Figure 2: Analysis of constituents of VVC responsible for the inhibition of human TYR activity. VVC extract was tested against human TYR activity at different concentrations (a). VVC extract was separated into four different solvent fractions and tested against human TYR activity at 10 µg mL−1 (b). The EtOAc fraction was further separated into 11 subfractions by preparatory TLC (c) and tested against human TYR activity (d). The major band in number 5 fraction was presumed to be an active constituent and denoted compound X. Data are presented as percentages of uninhibited activities (means ± SE, ). versus vehicle control.