Total antioxidative activity of evening primrose (Oenothera paradoxa) cake extract measured in vitro by liposome model and murine L1210 cells

The antioxidative effects of evening primrose seeds extract were investigated in vitro. The oil-free cake from evening primrose seeds was extracted with two solvents: water and acetone-water (7:3) mixture. There were various contents of phenolic compounds in these extracts (580 and 180 mg/g of acetone-water and water extracts, respectively; expressed in D-catechin). Acetone-water extract was separated into five fractions according to their absorbance readings at 350 nn using a Sephadex LH-20 column. Collected fractions had maximum absorptions of their UV spectra in a broad range between 278 and 286 nm (except fraction 1), which indicated that flavonoids predominated in the phenolic compounds of evening primrose. Absorption at 325 nm for fraction 1 indicated the presence of phenolic acid in that extract. PC (L-alpha-phosphatidylcholine) liposome system and leukemic L1210 murine cells were used to evaluate the antioxidative activity of extracts and their fractions. In these systems the oxidation process was stimulated by addition of AAPH [2,2'-azobis(2-amidinopropane) dihydrochloride]. Extract with acetone:water had the highest antioxidative activity measured by the PC oxidation to PC-OOH (hydroxyperoxidephosphatidylcholine). Also the same extract in the concentration range from 17.5 to 175 ng/mL significantly inhibited peroxidation of cell membranes expressed by TEARS formation in cell cultures.