Detecting Phytoestrogens and Mammalian Estrogens in Blackcurrants (Ribes nigrum)

Phytoestrogens are estrogen-like compounds found in various plants. Menopausal women experience various menopausal symptoms due to reduced estrogen secretion. Ingesting phytoestrogens can alleviate these symptoms. Blackcurrant (Ribes nigrum L., Grossulariaceae) is rich in phytochemicals, including anthocyanins. Blackcurrant extract and anthocyanins have phytoestrogenic effects. Furthermore, blackcurrant extract has a stronger phytoestrogenic activity than blackcurrant anthocyanins alone, suggesting that it contains phytoestrogens other than anthocyanins. Therefore, this study explored the components of blackcurrant that exhibit estrogenic activity. Metabolomic analysis revealed that blackcurrant contains phytoestrogens such as naringenin, daidzein, and resveratrol, as well as mammalian estrogens such as estrone and β-estradiol. Ultrasensitive estrogen analysis revealed that blackcurrant extract contains approximately 40.2 pg/g estrone and 24.5 pg/g β-estradiol, corresponding to approximately 100 times the estrogen content of blackcurrant. This study was the first to discover that blackcurrant contains multiple phytoestrogens and mammalian estrogens.