Abstract: Objective  To detect the ability of gallic acid (GA) to  restore Fe3+ in vitro,and  explore its antioxidant activity in vitro an
d to compare it with recognized antioxidant ascorbic acid (Vc),and to provide experimental basis for antioxident application of GA.
Methods Different concentrations of GA (0.04,0.08,0.12 and 0.16 g/L^-1) and Vc (0.04,0.08,0.12 and 0.16 g/L^-1) were used in the phenant
hroline-Fe2+ system to  occurre Fenton reaction and the potassium ferricyanide-Fe3+ system to occurre Fe3+ restore reaction.The A values of the solution after reaction were detected with  UV spectrophotometer. SPSS 17.0 package and two-way ANOVA were used to analyze the relationship between the A values and concentrations of GA and Vc solution.Results  In the phenanthroline-Fe2+ system，the A value of  GA solution was larger than that of Vc at the same concentration(P<0.05).Compared with 0.04 g/L^-1 GA group,the A values in 0.08，0.12，and 0.16 GA groups were gradually increased(P<0.05);and ethanol influenced the A value of the phenanthroline-Fe2+ system.In potassium ferricyanide-Fe3+ system,the Fe3+ reduction ability of GA was stronger than Vc when their concentrations were  0.04 g?L-1;the abilities were weaker  in the other concentrations.When the concentration of HCl was higher than 0.84× 10－2mol/L^－1,it had  great influence in the A value of potassium ferricyanide-Fe3+ system.Conclusion Compared with Vc,GA has a stronger Fe3+ restoring capacity under certain conditions in vitro.
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Key words: gallic acid, ascorbic acid, phenanthroline-Fe2+ system, potassium ferricyanide-Fe3+ system, spectrophotometric assay