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-l-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 mu g/ml. The antioxidant activity in a linoleic acid/water emulsion system determined by means of thiobarbituric acid reactive substances (TBARS) was highest at 37 degrees C - 73.2%, and 71.6% when the formation of conjugated dienes was inhibited. At 80 degrees 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 degrees C and 74.8% at 80 degrees C which showed a higher antioxidant activity than quercetin. The IC50 concentration for inhibiting OH center dot at 37 degrees C was slower than that at 80 degrees C - 1.90 and 2.78 mu g/ml, respectively. The ginger extract chelated Fe3+ in the solution. (c) 2006 Elsevier Ltd. All rights reserved.