抄録
To clarify the contribution of endocrine-disrupting chemicals (EDCs) to the estrogenicity of environmental water, its XAD-2 resin column-concentrates, as well as steroid hormones, alkylphenols and phytoestrogens were assayed by the yeast two-hybrid system with and without S9mix. Lake water, river water, tap water and sewage treatment water exhibited estrogenicity that was enhanced by S9mix. The strong affinity for the estrogen receptor in yeast was observed with steroid hormones containing the 3-position phenolic and 17-position alcoholic hydroxyl groups, and alkylphenols. Among the estrogens, the magnitude of estrogenicity was in the order of: E2>E1>>E3. The estrogenicity of glucuronide or sulfateconjugated estrogens was less than that of free estrogens. However, the estrogenicity of the conjugates of E1, E2 and E3 was enhanced by S9mix. This suggests that the estrogenicity of environmental water enhanced by the addition of S9mix may be due to the estrogen conjugates in the water. The attenuation of E2's estrogenicity by S9mix was also shown that is predicted to be due to its hydroxylation by P450 induced specifically by phenobarbital. The E2-conjugate may be decomposed by some hydrolase expressed primarily in rat liver.
