Detecting phytoestrogens and mammalian estrogens in blackcurrants (Ribes nigrum L.)

Abstract Phytoestrogens are estrogen-like molecules found in various plants. Menopausal women experience various menopausal symptoms due to reduced estrogen secretion. The ingestion of phytoestrogens is known to alleviate these symptoms. Blackcurrant (Ribes nigrum L.) is a fruit rich in phytochemicals, including anthocyanins. Blackcurrant extract (BCE) and anthocyanins have phytoestrogenic effects. Although BCE has stronger phytoestrogenic activity than blackcurrant anthocyanins, this aspect has not been explored. BCE likely contains phytoestrogens other than anthocyanins. In this study, the components of blackcurrant fruits were comprehensively investigated through metabolome analysis. In addition to phytoestrogens, such as naringenin, daizein, and resveratrol, mammalian estrogens, such as estrone and β-estradiol, were detected in blackcurrant fruits. An ultrasensitive estrogen measurement analysis revealed that BCE contains approximately 40.2 and 24.5 pg/g of estrone and β-estradiol, respectively, corresponding to approximately 100 times the estrogen content in blackcurrant fruits. We report for the first time that blackcurrant contains phytoestrogens and mammalian estrogens.