A new phenanthropyran, dioscorone B (1), and a new phenanthrene (2), together with seven known compounds (3-9), were isolated from the 75% ethanol extract of Dioscorea septemloba rhizomes. The chemical structures of these compounds were elucidated by comprehensive spectroscopic methods including NMR, HRESIMS, IR, and UV spectra. Compounds 1-5 were first isolated from genus Dioscorea. The proton and carbon chemical shifts of compounds 1-9 were unambiguously assigned based on the 1D-NMR and 2D-NMR data. Compounds 1-5 and 8-9 were first tested for their antioxidant activities. Compounds 1 and 2 showed excellent activities with IC50 values of 0.07 ± 0.10 μM and 0.13 ± 0.09 μM, respectively.
Keywords: Dioscorea septemloba; antioxidant activities; phenanthrene derivative.