Characterization of biliary metabolites of 4-n-nonylphenol in rainbow trout (Oncorhynchus mykiss)

Abstract

1. [R-2,6-³H]-4-n-nonylphenol was synthesized and a single dose (5 mg, 1850 KBq) orally administered to rainbow trout. After 48 h, the radioactivity present in the bile amounted 5.5%. More than ten biliary metabolites were separated by hplc and collected for subsequent mass spectrometry analysis. The metabolic profile was totally modified by β-glucuronidase hydrolysis, showing that most of the metabolites were glucuronic acid conjugates. 2. Conjugated metabolites were identified by lc-ms analysis and their aglycones were analysed by gc-ms analysis as TMS and acetyl derivatives. 3. The major metabolite accounted for 52 ± 11% of the biliary radioactivity and was identified as nonylphenol-glucuronide. 4. Nonylphenol was hydroxylated at both ω and ω-1 positions of the alkyl chain, giving 9-hydroxynonylphenol and 8-hydroxynonylphenol. 5. 9-Hydroxynonylphenolwasoxidized to the corresponding acid,and subsequently β-oxidized, yielding 7-(4-hydroxyphenyl)heptanoic acid, 5-(4-hydroxyphenyl)pentanoic acid, 3-(4-hydroxyphenyl)propionic acid and 3-(4-hydroxyphenyl)-2-propenoic acid.