Products of Aqueous Chlorination of 17β-Estradiol and Their Estrogenic Activities

Abstract

To assess the estrogenic activity potentially stemming from 17beta-estradiol (E2) in drinking water, ESI-LC-MS was used to identifythe products of its aqueous chlorination under the following conditions: 50 microg/L E2, 1.46 mg/L sodium hypochlorite, pH 7.5, 25 degrees C. Seven products, including 2,4-dichloro-17beta-estradiol, monochloroestrone, 2,4-dichloroestrone, and the four byproducts such as 4-[2-(2,6-dichloro-3-hydroxyphenyl)ethyl]-7alpha-methyloctahydroinden-5-one (product C in the text) were identified in chlorinated E2 solution. The estrogenic activities of the aqueous chlorinated E2 solution at 10, 30, 60, 120, and 180 min contact 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. All five solutions elicited transcriptional activation induction. The maximal beta-galactosidase activities induced by the chlorinated solution at 10, 30, and 60 min were similar and slightly lower than those before chlorination, while the activities of the chlorinated solution at 120 and 180 min were about 40% of those before chlorination. Finally, 4-chloro-17beta-estradiol (4-chloro-E2) (we failed to synthesize the 2-chloroestrone (2-chloro-E1)), 2,4-dichloro-17beta-estradiol (2,4-dichloro-E2), and 2,4-dichloroestrone (2,4-dichloro-E1) were synthesized, and product C was fractionated by HPLC. It was found that 4-chloro-E2 elicited strong estrogenic activity, at almost the same level as that of estrone (EC50 = 10(2) nM), while 2,4-dichloro-E2 elicited weaker beta-galactosidase activity compared with that of 4-chloro-E2. The EC50 was ca. 10(3) nM. The maximal beta-galactosidase activity for 2,4-dichloro-E1 was lower than that of 2,4-dichloro-E2, while its EC50 was similar to that of 2,4-dichloro-E2. In addition, product C, 4-[2-(2,6-dichloro-3-hydroxyphenyl)ethyl]-7alpha-methyloctahydroinden-5-one, induced high beta-galactosidase activity at the relatively higher concentration of 3.5 x 10(5) nM. On the basis of the dose-response curve of a single byproduct of chlorinated E2, the estrogenic activity at 120 and 180 min appears to be induced mainly by 2,4-dichloro-E2 and 2,4-dichloro-E1.

By-Products Produced by the Reaction of Estrogens with Hypochlorous Acid and their Estrogen Activities

“…Many kinds of chlorinated derivatives produced by the reaction of E2 and hypochlorous acid were detected in the previous report 9) by LC-MS/MS analysis. However, those products were not isolated, and the structures of most of them were not obvious.…”

Treatment and Removal Strategies for Estrogens From Wastewater

“…This was accompanied by the formation of some carcinogenicity and/or mutagenicity and/or estrogenic DBP namely 4-chloro-E2 and 4-chloro-EE2. Therefore it is important to identify the metabolites or products from the reaction of estrogens with available chlorine and their associated estrogenic activities [110,111].…”

Electrolytic removal of 17α‐ethinylestradiol (EE2) in water streams

“…9 The authors add, however, that chlorination dynamics of estrogens under real-life conditions require further investigation, since factors such as pH, temperature, reaction time, chlorine dose, estrogen concentration and total organic carbon (TOC) content also play a role in this reaction. The apparent-second-order rate constant for the chlorination with hypochlorite for EE2 in drinking water was reported to be 112.…”