The structure of cranberry proanthocyanidins which inhibit adherence of uropathogenic P-fimbriated Escherichia coli in vitro

Ethyl acetate extracts of Sephadex LH20-purified proanthocyanidins of Ameri can cranberry (Vaccinium macrocarpon Ait.) exhibited potent biological acti vity by inhibiting adherence of uropathogenic isolates of P-fimbriated Esch erichia coli bacteria to cellular surfaces containing alpha-Gal(1 --> 4)bet a-Gal receptor sequences similar to those on epithelial cells in the urinar y tract. The chemical structures of the proanthocyanidins were determined b y C-13 NMR, electrospray mass spectrometry, matrix-assisted laser absorptio n time-of-flight mass spectrometry and by acid catalyzed degradation with p hloroglucinol. The proanthocyanidin molecules consisted predominantly of ep icatechin units with mainly DP of 4 and 5 containing at least one A-type li nkage. The procyanidin A2 was the most common terminating unit occurring ab out four times as frequently as the epicatechin monomer. (C) 2000 Elsevier Science Ltd. All rights reserved.