Bioassay-guided screening and isolation of α-glucosidase and tyrosinase inhibitors from leaves of Morus alba

► Leaves extract of Morus alba exhibited inhibitory activities against α-glucosidase and tyrosinase. ► Bioactive constituents were isolated from extracts by bioassay-guided fractionation. ► One new stable and two pairs of new interconvertible flavanes were isolated. ► Possible scheme for the interconversion was illustrated.