Quantitative determination of isoflavones by HPLC-UV method and antioxidant activity of trifolium longidentatum

Abstract

In this study, aerial parts of Trifolium longidentatum Nábělek (Fabaceae) were quantitatively analyzed for their content of four isoflavones, daidzein (D), genistein (G), formononetin (F) and biochanin A (B), by the use of developed RP-HPLC-UV method. The chromatographic separation was performed using a gradient system with a mobile phase of methanol, acetate buffer (pH=4.75) and acetonitrile with on the reversed phase column, Agilent Eclipse XDB-18 (15 cm × 4.6 mm i.d.). The contents of D, G, F and B in the aerial parts of T. longidentatum were determined as 0.0095, 0.0056, 0.0021 and 0.0073 %, respectively. Antioxidant potential of the methanol extract prepared from the aerial parts of the plant was also investigated with different in vitro methods, namely DPPH radical scavenging activity, lipid peroxidation inhibition and trolox equivalent antioxidant capacity assays. As a consequence, it was observed that the methanol extract of T. longidentatum had in vitro antioxidant activities in these methods. The phenolic content of the extract was also measured as 53.98 ± 0.95 mg gallic acid/g extract by the Folin-Ciocalteu's reagent.