Effects of an aglycone-rich biotransformed soybean extract in human endothelial cells

Estrogen replacement therapy is not thought to be a safe treatment for prevention of cardiovascular disease in menopausal women; isoflavones are a possible alternative. Estrogen produces beneficial effects on the cardiovascular system by enhancing production of nitric oxide, a vasoprotective and antiatherosclerotic agent. Estrogen-like compounds such as isoflavones are also suggested for increasing nitric oxide production. Isoflavones are present mainly in soy foods as glucosides, but soy isoflavone aglycones, the biologically active estrogen-like compounds, are absorbed faster and in higher amounts than their glucoside derivatives and show higher biological activity, implying that they may be more effective in preventing chronic diseases such as coronary heart disease. We evaluated an extract of soybeans fermented by Aspergillus awamori on which polyphenol glucosides were biotransformed to aglycone forms on production of nitric oxide, prostaglandin E2 and endothelin-1 in vitro in human endothelial cells, comparing it with a non-fermented extract. Bioconverted soybean extracts enhanced endothelin-1, nitric oxide and prostaglandin E2 production, while the unfermented extract only enhanced endothelin-1 production. Thus, only the aglycone-rich forms of soybean extracts were able to increase nitric oxide and prostaglandin E2 production, demonstrating that, in endothelial cells in vitro, they may be usable as therapeutic agents against the development of atherosclerosis.