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

Four flavan-3-ols, (+)-catechin ( 1), (+)-catechin 7- O- beta- D-apiofuranoside ( 2), (+)-catechin 7- O- beta- D-xylopyranoside ( 3), (+)-catechin 7- O- beta- 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 inhibitory 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. AGEs:advanced glycation end products BSA:bovine serum albumin CC:column chromatography CD:circular dichroism.