Design, synthesis and bioactivity of chalcones and its analogues

The Vernohia anthelmintica L.’s extract is one of the most popular Uygur medicines used for vitiligo. It is believed that the chalcone compounds of the plant play an important role in the treatment since they may activate tyrosinase and improve melanin production. In this study, twenty-one chalcones and nine analogues were synthesized in view of three different components of chalcone (A, B ring and α, β-unsaturated carbonyl). After biological evaluation of their activity on tyrosinase in cell-free systems, the result showed that most compounds (except polyhydroxy chalcones) possess activator effect on the tyrosinase, especially for 13a–15a, 20a and 1b, which bearing a comparable activity to the positive control 8-MOP. SAR of these tyrosinase activator was summed up for the first time as well. Finally, compound 13a was found to increase melanin contents and tyrosinase activity 1.75 and 1.3 fold, respectively, compared with that of untreated murine B16 cells at the concentration of 40 μg/mL.