Binding of alkylphenols and alkylated non-phenolics to the rainbow trout ( Oncorhynchus mykiss) plasma sex steroid-binding protein

• Published in: Ecotoxicology and environmental safety 2007-09, Vol.68 (1), p.40-48
• Main Author: Tollefsen, K.-E.
• Format: Article
• Language: English
• Subjects: Agnatha. Pisces; Alkylation; Animal, plant and microbial ecology; Animals; Applied ecology; Binding Sites; Biological and medical sciences; Brackish; Butylphenol; Ecotoxicology, biological effects of pollution; Endocrine disrupter; Endocrine Disruptors - chemistry; Endocrine Disruptors - metabolism; Female; Fish; Freshwater; Fundamental and applied biological sciences. Psychology; General aspects; Marine; Nonylphenol; Octylphenol; Oncorhynchus mykiss; Oncorhynchus mykiss - physiology; Phenols - chemistry; Phenols - metabolism; Protein Binding; SBP; Sex hormone-binding globulin; Sex Hormone-Binding Globulin - metabolism; SHBG; Structure-Activity Relationship; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; Water Pollutants, Chemical - chemistry; Water Pollutants, Chemical - metabolism; Xenoestrogens
• ISSN: 0147-6513; 1090-2414
• DOI: 10.1016/j.ecoenv.2006.07.002

Alkylphenols are well-known endocrine disrupters, mediating effects through the estrogen receptor (ER). Although the estrogenic properties of the alkylphenols are well documented, alternative mechanisms of action are poorly described. In the present work, the interaction of a range of alkyl-substituted phenols and alkyl-substituted non-phenolics with the rainbow trout ( Oncorhynchus mykiss) sex steroid-binding protein (rtSBP) were determined by competitive ligand-binding studies. The role of alkyl chain length and branching, substituent position, number of alkylated groups, and the requirement of a phenolic ring structure were assessed. The results showed that the rtSBP binds to most chemical structures tested, although the highest affinity was obtained for mono-substituted alkylphenols with a chain length of four to eight methyl groups. Interestingly, rtSBP binding was also observed for non-phenolic compounds such as 4- t-butylcyclohexanol and 4- t-butylnitrobenzene suggesting that the rtSBP has a broad binding specificity for alkylphenols and alkylated non-phenolics.