New Phenylpropanoids from Sasa quelpaertensis Nakai with Tyrosinase Inhibition Activities

Bioactivity-guided fractionation led to the isolation of two new phenylpropanoids, 3-O-p-coumaroyl-1-(4-hydroxy- 3,5-dimethoxyphenyl)-1-propanone (1) and 3-O-p-coumaroyl-1-(4-hydroxy-3,5-dimethoxyphenyl)-1-O-$\beta$-gulcopyranosylpropanol (2), together with three known compounds, N-p-coumaroylserotonin (3), N-feruloylserotonin (4) and p-coumaric acid (5) from the leaves of Sasa quelpaertensis Nakai. Their structures were elucidated by spectroscopic methods including 1D and 2D-NMR. Compared to arbutin (I$C_{50}$ 0.048 mM) as a control, compounds 3 and 4 exhibited stronger tyrosinase inhibition activities with an I$C_{50}$ values of 0.027 mM and 0.026 mM, respectively. Compounds 1 (I$C_{50}$ 0.055 mM) and 2 (I$C_{50}$ 0.053 mM) also showed strong activities.