Cranberry (<i>Vaccinium macrocarpon</i>) oligosaccharides decrease biofilm formation by uropathogenic <i>Escherichia coli</i>

The preventive effects of the American cranberry (Vaccinium macrocarpon) against urinary tract infections are supported by extensive studies which have primarily focused on its phenolic constituents. Herein, a phenolic-free carbohydrate fraction (designated cranf1b-F2) was purified from cranberry fruit using ion exchange and size exclusion chromatography. MALDI-TOF-MS analysis revealed that the cranf1b-F2 constituents are predominantly oligosaccharides possessing various degrees of polymerisation and further structural analysis (by GC-MS and NMR) revealed mainly xyloglucan and arabinan residues. In antimicrobial assays, cranf1b-F2 (at 1.25 mg/mL concentration) reduced biofilm production by the uropathogenic Escherichia coli CFT073 strain by over 50% but did not inhibit bacterial growth. Cranf1b-F2 (ranging from 0.625 - 10 mg/mL) also inhibited biofilm formation of the non-pathogenic E. coli MG1655 strain up to 60% in a concentration-dependent manner. These results suggest that cranberry oligosaccharides, in addition to its phenolic constituents, may play a role in its preventive effects against urinary tract infections

Cranberry Xyloglucan Structure and Inhibition of Escherichia coli Adhesion to Epithelial Cells

Cranberry juice has been recognized as a treatment for urinary tract infections on the basis of scientific reports of proanthocyanidin anti-adhesion activity against Escherichia coli as well as from folklore. Xyloglucan oligosaccharides were detected in cranberry juice and the residue remaining following commercial juice extraction that included pectinase maceration of the pulp. A novel xyloglucan was detected through tandem mass spectrometry analysis of an ion at <i>m</i>/<i>z</i> 1055 that was determined to be a branched, three hexose, four pentose oligosaccharide consistent with an arabino-xyloglucan structure. Two-dimensional nuclear magnetic resonance spectroscopy analysis provided through-bond correlations for the α-l-Ara<i>f</i> (1→2) α-d-Xyl<i>p</i> (1→6) β-d-Glc<i>p</i> sequence, proving the S-type cranberry xyloglucan structure. Cranberry xyloglucan-rich fractions inhibited the adhesion of <i>E. coli</i> CFT073 and UTI89 strains to T24 human bladder epithelial cells and that of <i>E. coli</i> O157:H7 to HT29 human colonic epithelial cells. SSGG xyloglucan oligosaccharides represent a new cranberry bioactive component with <i>E. coli</i> anti-adhesion activity and high affinity for type 1 fimbriae