Flavan-3-ols from Ulmus davidiana var. japonica with inhibitory activity on protein glycation

Four flavan-3-ols, (+)-catechin (1), (+)-catechin 7-O-β-D- apiofuranoside (2), (+)-catechin 7-O-β-D-xylopyranoside (3), (+)-catechin 7-O-β-D-glucopyranoside (4), and proanthocyanidin A-1 (5) as well as three other constituents, isolated from an EtOAc-soluble extract of the stem barks of Ulmus davidiana var. japonica, were evaluated for inhibitory activity against the formation of AGEs. Compounds 1-5 exhibited a significant inhibi-tory activity on the formation of AGEs in an AGEs-BSA assay by specific fluorescence and this was confirmed by an indirect AGEs-ELISA. Moreover, compounds 1 and 5 markedly reduced AGEs-BSA cross-linking to collagen in a dose-dependent manner.