Isolation of neolignan and phenolic glycosides from the branches of Viburnum macrocephalum f. keteleeri and their α-glucosidase inhibitory activity

f. , not well explored in the pharmaceutical field, is a tall deciduous shrub and commonly used as folk medicines for the treatment of type 2 diabetes (T2D). In this study, the dried branches of f. were extracted with 95% ethanol and the extract was fractionated on the basis of polarity with ethyl acetate and -butanol. Among the different fractions, the ethyl acetate fraction exhibited the highest -glucosidase inhibitory activity, and its bioassay-guided fractionation led to the isolation and identification of six compounds including a new 8- -4′-neolignan glycoside ( ), categorized as a rare 7-deoxy skeleton, three previously undescribed phenolic glycosides ( ), together with two known secondary metabolites ( , ), which were found for the first time in . Noticeably, compound had almost the same intestinal -glucosidase inhibitory activity as the positive control acarbose.