Two New Coumarins from Fraxinus chinensis Rexb.

Abstract The ethanol extract of the stem bark of Fraxinus chinensis Roxb. showed good inhibitory bioactivity against VEGF receptor‐1 kinase (IC 50 : 13.8 μg/mL). In order to find new and bioactive compounds, the chemical constituents of the stem bark of F. chinensis were investigated and two new coumarins, namely 6′‐O‐sinapinoyl esculin (compound 1) and 6′‐O‐vanillyl esculin (compound 2), together with eleven known compounds (compounds 3–13) were isolated. The structures of the two new compounds were identified by their physicochemical properties and spectral analysis, particularly one‐ and two‐dimensional nuclear magnetic resonance spectral methods. The known compound, oleuropein (compound 11), exhibited moderate activity (IC 50 : (8.7 ± 1.3) μmol/L) to inhibit VEGF receptor‐1 kinase.