ANTIOXIDANT ACTIVITY OF PHENOLIC EXTRACTS OF EVENING PRIMROSE (OENOTHERA-BIENNIS) - A PRELIMINARY-STUDY

Phenolic compounds from ethanolic extracts of evening primrose (Oenoth era biennis) were separated into ten fractions using Sephadex LH-20 co lumn chromatography. For individual fractions, UV spectra were recorde d and the content of total phenolics determined. Antioxidant activity of each isolated fraction was examined in a beta-carotene-linoleate mo del system. Fractions were further characterized for the number of phe nolic compounds, presence of proanthocyanidins and their antioxidant a ctivity by TLC analysis. Strong antioxidant properties were noted for fractions with high content of total phenolics (fractions IV-X). Vanil lin-positive compounds were observed in fractions VI-X and one compoun d was tentatively identified as (+)catechin/(-)epicatechin. From fract ion IV, two phenolic compounds were separated by preparative TLC; comp ound A was most likely an isoflavone and the UV spectrum of compound B was similar to that of 2-hydroxychalcone.