The Luteolinidin and Petunidin 3- O -Glucoside: A Competitive Inhibitor of Tyrosinase.

The enzyme tyrosinase plays a key role in the early stages of melanin biosynthesis. This study evaluated the inhibitory activity of anthocyanidin ( 1 ) and anthocyanins ( 2 - 6 ) on the catalytic reaction. Of the six derivatives examined, 1 - 3 showed inhibitory activity with IC 50 values of 3.7 ± 0.1, 10.3 ± 1.0, and 41.3 ± 3.2 μM, respectively. Based on enzyme kinetics, 1 - 3 were confirmed to be competitive inhibitors with K i values of 2.8, 9.0, and 51.9 μM, respectively. Molecular docking analysis revealed the formation of a binary encounter complex between 1 - 3 and the tyrosinase catalytic site. Luteolinidin ( 1 ) and petunidin 3- O -glucoside ( 2 ) may serve as tyrosinase inhibitors to block melanin production.