Constituents From the Flowers of Viburnum macrocephalum f. macrocephalum and Their α ‐Amylase and α ‐Glucosidase Inhibitory Activities

Phytochemical investigation of the flowers of Viburnum macrocephalum f. macrocephalum (VMM), a sterile horticultural form native to China, led to the isolation of two new cadinane‐type sesquiterpenes, viburetones A ( 1 ) and B ( 2 ), together with fifteen known compounds ( 3 – 17 ). Compounds 1 and 2 represent the first examples of this skeletal type from the genus Viburnum . The structures of the new compounds were elucidated by comprehensive analysis of their 1D and 2D NMR, HRESIMS, and ECD data. All isolates were evaluated for their inhibitory activities against α ‐amylase and α ‐glucosidase, key enzymes involved in carbohydrate metabolism. Among them, compound 1 exhibited inhibitory activities against α ‐amylase (IC 50 = 38.20 µM) and α ‐glucosidase (IC 50 = 24.15 µM), comparable to those of acarbose (IC 50 = 39.19 and 25.73 µM, respectively). Molecular docking studies suggested that compound 1 bound to the active sites of both enzymes via hydrogen bonding and hydrophobic interactions.