Phenolic glycoside constituents from Brassica rapa flowers and their ?-glucosidase inhibitory activity

Two new phenolic glycoside compounds (1, 2) and ten known analogues (3?12) have been isolated from the ethanolic extract of Brassica rapa flowers and identified as 2-O-?-d-glucopyranosyl-(1S)-(4-methoxyphenyl)ethylene glycol (1), 2-(4-O-?-d-allopyranosyl)phenyl-ethanol (2), 2-O-?-d-glucopyranosyl-(1S)-phenylethylene glycol (3), 2-O-?-d-glucopyranosyl-(1R)-phenylethylene glycol (4), (Z)-p-coumaryl-O-?-d-glucopyranoside (5), phenyl-O-?-d-glucopyranoside (6), 2-phenylethyl-O-?-d-glucopyranoside (7), salidroside (8), 2-(2-hydroxyphenyl)ethanol-O-?-d-glucopyranoside (9), 4-methoxybenzyl-O-?-d-glucopyranoside (10), 2,4,6-trimethoxyphenyl-1-O-?-d-glucopyranoside (11) and sachaliside 1 (12). The structures of 1 and 2, including absolute configurations, were determined by spectroscopic data (H-1 NMR, C-13 NMR, HSQC, HMBC and ORD) and chemical methods. In addition, most of them exhibited inhibitory activity with IC50 values ranging from 14.43 to 50.20??M in comparison to the positive control acarbose (IC50?=?15.76??M) in intestinal ?-glucosidase inhibitory activity tests.