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

Abstract 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 1D and 2D 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 IC 50 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 EC 50 values of (2.9 ± 0.1) and (5.0 ± 0.1) µmol/L [EC 50 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.