Lignan Constituents from the Fruits of <i>Viburnum macrocephalum</i> f. <i>keteleeri</i> and Their α-Amylase, α-Glucosidase, and Protein Tyrosine Phosphatase 1B Inhibitory Activities
Chun‐Chao Zhao, Jia Chen, Jian‐Hua Shao, Zhang Xiao-hui, Wen-Yan Gu, Jie Shen, Yang Liu
Abstract
Eight previously undescribed lignan glycosides, viburmacrosides A–H (1–8), and seven known analogues (9–15) were isolated from Viburnum macrocephalum f. keteleeri fruits through bioactivity-guided fractionation. Their structures and absolute configurations were elucidated by extensive spectroscopic analyses and chemical evidence. Using the well-recognized carbohydrate-hydrolyzing enzymes α-amylase and α-glucosidase, as well as the promising protein tyrosine phosphatase 1B (PTP1B), as inhibitory targets, all isolated compounds were tested for their antidiabetic potential in vitro. Compound 4 displayed potent inhibitory activities with IC50 values of 9.9 ± 0.6 and 8.9 ± 0.5 μM against α-glucosidase and PTP1B, respectively. The enzymatic kinetics results suggested that compound 4 competitively inhibited α-glucosidase while it suppressed α-amylase and PTP1B in the mixed-type manner. These findings supported that V. macrocephalum f. keteleeri fruits may be a new functional food resource with antidiabetic potential.