Abstract:

To investigate the antioxidant activities of icariin and icariside Ⅱ,and to clarify the possible antioxidant mechanism.Methods Using Vc and butylated hydroxytoluene (BHT)as  positive controls,the clearance rates  of icariin ,icariside Ⅱ and BHT on 1，1-diphenyl-2-picryl-hydrazyl radical (DPPH?),superoxide anion(O２－?) and hydroxyl free radical (OH?) were measured;the reduction rates of samples were detected by the system of potassium ferricyanide;the  capacities of samples were detected by NADH-NBT-PMS system; the inhibitory rates of lipid peroxidation were detected by thiobarbituric acid (TBA) method;the  total antioxidant activities were determined by bleaching of β-carotene suboleic acid system.Results The samples showed  concentration-dependent scavenging capacities of  DPPH?.The clearance abilities of icariside Ⅱ  were higher than those of  icariin (P<0.05).The clearance effects of  icariin and icariside Ⅱ were concentraion-dependent;compared with the same concentration of BHT,the O2－?  clearance rates of icariside Ⅱ and icariin were slightly lower, and the clearance rate of icariin was much lower than that of icariside Ⅱ.The OH? clearance rates of icariin and icariside Ⅱ  in the concentration of 0.1-0.5 g.L^-1 were (16.76±0.35)% -(40.56±1.46)% and (15.65±0.72)% -(28.51±0.91)%. When the concentration was 0.9 g.L^-1,the inhibitory rates of  lipid peroxidation of icariin,Vc and icariside Ⅱ were  (58.79±1.56)%,(75.05±2.12)% and (37.82±1.43)%.The inhibitory rates no longer changed with the dose increasing.As the sample concentration increasing,the reduction capacities of  icariin,Vc and icariside Ⅱ showed  concentration-dependent tendence.In 30-120 min the  total antioxidant activity of icariside Ⅱ was lower than those of icariin and BHT(P<0.05 or P<0.01).The antioxidant activities of icariin and icariside Ⅱ in vitro  were weaker than those of Vc and BHT.Conclusion Icariin and icariside Ⅱ shows obvious antioxidant activities in  scavenging of DPPH?,O2-? and OH? and inhibition of lipid peroxidation, the total antioxidant activity and the reduction activity.

Key words: icariin, icariside Ⅱ, free radical, lipid peroxidation