Antioxidant activity of a ginger extract (Zingiber officinale)

The antioxidant effect and the total phenols of ginger extract were studied. The total phenols of the alcohol extract were found to be 870.1 mg/g dry extract. 2,2-Diphenyl-1-picril hydrazyl radical (DPPH) scavenging reached 90.1% and exceeded that of butylated hydroxytoluene (BHT), the IC50 concentration for inhibition of DPPH was 0.64 μg/ml. The antioxidant activity in a linoleic acid/water emulsion system determined by means of thiobarbituric acid reactive substances (TBARS) was highest at 37 °C – 73.2%, and 71.6% when the formation of conjugated dienes was inhibited. At 80 °C the antioxidant activity at the highest concentration of a ginger extract was less efficient: 65.7% for conjugated dienes formation and 68.2% for TBARS. The ginger extract inhibited the hydroxyl radicals 79.6% at 37 °C and 74.8% at 80 °C, which showed a higher antioxidant activity than quercetin. The IC50 concentration for inhibiting OH at 37 °C was slower than that at 80 °C – 1.90 and 2.78 μg/ml, respectively. The ginger extract chelated Fe3+ in the solution.