Objective To investigate the chemical constituents of Urtica cannabina and their hypoglycemic activity in vitro. Methods The compounds were isolated and purified by column chromatography of HPD-600 macroporous resin, silica gel, preparative TLC, and semi-preparative HPLC. Their structures were elucidated by physicochemical properties and spectral analyses. The hypoglycemic activity was evaluated in vitro through their inhibitory effects on α-glucosidase, sucrase, and maltase. Results Twenty compounds were isolated and identified from the 70% ethanol extract of U. cannabina, including cis-p-hydroxycinnamic acid (1), trans-p-hydroxycinnamic acid (2), dimethyl glansreginate (3), kaempferol 3-O-β-D-glucopyranoside (4), caffeic acid (5), chlorogenic acid methyl ester (6), 4-O-feruloylquinic methyl ester (7), hydroxycinnamic acid methyl ester (8), (E)-p-coumaroyl dimethyl malate (9), fraxidin (10), trans-caffeic acid methyl ester (11), trans-caffeic acid ethyl ester (12), 3,4-dihydroxy-acetophenone (13), 4-caffeoylquinic acid (14), 3-O-p-coumaroyl quinic acid methyl ester (15), 3-O-feruloylquinic methyl ester (16), hydroxybenzoic acid (17), phaseic acid (18), 5-O-p-coumaroylquinic methyl ester (19), 5-O-feruloylquinic methyl ester (20). The in vitro activity screening revealed that compounds 5 and 7 exhibited significant inhibitory activity against α-glucosidase, while compounds 5, 6, 11, 12 and 14 displayed considerable inhibitory effects on both sucrase and maltase. Conclusion Compounds 1, 2, 5—12, and 14—20 are phenolic acids, compound 4 is a flavonoid, and compound 13 is a ketophenol. Among these, compounds 3, 7, 9, 10, 13, 15, 16, and 18—20 were isolated from U. cannabina for the first time. Compound 5 demonstrated notable inhibitory activity against all three enzymes, suggesting that it may serve as the core pharmacophoric structure for the hypoglycemic effect. Structure-activity relationship analysis indicated that the catechol structure and the caffeic acid esterification motif collectively constitute the key structural basis for the glycosidase inhibitory activity of these phenolic acids.

Urticaceae  /  Urtica cannabina L.  /  type 2 diabetes mellitus  /  hypoglycemic activity in vitro  /  dimethyl glansreginate  /  4-O-feruloylquinic methyl ester  /  fraxidin  /  phaseic acid