Insecticidal and α-glucosidase inhibitory activities of chemical constituents from Viburnum fordiae Hance.

The ethanolic extract of the stems of Viburnum fordiae Hance showed insecticidal and α-glucosidase inhibitory activities and then was fractionated by bioactivity-guided fractionation to obtain a rare C13-norisoprenoid (1), together with a new phenolic glycoside (2), and seven known compounds, alangionoside C (3), pisumionoside (4), koaburaside (5), 3,5-dimethoxy-benzyl alcohol 4-O-β-d-glucopyranoside (6), 3,4,5-trimethoxybenzyl-β-d-glucopyranoside (7), arbutin (8), and salidroside (9). The previously undescribed compounds were elucidated as (3R,9R)-3-hydroxy-7,8-didehydro-β-ionyl 9-O-α-d-arabinopyranosyl-(1→6)-β-d-glucopyranoside (1) and 2-(4-O-β-d-glucopyranosyl)syringylpropane-1,3-diol (2) by spectroscopic data (1H and 13C NMR, HSQC, HMBC, 1H-1H COSY, HSQC-TOCSY, HRESIMS, IR and ORD) and chemical methods. Compound 1 showed potent insecticidal effect against Mythimna separata with LD50 value of 140 μg g-1. Compounds 2, 5, 6, 8 and 9 showed varying α-glucosidase inhibitory activity with IC50 values ranging from 148.2 to 230.9 μM.