Flavonol glycosides from the leaves of Eucommia ulmoides O. with glycation inhibitory activity.

Eucommia ulmoides leaves have been used as a folk remedy for the treatment of diabetes in Korea. The aim of this study was to isolate and identify the compounds which inhibited advanced glycation end-product formation, one of main molecular mechanisms implicated in diabetic complications. A new flavonol glycoside, quercetin 3-O-alpha-L-arabinopyranosyl-(1-->2)-beta-D-glucopyranoside (1), and known flavonols kaempferol 3-O-beta-D-glucopyranoside (astragalin) (2), quercetin 3-O-beta-D-glucopyranoside (isoquercitrin) (3) were isolated from the leaves of Eucommia ulmoides. These compounds exhibited glycation inhibitory activity comparable to that of aminoguanidine, a known glycation inhibitor. The results suggest that the flavonol glycosides with glycation inhibitory activity could be attributed to the anti-diabetic action of Eucommia ulmoides leaves.