A chiral ligand exchange CE system for monitoring inhibitory effect of kojic acid on tyrosinase

A facile chiral ligand exchange capillary electrophoresis (CLE-CE) system with Zn(II)- l -alanine as the chiral selector in the presence of β-cyclodextrin has been developed for enantioseparation of dansyl amino acids . The influence of the key factors, such as buffer pH, the ratio of Zn (II) to ligand, the concentration of β-cyclodextrin and the concentration of the complex, were investigated in detail when d , l -Tyr and d , l -Thr were selected as the model analytes. The proposed method showed favorable quantitative analysis property of dansyl d , l -tyrosine with good linearity ( r 2 ≥0.999) and reproducibility (RSD≤3.8%), then, it was applied in studying the activity of tyrosinase through the determination of l -tyrosine concentration variation after being incubated with the enzyme. Further, the inhibitory efficiency of kojic acid and soy sauce on the tyrosinase was investigated. The IC 50 of kojic acid obtained from the sigmoidal inhibitory curve was 21.35   μM. The results imply that the proposed CLE-CE system has the potential in exploring the activity of enzyme and screening the inhibitors of enzyme.