Figure 1.

TYR-inhibition of different RPEs. RPE1 to RPE7 were extracts prepared by the mixture of n-hexane–acetone–water of different proportions. Inhibition of the positive control, KA at 0.94 μM, was 95.1 ± 0.4%. Mean value ± standard deviation was expressed (n = 3). RPE, Rheum palmatum extract; TYR, tyrosinase. * p < 0.05, ** p < 0.01, and *** p < 0.001.