HPTLC method for the quantification of isoflavones in nutritional supplements of red clover (Trifolium pratenseL.)

Nutritional supplements of red clover (Trifolium pratense L.) have gained an increasing popularity in the western diet as an alternative treatment for menopausal complaints such as hot flashes. These effects are attributed to the present isoflavones with high amounts of formononetin, biochanin A, daidzein, glycitein and genistein. Isoflavones are nonsteroidal compounds, which are also called phytoestrogens because of their weak estrogenic effect. For the identification and quantification of these flavonoids, an HPTLC method was established. Chromatography was performed on silica gel HPTLC glass plates with dichloromethane-glacial acetic acid-ethyl acetate (12:2:1, v/v) as mobile phase leading to sufficient separation of the components. Consistent results could be achieved and an efficient distinction between different botanical supplements was possible. HPTLC analysis proved to be an inexpensive method for the quality control of red clover-based dietary supplements.