Two new diarylheptanoids and a new phenylhexanol derivative from the bulbils of Dioscorea opposita Thunb. and their α-glucosidase inhibitory activity

Two previously undescribed diarylheptanoids, diosniponol E (1) and F (2), and a new phenylhexanol derivative, (rel-2R,4R)-6-(4-hydroxy-3-methoxyphenyl)-hexane-1,2,4-triol (3), together with seven known compounds, were isolated from the bulbils of Dioscorea opposita Thunb.. Their structures were elucidated by HRESIMS and 1D/2D NMR as well as by comparison with the literature, and absolute configurations of compounds 1 and 2 were deduced by comparison of their experimental and calculated electronic circular dichroic (ECD) spectra. All the isolated compounds were evaluated in vitro for their α-glucosidase inhibitory activity. The results indicated that compounds 3 and 7 exhibited inhibitory effect against α-glucosidase with the IC50 values of 16.2 ± 2.2 and 8.7 ± 1.6 μM, respectively. Molecular docking experiments were performed to identify the probable binding mode of compound 7 in the binding sites of α-glucosidase and molecular dynamics simulations were performed to evaluate the stability over time of the main interactions observed in docking experiments.