Chiral resolution of racemic phenylpropanoids with tyrosinase inhibitory activities from the fruits of Crataegus pinnatifida Bge.

Seven pairs of enantiomeric phenylpropanoids (1a/1b-7a/7b), including eight undescribed phenylpropanoids (1a, 2a/2b, 3a, 5a, 6a/6b, and 7b) were found in the fruits of Crataegus pinnatifida Bge. The enantiomers were separated using chiral column and elucidated through various spectroscopic methods and quantum chemical ECD calculations. The tyrosinase inhibitory activity of enantiomers was tested in vitro. Among them, enantiomers 1a/1b displayed moderate tyrosinase inhibitory activities. The interaction patterns were further studied by molecular docking, and the results indicated compounds 1a/1b may bind in the active site near the copper atom and interacted with the hydrophobic areas in the active pocket. PRACTICAL APPLICATIONS: Melanins exist widely in organisms and will be produced more against environmental stresses. Without th enzymatic action of tyrosinase, melanin biosynthesis would be blocked. Thus, tyrosinase inhibitors have been developed to modulate melanin formation. In this study, the enantiomeric phenylpropanoid isolated from the fruits of C. pinnatifida Bge displayed moderate tyrosinase inhibitory activities. This work may provide foundations for further research on tyrosinase inhibitor from natural sources.