A-type proanthocyanidin trimers from cranberry that inhibit adherence of uropathogenic P-fimbriated Escherichia coli

Three proanthocyanidin trimers possessing A-type interflavanoid linkages, e picatechin-(4 beta-->6)-epicatechin-(4 beta-->8; 2 beta-->O-->7)-epicatechi n (4), epicatechin-(4 beta-->8, 2 beta-->O-->7)-epicatechin-(4 beta-->8)-ep icatechin (5), and epicatechin (4 beta-->8)-epicatechin-(4 beta-->8, 2 beta -->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 alpha -Gal(1-->4)beta-Gal receptor sequences similar to those on uroepithelial ce lls. The structure of 4 was elucidated by a combination of spectroscopic me thods and acid-catalyzed degradation with phloroglucinol. Also isolated wer e the weakly active epicatechin-(4 beta-->8, 2 beta-->O-->7)-epicatechin (p rocyanidin A2) (3) and the inactive monomer epicatechin (1) and the inactiv e dimer epicatechin-(4 beta-->8)-epicatechin (procyanidin B2) (2).