The Antioxidant And Antityrosinase Activities Of Shikonin

[Objective]: The experiment examined the antioxidant and antityrosina se effects of shikonin.[methods]:The experiment examined the antioxidant effects of shikonin on hydroxyl,superoxide,ABTS,DPPH radical scavenging activity,lipid peroxidation inhibition activity,supercoiled p BR322 plasmid DNA.The experiment also examined the antityrosinase effects,the inhibition type and inhibition constant of shikonin.Molecular docking can predict the binding mode and binding affinity of the tyrosinase and compounds.[result]:The experiment results showed that shikonin has excellent a ntioxidant activity in dose-dependent manner.In the experiment of sc avening hydroxyl,superoxide,ABTS,DPPH radical,and lipid peroxidat ion inhibition activity,the IC50 of shikonin was respectively 16 ?mo l/L,32 ?mol/L,27.27 ?mol/L,80 ?mol/L,and 16.67 ?mol/L.The IC50 of baicalein used as the positive control drug was respectively 12 ?mol/L,16 ?mol/L,9.09 ?mol/L,60 ?mol/L,and 12.5 ?mol/L.Shikonin a nd baicalein exhibited protection supercoiled p BR322 plasmid DNA agai nst free radicalinjury induced by AAPH in a dose-dependent manner.The experiment results showed that shikonin has good antityrosinase activity in dose-dependent manner.The IC50 of shikonin and baicalein was respectively 26.67 ?mol/L,13.33?mol/L.The results exhibited that shikonin was the reversible and competitive-uncompetitive mixed type inhibitor of tyrosinase diphenolase.The values of KI and KIS were determined as 19.0 ? mol/L and 48.6 ? mol/L,respectively.The combination mode and binding sites of tyrosinase and shikonin,baicalein were studied by molecular simulation.The results showed that shikonin and baicalein enter the hydrophobic activity cavity of tyrosinase,change the enzyme conformation,which in turn affect the catalytic activity.The hydrogen bonds between Val 283,His 85 residues and compounds,the pi-pi bonds between Phe 264,His 244,His 259,or His 263 and compounds or pi-alkyl bonds between Val 283,Val 248 and compounds,may be related to the identification and fix the ligand and tyrosinase.Shikonin has two phenolic hydroxyls,while baicalein has three phenolic hydroxyls.The different molecular structures lead to the different antioxidant and antityrosinase activities.[Conclusion]: In a word,shikonin has good antioxidant and antityrosinase activities,which supports the use of shikonin as the new food additives,cosmetic materials,and anti-aging candidate drug.