A-Type Proanthocyanidin Trimers from Cranberry that Inhibit Adherence of Uropathogenic P-Fimbriated Escherichia coli

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Abstract
Three proanthocyanidin trimers possessing A-type interflavanoid linkages, epicatechin-(4β→6)-epicatechin-(4β→8, 2β→O→7)-epicatechin (4), epicatechin-(4β→8, 2β→O→7)-epicatechin-(4β→8)-epicatechin (5), and epicatechin-(4β→8)-epicatechin-(4β→8, 2β→O→7)-epicatechin (6), were isolated from the ripe fruits of Vaccinium macrocarpon (cranberry) and prevented adherence of P-fimbriated Escherichia coli isolates from the urinary tract to cellular surfaces containing α-Gal(1→4)β-Gal receptor sequences similar to those on uroepithelial cells. The structure of 4 was elucidated by a combination of spectroscopic methods and acid-catalyzed degradation with phloroglucinol. Also isolated were the weakly active epicatechin-(4β→8, 2β→O→7)-epicatechin (procyanidin A2) (3) and the inactive monomer epicatechin (1) and the inactive dimer epicatechin-(4β→8)-epicatechin (procyanidin B2) (2).