Abstract
One of the urgent tasks in understanding endocrine disruptors (EDs) is to compile a list of suspected substances among the huge number of chemicals by using the screening test method. An in vitro screening test is a more useful tool for primary selection of suspected EDs. We have developed an assay for EDs using the yeast two-hybrid system. The assay is based on the ligand-dependent interaction of two proteins, a hormone receptor and a coactivator, and the hormonal activity is detected by β-galactosidase activity. This assay is a very simple and inexpensive test method with high repeatability to detect the agonist, and it is applicable for the detection of antagonist and active compounds after metabolism. Accordingly, it has been used in more than 40 laboratories in Japan. To date, we have tested the estrogenic activity of more than 500 chemicals including natural substances, medicines, pesticides and industrial chemicals. Sixty-four compounds were evaluated as positive and most of these possessed a common structure: phenol with a hydrophobic moiety at the para-position without bulky groups at the ortho-position. These results are expected to facilitate further risk assessment of chemicals, especially EDs.
