Flavonol glycosides from Eriocaulon buergerianum Körn. and their α-glucosidase inhibitory effects.

A new flavonol glycoside, patuletin 3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside-7-O-β-D-glucopyranoside (1), together with three known flavonol glycosides (2-4) were isolated from Eriocaulon buergerianum Körn. Their structures were illuminated by comprehensive spectral methods and chemical methods. Molecular docking and deep learning studies showed that these compounds have potential α-glucosidase inhibitory activity. Α-glucosidase inhibition assay showed that the IC50 values of four flavonol glycosides (1-4), along with two aglycones, patuletin (5) and quercetin (6), were 205.2, 169.8, 508.5, 547.3, 57.0 and 14.5 μM, respectively. The acid hydrolysis experiment of the aqueous extract indicated that the flavonoids in this plant are mainly flavonol glycosides containing patuletin. Therefore, the flavonoids containing patuletin in this plant may be important constituents for its hypoglycaemic activity.