Investigation of tyrosinase inhibitory components in Camellia reticulata and the inhibitory mechanism, binding behavior of TeGG to tyrosinase

Camellia reticulata Lindl., an ornamental plant cultivated in Southwest China, was investigated as a potential source of novel natural Tyrosinase inhibitors. Three tannins, 1,2,3,6-tetragalloylglucose (TeGG), procyanidin B2, and procyanidin C1, were identified from the plant extracts as potential active components. Among them, gallotannin TeGG exhibited higher activity than β-arbutin, while its Tyrosinase inhibitory mechanism is unclear. So, the kinetic study and multi-spectroscopic study were applied to elucidate the Tyrosinase inhibitory mechanism of TeGG. As a result, TeGG was suggested as a competitive inhibitor of Tyrosinase and predicted to occupy the channel of Tyrosinase towards its copper catalytic site. The TeGG would not chelate with copper nor change the conformation of Tyrosinase, but bind reversibly to the enzyme, suggesting TeGG and its derivatives are potential Tyrosinase inhibitors, both safe and effective.