Abstract: ObjectiveTo study on the antioxidant activity of salvianolic acids and mechanisms of its protection against DNA antiox idative damage.MethodsFree radical model was employed to investigate the scavenging activity to 1,1-diphenyl-2-picryl-hydrazyl(DPPH)and hydroxyl free radicals.The mechanisms of the effects of salvianolic acids on protection against DNA damage was measured by chemiluminescence on the reaction system of phenanthroline(Phen)-CuSO₄-VC-H₂O₂-DNA.Salvianolic acids composition in samples were determined according to HPLC analysis.ResultsThe hemi-inhibitable concentration(IC₅₀)of crude aqueous extract(AE),ethylacet ate extract(EE),resin extract(RE),ascorbate (VC)and butylated hydroxytoluene(BHT)to DPPH free radicals were 141.2,15.3,14.6,15.8 and 71.5 g/ml.Three extracts could obviously inhibit and delay DNA damage caused by hydroxyl free radicals.The IC₅₀ valvue of chemiluminescence of AE,EE and RE were 1 293.6,62.0,and 49.2 g/ml.The scavenging activity and protective effects against DNA damage were effected by salvianolic acids composition and salvianolic acid B level.ConclusionSalvianic acids can effectively scavenge DPPH and hydroxvl free radicals,protect against DNA damage which belongs to preventive and chain-breaking antioxidants,and the effects are related to salvianolic acid Blevel.