CHEMBL5736133

Tyrosinase Inhibition Assay: A tyrosinase inhibition assay was carried out using the method reported by Jones et al. (2002) Pigment. Cell Res. 15:335. Using this method, the conversion of L-Dopa, a substrate of tyrosinase, into dopachrome is followed by monitoring absorption at 450 nm. Tyrosinase was prepared in 50 mM potassium phosphate buffer, pH 6.8 (assay buffer) at 2000 U/ml and stored at −20° C. in 1 ml aliquots prior to use. For use in assays, stock enzyme solutions were thawed and diluted to 200 U/ml with assay buffer. A 2 mM working solution of substrate, L-DOPA, was prepared in assay buffer for each assay. Samples were dissolved in 10% DMSO (0.5 ml) and diluted to 5 ml with assay buffer. The reaction mixture consisted of 0.050 ml 2 mM L-DOPA, 0.050 ml 200 U/ml mushroom tyrosinase and 0.050 ml inhibitor. Reaction volume was adjusted to 200 μl with assay buffer. Assays were performed in 96 well Falcon 3097 flat-bottom microtiter plates (Beckton Dickinson, N.J.). Appearance of dopachrome was measured with a WALLAC 1420 Multilable Counter (Turku, Finland). Average velocity was determined from linear enzyme rate as measured by change in absorbance (ΔA450) at 450 nm per minute.