Flavan-3-ols Having a .GAMMA.-Lactam from the Roots of Actinidia arguta Inhibit the Formation of Advanced Glycation End Products in Vitro

Two new flavan-3-ols, 6-(2-pyrrolidinone-5-yl)-(−)-epicatechin (1) and 8-(2-pyrrolidinone-5-yl)-(−)-epicatechin (2), as well as five known compounds, (−)-epicatechin (3), (+)-catechin (4), proanthocyanidin B-4 (5), (+)-pinoresinol, and p-hydroxybenzoic acid, were isolated from an EtOAc-soluble extract of the roots of Actinidia arguta. The structures of compounds 1 and 2 were elucidated by spectroscopic data interpretation, particularly by...