Tyrosinase kinetic in the presence of three inhibitory medicinal plants

Abstract

The present study is aimed to study the tyrosinase inhibitory effect and kinetic properties in the presence of aqueous and methanolic extracts from Quercus infectoria, Terminalia chebula and Linum usita-tissimum. Different concentration of the extracts was examined against l-tyrosine oxidation in comparison to kojic acid and their IC50 were calculated by probit analysis. The tyrosinase inhibition kinetics, analyzed by Lineweaver–Burk plots, and the parameters of Km and Vmax for each extract were calculated using the Linweaver- -Burk equation. The results show that the methanolic extracts of Q. infectoria (MEQI) and T. chebula (METC) potentially inhibit mushroom tyrosinase with IC50 values of 3.34 and 3.87 μg/ml respectively in comparison to kojic acid (IC50 value = 1.56 μg/ml). The MEQI and METC exhibited the most Vmax (81.96 and 78.74 μg/ml/min respectively). This activity is comparable with one of kojic acid (Vmax= 103 μg/ml/min ). The MEQI and METC also have shown the lowest value of Ki (0.20 and 0.44 respectively) in comparison to kojic acid (Ki= 0.18). The MEQI and METC would be developed further as a natural source of tyrosinase inhibitors. Key words: Linum usita-tissimum, Quercus infectoria, tyrosinase kinetic, Terminalia chebula