Tyrosinase inhibitory activity of propolis from Jeju Island, Korea.

Propolis is a resinous substance collected by honeybees from the buds and bark of certain trees and plants and is stored in hives. Our previous studies have shown that the major components of propolis from Jeju Island, Korea, are chalcone and coumarin analogs. In this study, we aimed to elucidate the functional properties of propolis obtained from Jeju Island. Propolis extracts from Jeju Island and their main compounds were tested for their tyrosinase inhibitory activity. A 70% ethanol extract of the propolis from Jeju Island and its main component, xanthoangelol (7), showed strong tyrosinase inhibitory activity. Compound 7 showed competitive inhibition against tyrosinase. The predicted structure of the tyrosinase-7 complex showed the same binding sites for 7 and tyrosine, thereby supporting competitive inhibition. Our results indicate that propolis from Jeju Island has the potential to be used as an antibrowning food additive.