Abstract
Kojic acid-aromatic aldehydes 6a-6m were synthesized and screened for their anti-tyrosinase activities. These compounds showed potently anti-tyrosinase activity with IC(50) values in the range of 5.32 ± 0.23 to 77.89 ± 3.36 μM compared with kojic acid (IC(50) = 48.05 ± 3.28 μM). Thereinto, compound 6j with 3-fluorine and 4-aldehyde substitutions showed the most potent anti-tyrosinase activity (IC(50) = 5.32 ± 0.23 μM). Enzyme kinetic study revealed that 6j is a noncompetitive tyrosinase inhibitor (Ki = 2.73 μM). The action mechanism of 6j was evaluated by fluorescence spectrum quenching, molecular docking, (1)H NMR titration, etc. The anti-browning assay showed that 6j could delay the enzymatic browning of fresh-cut apples. Besides, the cell viability assay proved that 6j had a good safety profile as an anti-browning agent. Hence, these results identify a new class of anti-tyrosinase and anti-browning agents for further investigation in the food industry.