α-Glucosidase inhibitors and antioxidants from root bark of Morus alba

Objective: To study the chemical constituents from root bark of Morus alba and their α-glucosidase inhibition and DPPH radical scavenging activities.Methods: The chemical constituents were isolated and purified by repeated column chromatographies on silica gel, Sephadex LH-20, and preparative HPLC. Their structures were elucidated by 1 D and 2 D NMR spectra and HR-ESI-MS.Results: Thirteen compounds 1–13 were isolated and identified. The bioactive assays revealed that compounds 1, 3 and 8 displayed strong α-glucosidase inhibitory activity with IC50 values of(147.1 ± 1.1),(314.1 ± 0.8), and(207.6 ± 0.1) μmol/L, respectively, which were stronger than the positive control of acarbose(418.6 ± 0.1 μmol/L). Compounds 10 and 11 displayed potent DPPH scavenging activity with EC50 values of(2.9 ± 0.1) and(5.0 ± 0.1) μmol/L [EC50 of positive control Vitamin C was(54.8 ± 0.1) μmol/L],respectively.Conclusion: To the best of our knowledge, this is the first report about the compounds 1, 3, and 8 of M.alba with α-glucosidase inhibitory effects.