A comparison of endocrine disruption potential of nonylphenol ethoxylate, vanillin ethoxylate, 4-n-nonylphenol and vanillin in vitro

Ecotoxicol Environ Saf. 2019 Jul 15:175:208-214. doi: 10.1016/j.ecoenv.2019.03.060. Epub 2019 Mar 19.

Abstract

The widely used surfactant nonylphenol ethoxylate (NPEO) and its raw material 4-n-nonylphenol (4-n-NP), as well as its degradation products, are recognized as endocrine disrupting chemicals. The USA Environmental Protection Agency (EPA) released an assessment that looked for safe alternatives to NPEO. Vanillin ethoxylate (VAEO) is a novel substitute for NPEO and is quite similar to NPEO in structure; there is a risk that it has similar endocrine disrupting effects to NPEO. However, their effects on various nuclear hormone receptors have not been thoroughly examined. In this study, the effects of NPEO, VAEO, 4-n-NP and Vanillin on the estrogen receptor α (ERα), androgen receptor (AR), thyroid hormone receptor (TR), retinoic X receptor β (RXRβ) and estrogen-related receptor γ (ERRγ) were determined and compared using a battery of recombined yeast strains expressing β-galactosidase. The results showed that NPEO and 4-n-NP acted as significant antagonists of ER, AR, TR and ERRγ. In addition, 4-n-NP also had antagonistic activity toward RXRβ. Moreover, VAEO was shown to be a very weak antagonist of TR and ERRγ, and Vanillin had no interaction with any nuclear receptors. For the first time, it was found that NPEO had AR, TR and ERRγ antagonistic effects and that 4-n-NP was an antagonist of RXRβ. The in vitro data indicated that NPEO, 4-n-NP and VAEO have the potential to act as endocrine disruptors involving more than one nuclear hormone receptor, but VAEO has much lower endocrine disrupting potential than NPEO. Thus, it is critical to find safe substitutes for NPEO and a substitute of NPEO with structural analogues should be carried out with caution. Furthermore, to look for preferable alternatives for NPEO, more in vivo and in vitro studies of the alternatives concerning endocrine disruption are needed, especially in vitro studies need to involve various target points, not only focus on their effects on ER but also take other nuclear hormone receptor pathways into consideration.

Keywords: 4-n-nonylphenol; Nonylphenol ethoxylate; Nuclear receptors; Two-hybrid yeast; Vanillin; Vanillin ethoxylate.

MeSH terms

  • Benzaldehydes / chemistry
  • Benzaldehydes / toxicity*
  • Dose-Response Relationship, Drug
  • Endocrine Disruptors / chemistry
  • Endocrine Disruptors / toxicity*
  • Estrogen Receptor alpha / antagonists & inhibitors
  • Estrogen Receptor alpha / genetics
  • Ethylene Glycols / chemistry
  • Ethylene Glycols / toxicity*
  • Molecular Structure
  • Phenols / chemistry
  • Phenols / toxicity*
  • Receptors, Androgen / genetics
  • Receptors, Androgen / metabolism
  • Receptors, Cytoplasmic and Nuclear / antagonists & inhibitors*
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Thyroid Hormone / antagonists & inhibitors
  • Receptors, Thyroid Hormone / genetics
  • Retinoid X Receptor beta / antagonists & inhibitors
  • Retinoid X Receptor beta / genetics
  • Two-Hybrid System Techniques

Substances

  • Benzaldehydes
  • Endocrine Disruptors
  • Estrogen Receptor alpha
  • Ethylene Glycols
  • Phenols
  • Receptors, Androgen
  • Receptors, Cytoplasmic and Nuclear
  • Receptors, Thyroid Hormone
  • Retinoid X Receptor beta
  • terics
  • vanillin
  • 4-nonylphenol