Antioxidant and free radical-scavenging properties of ethanolic extracts of defatted borage (Borago ONcinalis L.) seeds

摘要

Borage meal exerted a concentration - dependent antioxidant activity in a meat model system. At 2 /100 (w /w), it inhibited (P ≤ 0.0 5) 2-thiobarbituric acid-reactive substances (TBARS), hexanal and total volatile formation in meat by 26.5, 30.5 and l8.6/100, respec- tively. Antioxidant compounds in the meal were concentrated at optimum extraction conditions (in 52/100 ethanol at 74dej.C for 62 min) predicted by response surface methodology (RSM). The resulting extract inhibited (P ≤0.05) the coupled oxidation of β-carotene and linoleate in a β-carotene-linoleate system. The system containing extract at a level providing 200 ppm phenolics retained 8l/100 of the initial β-carotene after 2 h of assay whereas the control retained only ll/100. Inhibition op ≤ 0.05) of TBARS, hexanal and total volatile formation in a meat system containing 200 ppm extract ranged from 18.9 to 88.3/100, depending upon the concentration being tested. The extract inhibited (P≤0.05) conjugated diene, hexanal and total volatile formation in bulk corn oil (8.3-49.6/100 inhibition) and corn-oil-in water emulsion (5.2-32.2/100 inhibition). Hydrogen peroxide, hydroxyl radical and superoxide radical- scavenging properties of the extract were somewhat less than, but comparable to, those observed for trans-sinapic acid at similar concentrations of phenolics. At 200 ppm, a l00/100 quenching of the hydroxyl radical and superoxide radical was evident. The extract scavenged 29 75/100 of the hydrogen peroxide in assay media after l0 min of assay as compared to 3/100 reduction in the control.