An exploration of the estrogen receptor transcription activity of capsaicin analogues via an integrated approach based on in silico prediction and in vitro assays

Abstract

Capsaicin has been considered as an alternative template of dichlorodiphenyl trichloroethane (DDT) in antifouling paint. However, information regarding the estrogenic activity of capsaicin analogues is rather limited in comparison to that of DDT analogues and their metabolites. We here explore the ER transcription activity of selected capsaicin analogues via an integrated approach based on in silico prediction and in vitro assays. Molecular simulation and the agonist/antagonist differential-docking screening identified 6-iodonordihydrocapsaicin (6-I-CPS) as a weak ERα agonist, while anti-estrogenicity was expected for N-arachidonoyldopamine, capsazepine, dihydrocapsaicin, trichostatin A, and capsaicin. On the contrary, the large volume of analogues, such as phorbol 12-phenylacetate 13-acetate 20-homovanillate and phorbol 12,13-dinonanoate 20-homovanillate, cannot fit well with the ER cavity. The result of MVLN assay was in accord with the in silico prediction. 6-I-CPS was demonstrated to induce luciferase gene expression, while the other analogues of relatively small molecular volume reduced luciferase gene expression in MVLN cells, both in the absence and presence of estradiol. This finding suggested that the ER transcription activity of capsaicin analogues is generated at least partly through the ERα-mediated pathway. Moreover, receptor polymorphism analysis indicated that capsaicin analogues may exhibit diverse species selectivity for human beings and marine species. © 2014 Elsevier Ireland Ltd.