Estrogenic Activity of Ultraviolet Absorbers and the Related Compounds

Abstract

The estrogenic activities of ultraviolet absorbers and their related compounds were investigated using MCF-7 cell proliferation assay. Nine of 33 chemicals (benzophenone, 2,4-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 4-hydroxybenzophenone, 3-(4-methylbenzylidene) camphor, ethyl 2-cyano-3,3-diphenylacrylate (etocrylene) and 2-ethylhexyl-2-cyano-3,3-diphenylacrylate (octocrylene)) were positive compared with the vehicle control. Benzhydrol, ethyl cinnamate and 2,2'-dihydroxy-4-methoxybenzophenone were weakly active. When each xenoestrogen was added to the cells along with ICI 182780, an estrogen receptor (ER) antagonist, the cell growth was reduced according to its doses. Therefore, the cell proliferation was suggested to generate through ER. Most of these chemicals were also positive using CHOOSER assay, a new method of testing estrogenic activity of xenoestrogen. Each xenoestrogen was also confirmed to bind to ERalpha and ERbeta using a human ER competitive binding assay against 17beta-estradiol. The concentration order of the strength of its inhibitory effect using both ERalpha and ERbeta was similar to that of MCF-7 cell proliferation assay, except for benzyl 4-hydroxybenzoate (B4HB). B4HB showed a stronger activity on CHOOSER assay and the competitive binding assay using both ERalpha and ERbeta, although there was no activity observed on MCF-7 cell proliferation assay. Our findings were to detect the estrogenic activity of etocrylene and octocrylene in vitro, in addition to confirming the activities of some ultraviolet absorbers as previously reported.