2.5. Measurement of tyrosinase inhibition
The tyrosinase inhibitory activities of the herb extracts were
determined using the spectrophotometric method described by
Zheng et al. (2012). The herb extracts were first dissolved in DMSO
at a concentration of 1 g/l, and then diluted to different concentrations
using DMSO. Subsequently, a 30-l mixture was diluted
with a 0.05-mM sodium phosphate buffer (970 L) in the tubes,
followed by the addition of 100 mg/l L-tyrosine (1 mL), and finally,
350 units per milliliter of a mushroom tyrosinase solution (1 mL);
3 mL ofthis reactionsolution wasmixedby vortexing, andthe initial
absorbance was measured at 490 nm. After incubation for 20 min at
25 ◦C, the final absorbance of the reaction solution was measured
at 490 nm.