A New Isoflavanol from the Fruits of Kotschya strigosa (Fabaceae)

The phytochemical investigation of the MeOH extract from fruits of Kotschya strigosa using repeated normal and reversed-phase column chromatography and Sephadex LH-20 chromatography led to the isolation and characterization of a new isoflavanol, named kotstrigoisoflavanol (1), together with three known compounds, diosmetin (2), beta-sitosterol (3), and the 3-O-beta-D-glucopyranoside of beta-sitosterol (4). The antioxidant activity of crude extract, 1, and 2 was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH.) method. The crude extract (IC50 61.7 +/- 0.2 mu g/ml) and 2 (IC50 70.2 +/- 0.1 mu g/ml) showed moderate antioxidant activities, while 1 was weakly active (IC50 153.1 +/- 0.1 mu g/ml), as compared with the standard reference L-ascorbic acid (IC50 21.9 +/- 0.0 mu g/ml).