The Capabilities Of Binding To The Estrogen Receptor And The Influence To The Enzyme Activity Of Phenols Belonging To The EDCs

Endocrine Disrupting Chemicals(EDCs) which are widespread in environment related to our life and work, once entering the bodies of animals and human though food chain, can alter the normal function(s) of the endocrine system, including the damage to reproductive, nervous and immune system. Of the EDCs there is one kind of chemical that can stimulate or partly stimulate estrogens though binding to estrogen receptor or affecting the transformation process of cell signals that could act as estrogens, so that it is called Environmental Estrogens. Nonylphenol(NP), Octylphenol(OP),2,4-Dichlorophenol(2,4-DCP) and Bisphenol A(BPA) are the classic ones of the above category among the phenols. In 1998, EPA had established a tiered testing framework system for screening and testing EDCs, as an in vitro screening constitute of this screening system, Estrogen Receptor Binding assay is widely used for its convenience and quick. However, the traditional estrogen receptor binding assay would involve the use of isotope, which could easily lead to the radioactive pollution, as a result, in this paper, a non-radioactive method based on ELISA is attempted to be established. Thus the abilities of binding to the estrogen receptor of four phenolics mentioned above would be tested appling the non-radioactive method, then the potential estrogenic effect of the four phenols will be discussed.In this study a compective ELISA technology is introduced into the classic estrogen receptor binding assay which would always invoves the use of isotope. As this new eatablished method can avoid radioactive pollution as well as improves sensitivity, it could be viewed as an alternate method to screen the potential EDCs. However, without publicity of this new method and with the loss of comparative data between labs, a lot of laboratory research and the study about relavence between different screening methods are desperately needed.The estrogenic activities of the four phenols have been tested applying the new non-radioactive method. The result has showed that the four phenols all have showed estrogenic activities in the testing system, and the rank of their estrogen binding capabilities relative to DES is:BPA> t-OP> NP> 2,4-DCP, which have indicated that BPA have showed the strongest capability of binding to the estrogen receptor, while 2,4-DCP the weakest. The RBA of BPA is 2.1×10-3, which lies in the similar order as t-OP whose RBA is 1.2×10-3, while the RBA of NP is 7.3×10-4 which lies in the similar order as 2,4-DCP whose RBA is 5.3×10-4. Also the the RBAs of four phenols are all 3-4 orders lower than DES. This study also have tested the combind effects of the mixture when the four phenols are mixed in a proportion with equal toxicity or smiliar as in aquatic environment, the mixtures both act in an slightly than additive or antagonistic way.As the widepread distribution of phenolic EDCs and increasingly serious water pollution, an early warning becomes more and more important. In this study, clam (tapes philippinarum) is taken as the studied animal, the response to individual phenolic chemical has been studied by the change of SOD, CAT and GST activities, thus the combined result can estimate phenolic pollution in the water.The result has indicated that the SOD and CAT activities showed a similar and good correlation to NP,2,4-DCP and BPA. The SOD and CAT activities showed a decreasing trend to NP and 2,4-DCP with increasing concentration, while the GST activity showed an increasing trend at low concentration and decreasing trend at high concentration; The SOD and CAT activities showed an increasing trend to BPA at low concentration and decreasing trend at high concentration; while the GST activity showed a decreasing trend with increasing concentration. So it can be seen that the changes of SOD, CAT and GST activities to NP,2,4-DCP and BPA showed an important relationship, consequently the changes of the three enzymes can be combined to analyze the pollution of three phenols. As for OP, the changes of SOD, CAT and GST activities didn't show an obvious relationship, which are not suitable for an indication of OP pollution in the water. As the antioxidant and detoxicated enzyme activities can be affected by many fators, data comparation between laboratory and field is needed to be further exploited.