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

Nonylphenol is present in surface water and aquatic sediments and because o f its lipophilic characteristics shows a considerable potential to bioaccum ulate in aquatic organisms. Nonylphenol inhibits testicular growth and indu ces vitellogenin synthesis in male rainbow trout. In order to better unders tand the effects of nonylphenol on fish and its impact in the aquatic envir onment, it is essential to elucidate the metabolic fate of this compound. A single oral dose (5 mg, 1850 KBq) of [H-3]4-n-nonylphenol resulted in 1.1% and 3.0% of the ingested radioactivity eliminated in urine after 24 and 48 h, respectively. Four metabolites were separated by radio-HPLC and tentati vely identified by mass spectrometry. Urinary metabolites likely resulted f rom the initial omega-oxidation of 4-n-nonylphenol to the putative 9-(4-hyd roxyphenyl)-nonanoic acid which subsequent P-oxidation led to 4-hydroxybenz oic acid as major metabolite. Intermediary metabolites, namely 3-(4-hydroxy phenyl) propionic acid and 3-(4-hydroxyphenyl)-2-propenoic acid confirmed t he occurrence of this p-oxidative pathway. Urinary metabolites identified i n this study were quite different from biotransformation products previousl y described in bile of trout treated with 4-n-nonylphenol. (C) 1999 Elsevie r Science B.V. All rights reserved.