Estrogenic activity of Bryonia dioica Jacq. through in silico and in vitro studies on pS2 gene expression in the breast cancer cell line MCF-7

Bryonia dioica is a member of the Cucurbitaceae that produces bioactive secondary metabolites (PSM), especially steroidal cucurbitacins. Tubers accumulate cucurbitacins, tetrahydrocucurbitacins, bryonioside, and polyphenols such as kaempferol and isovitexin. Through in vitro and simulation studies, this study explores the potential estrogenic and antiestrogenic properties of Bryonia dioica. In silico study was performed by molecular docking simulation to predict the binding affinity of Bryonia PSM in Estrogen Receptor Alpha using Molegro Virtual Docker ver 6.0. The in vitro investigation of a methanolic tuber extract used MCF-7 cells, a breast cancer cell line with estrogen receptor (ER), in a medium with or without estradiol. We also analyzed the effect of the extract on the expression of the estrogen-dependent pS2 gene using real-time polymerase chain reaction (RT-PCR). Molecular docking showed that Cucurbitacin-E exhibited the best binding affinity to the estrogen receptor with binding sites at His 524, Gly 521, Arg 394, Glu 353, and Leu 391. Methanolic extract of Bryonia dioica exhibited cytotoxic activity in MCF-7 cells with IC50 = 185 µg/mL (in medium without E2) and IC50 = 125 µg/mL (in medium with E2). In media with and without estrogen, it can stimulate the expression of the pS2 gene at a concentration of 50 µg/mL, a marker for estrogenic activity. The results suggest that Bryonia dioica contains phytoestrogenic PSM with ER agonistic and cytotoxic activities.