Estrogen receptor alpha (ER-α) antagonistic activity of phytoconstituents from Potentilla atrosanguinea and Potentilla fulgens in breast cancer

The Potentilla genus has long been used traditionally as food and a folklore medicine. In the present study, aerial parts of two Potentilla species, Potentilla fulgens and Potentilla atrosanguinea, of western Himalayan origin, were studied for their anti-breast cancer activity. Ethyl acetate (PAA-EA, PFA-EA), methanolic (PAA-ME, PFA-ME) and hydro-methanolic extract (PAA-HM, PFA-HM) of the plants were tested for their antiproliferative activities against MCF-7 and T-47D breast cancer cell lines. The extracts showed good antiproliferative activity against ER alpha dominant breast cancer cell line T-47D, having IC50 values 6.19 +/- 0.01 to 33.23 +/- 0.04 mu g/ml. Eight compounds were isolated, characterized, and quantified from ethyl acetate and methanolic extracts by column chromatography, 1D, 2D-NMR, HRMS and TLC densitometric analysis. Two compounds (4 and 6) have shown better antiproliferative activity than standard bazedoxifene and were further evaluated for their ER-alpha binding affinity via-fluorescence polarization-based competitive binding assay. The antiestrogenic properties of both compounds were assessed using western blotting. Compounds 4 and 6 were found to have significant affinity for the ER-alpha and managed to decrease its expression by 38 and 54% respectively. Compounds 4 and 6 also had good stability and reactivity as measured by minimal fluctuations in molecular dynamic simulation analysis, a good dock score in molecular docking, and a respectable HOMO-LUMO energy gap in DFT calculations. Compounds 4 and 6 have shown reliable results and can be used in the development of natural product-based anti-breast cancer agents.