 0045-6535
VL - 87
SP - 969
EP - 974
JO - Chemosphere
JF - Chemosphere
IS - 8
ER -