Hydrolyzable tannins from the cores of Cornus officinalis with inhibitory activity in vitro on the formation of advanced glycation end products (AGEs)

Abstract

In an ongoing project directed toward the discovery of novel treatments for diabetic complications from traditional herbal medicines [1–3], five phenolic compounds, 1,2,3-tri-O-galloyl-β-d-glucose (1), 1,2,6-tri-O-galloyl-β-d-glucose (2), 1,2,3,6-tetra-O-galloyl-β-d-glucose (3), gallic acid 4-O-β-d-(6-O-galloyl)-glucoside (4), and gallic acid 4-O-β-d-glucoside (5), as well as five other constituents, β-sitosterol, daucosterol, betulinic acid, ursolic acid, and malic acid, were isolated from an EtOAc-soluble extract of the cores of Cornus officinalis (Cornaceae). The structures of the compounds were identified by physical and spectroscopic methods, as well as by comparison of their data with literature values. All the isolates were evaluated in vitro for inhibitory activity on the formation of advanced glycation end products (AGEs). Of these, the hydrolysable tannins 1-3 exhibited significant AGEs formation inhibitory activity with IC50 values ranging from 1.89 to 2.81µM.