Bacterial surface properties, such as electrostatic potential play an important role in the bacterial adhesion process, which is widely considered as the first step leading to infections. Cranberry juice and its compound A-type proanthocyanidins (PACs) were used to treat two isogenic E. coli strains and human uroepithelial cells and the zeta potentials were measured at several cranberry juice or PACs concentrations. P fimbriae were shown to be slightly positively charged, which helps bacteria adhere onto mammalian cells. PACs significantly decreased the bacterial zeta potentials from -15.6 ± 0.9 mV to -41.5 ± 0.7 mV, which increased the electrostatic repulsion forces to mammalian cells. Cranberry juice treatment did not change bacterial zeta potentials significantly, ranging from -14.9 ± 1.8 mV to -16.3 ± 0.8 mV. The abundance of other compounds in cranberry juice may have blocked the influence of PACs, considering the relatively small proportion of PACs in cranberry juice.

An extract from fresh cranberries was shown to decrease the strength of attachment of Escherichia coli to glass coverslips when incubated together for 2 h. Pre-conditioning of the surface prior to biofilm formation also significantly weakened the strength of attached cells.

BACKGROUND: The inhibition of Escherichia coli growth in the presence of Vaccinium macrocarpon has been extensively described; however, the mechanisms of this activity are not well characterized.

FINDINGS: Here, E. coli was grown in media spiked with cranberry juice. The growth rate and media pH were monitored over more than 300 generations. The pH of the growth media was found to decrease during cell growth. This result was unique to media spiked with cranberry juice and was not reproduced through the addition of sugars, proanthocyanidins, or metal chelators to growth media.

CONCLUSION: This study demonstrated that factors other than sugars or proanthocyanidins in cranberry juice result in acidification of the growth media. Further studies are necessary for a complete understanding of the antimicrobial activity of cranberry products.

An ethanolic extract of Cranberry exerted a significant antimicrobial effect on Saccharomyces bayanus and Pseudomonas fluorescens. The antimicrobial properties of cranberries were due to a number of factors. First, the low pH (2.6) inhibited many microorganisms per se, and its effect on the dissociation of benzoic acid made the inhibition more drastic. Secondly, after raising the pH to 5.2, cranberry juice still did not support the growth of S. bayanus. Growth did occur at pH 5.2 after 0.3% yeast nitrogen base was added. Thirdly, proanthocyanidins and flavonols were found to be the major microbial inhibitors other than benzoic acid. The results showed that proanthocyanidins provided 21.3% of the inhibition, the flavonols 18.5% and benzoic acid 15.6%.

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No abstract - Methods: We tested a 5-fold concentrated preparation of the juice to simulate the cranberry concentrate currently available commercially. The concentrate was diluted 1:1 with trypticase soy broth and adjusted to a pH of 7.0 to ensure that the results would not be confounded by the acidity of the medium. We added an inoculum of approximately 104 colony-forming units per milliliter from an overnight culture of a variety of American Type Culture Collection–quality control strains both to plain broth and the broth to which the cranberry juice had been added. Both cultures were incubated at 35°C and bacterial counts performed in duplicate at 90 minutes and 24 hours.

Periodontitis is a chronic inflammatory disease affecting oral tissues. The continuous, high production of cytokines by host cells triggered by periodontopathogens is thought to be responsible for the destruction of tooth-supporting tissues. Macrophages play a critical role in this host inflammatory response to periodontopathogens. The aim of this study was to investigate the effect of non-dialyzable material prepared from cranberry juice concentrate on the pro-inflammatory cytokine response of macrophages induced by lipopolysaccharides (LPS) from Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum subsp. nucleatum, Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, and Escherichia coli. Interleukin-1 beta (IL-1beta), IL-6, IL-8, tumor necrosis factor alpha (TNF-alpha), and Regulated on Activation Normal T-cell Expressed and Secreted (RANTES) production by macrophages treated with the cranberry fraction prior to stimulation by LPS was evaluated by ELISA. Our results clearly indicate that the cranberry fraction was a potent inhibitor of the pro-inflammatory cytokine and chemokine responses induced by LPS. This suggests that cranberry constituents may offer perspectives for the development of a new therapeutic approach to the prevention and treatment of periodontitis.

Cranberry juice consumption is often used for the treatment of urinary tract infections, but the effect of cranberry juice on heart disease has not been investigated. We evaluated how a cranberry extract containing 1,548 mg gallic acid equivalents/liter (initial pH=2.50) affected low density lipoprotein (LDL) oxidation induced by 10 micromolar cupric sulfate. When LDL oxidation took place in the presence of diluted cranberry extracts, the formation of thiobarbituric acid reactive substances (TBARS) and LDL electrophoretic mobility were reduced. LDL electrophoretic migration was also reduced when the cranberry extract had a pH of 7.00 prior to dilution. This study suggests that cranberry extracts have the ability to inhibit the oxidative modification of LDL particles.

BACKGROUND: Porphyromonas gingivalis is a major aetiological agent of periodontitis, a destructive disease affecting the tooth-supporting tissues. Recent reports have indicated that high-molecular-weight molecules from cranberry juice concentrate can prevent the attachment of human pathogens to host tissues.

OBJECTIVES: The aim of the present study was to investigate the effect of non-dialysable material (NDM) prepared from cranberry juice concentrate on growth, biofilm formation and adherence properties of P. gingivalis.

METHODS: The effect of cranberry NDM on biofilm formation was studied using a polystyrene microplate assay and by scanning electron microscopy. The effect of cranberry NDM on the attachment properties of P. gingivalis was evaluated by a microplate assay in which mammalian proteins were immobilized into wells.

RESULTS: Our results indicated that cranberry NDM is a potent inhibitor of biofilm formation by P. gingivalis. However, it has no effect on growth and viability of bacteria. Cranberry NDM also prevented significantly the attachment of P. gingivalis to surfaces coated with type I collagen, fibrinogen or human serum.

CONCLUSIONS: Our data suggest that cranberry constituents may have a beneficial effect for the prevention and treatment of periodontitis by reducing the capacity of P. gingivalis to colonize periodontal sites.

Dental plaque stability depends on bacterial adhesion to acquired pellicle, and on interspecies adhesion (or coaggregation). A high-molecular-weight cranberry constituent at 0.6 to 2.5 milligrams per milliliter reversed the coaggregation of 49 (58 percent) of 84 coaggregating bacterial pairs tested. It acted preferentially on pairs in which one or both members are gram-negative anaerobes frequently involved in periodontal diseases. Thus, the anticoaggregating cranberry constituent has the potential for altering the subgingival microbiota, resulting in conservative control of gingival and periodontal diseases. However, the high dextrose and fructose content of the commercially available cranberry juice makes it unsuitable for oral hygiene use, and the beneficial effect of the high-molecular-weight constituent requires animal and clinical studies.