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Products of aqueous chlorination of 4‐nonylphenol and their estrogenic activity
Author(s) -
Hu JianYing,
Xie GuoHong,
Aizawa Takako
Publication year - 2002
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1002/etc.5620211005
Subject(s) - nonylphenol , chemistry , yeast , toxicity , aqueous solution , ic50 , coactivator , chromatography , estrogen receptor , endocrine disruptor , environmental chemistry , biochemistry , in vitro , organic chemistry , biology , cancer , breast cancer , hormone , transcription factor , gene , genetics , endocrine system
Seven reaction products (2‐chloro‐4‐nonylphenol [NP], 2,6‐dichloro‐4‐NP, trichlorophenol, 4‐propyl‐2′‐hydroxyphenol, 4‐isobutyl‐2′‐hydroxyphenol, 4‐isoamyl‐2′‐hydroxyphenol, and 4‐isopentyl‐2′‐hydroxyphenol) were identified by gas chromatography/mass spectrometry (GC/MS) in order to assess the estrogenic activity originated from 4‐nonylphenol (4‐NP) in drinking water. The estrogenic activities of the aqueous chlorinated 4‐NP solution at 10, 60, and 120 min chlorination time were assessed by a yeast two‐hybrid system based on the ligand‐dependent interaction of two proteins, a human estrogen receptor (ER), and a coactivator. It was found that all three solutions inhibited transcriptional activation induction by 4‐NP. Further experiments showed that these solutions also inhibited β‐galactosidase induction by 17β‐estradiol. For the solution at 10 min, the inhibition was found to be due to its toxicity, with an inhibition concentration (IC50) of about 10‐fold of concentration of chlorinated 4‐NP solution, suggesting the existence of some products with higher yeast toxicity than that of the parent 4‐NP. Similar inhibition trends were also found in the dose response of the two solutions at 60 and 120 min, with an IC50 of 10‐fold concentration. In these cases, the effects were considered to result from their antagonist action because the two solutions show lower yeast toxicity of which IC50 is 45‐fold concentration. This suggests that some products in the chlorinated 4‐NP solution elicit the antiestrogenic activities.