Simple preparation and analysis of a phytoestrogen-rich extract of Pueraria candollei var. mirifica and its in vitro estrogenic activity

Abstract

As a source of phytoestrogens, Pueraria candollei var. mirifica (PM) is popular in phytopharmaceutical product development for estrogen replacement therapy. It is a challenging process to extract a large amount of phytoestrogens from a complex plant mixture and to quantify these compounds for standardization. In this study, the 95 % (v/v) crude ethanol extract of the PM root cortex was reextracted with 0–20 % (v/v) aqueous ethanol. The results from the quantitative analysis showed that 10 % (v/v) ethanol is the lowest solvent ratio that provided a high phytoestrogen content. More than 90 % of the potent phytoestrogens (i.e., deoxymiroestrol and miroestrol) and 80 % of the isoflavonoids (i.e., puerarin, daidzin, daidzein, genistein, and kwakhurin) were distributed into the derived soluble extract. In contrast, the insoluble extract contained a low level of phytoestrogens and was concentrated with less polar unidentified compounds. The extraction efficiency was confirmed by the estrogenic activity of the soluble extract on the proliferation of MCF-7 cells. The results also indicated that deoxymiroestrol mainly contributed to the total proliferative effects of PM, while the antiproliferative or cytotoxic effects occurred from treatment with the insoluble compounds, which were removed by the extraction method. Therefore, this extraction method is helpful to enhance the known phytoestrogen content and simplify the extraction of chemical constituents from PM as an ingredient in healthcare products.