Aryltetralin Lignan Glycosides From the Leaves of <i>Viburnum cylindricum</i> and Their Enzyme Inhibitory Activity

Viburnum cylindricum Buch. -Ham. ex D. Don is a commonly used medicinal Viburnum species containing abundant bioactive secondary metabolites. In this study, 14 aryltetralin lignan glycosides, including three previously undescribed ones, viburindrosides A-C (1-3), along with two rare variable 9-O-2'-aryltetralin lignan glycosides (13 and 14), were isolated from V. cylindricum leaves by utilizing a liquid chromatography-tandem mass spectrometry-guided strategy. The structures of these compounds were elucidated by spectroscopic data, experimental and calculated electronic circular dichroism spectra, and chemical methods. In addition, the activity assessment results indicated that among all isolates, compounds 13 and 14 exhibited the strongest α-glucosidase inhibitory activity with the half-maximal inhibitory concentration (IC₅₀) values of 7.69 and 7.25 µM, respectively, while compounds 5 and 7 showed the potent urease inhibitory activity with the IC₅₀ values of 16.01 and 15.23 µM, respectively. Furthermore, molecular docking studies provided insights into the binding interactions of the four active compounds with α-glucosidase and urease, respectively.