Abstract: OBJECTIVE: To determine effects of cranberry extract on development of urinary tract infection (UTI) in dogs and on adherence of Escherichia coli to Madin-Darby canine kidney (MDCK) cells. ANIMALS: 12 client-owned dogs (in vivo experiment) and 6 client-owned dogs (in vitro experiment). PROCEDURES: 12 dogs with a history of recurrent UTI received an antimicrobial (n=6) or cranberry extract (6) orally for 6 months. Dogs were monitored for a UTI. For the in vitro experiment, cranberry extract was orally administered to 6 dogs for 60 days. Voided urine samples were collected from each dog before and 30 and 60 days after onset of extract administration. Urine was evaluated by use of a bacteriostasis assay. An antiadhesion assay and microscopic examination were used to determine inhibition of bacterial adherence to MDCK cells. RESULTS: None of the 12 dogs developed a UTI. The bacteriostasis assay revealed no zone of inhibition for any urine samples. Bacterial adhesion was significantly reduced after culture with urine samples obtained at 30 and 60 days, compared with results for urine samples obtained before extract administration. Microscopic examination revealed that bacterial adherence to MDCK cells was significantly reduced after culture with urine samples obtained at 30 and 60 days, compared with results after culture with urine samples obtained before extract administration. CONCLUSIONS AND CLINICAL RELEVANCE: Oral administration of cranberry extract prevented development of a UTI and prevented E. coli adherence to MDCK cells, which may indicate it has benefit for preventing UTIs in dogs.
Abstract: The objective of this study was to determine the in-vitro and in-vivo activity of cranberry extracts against Escherichia coli O157:H7. This strain of E. coli was the most common etiologic agent of urinary tract infections isolated from patients. Filter sterilized aqueous and methanol extract of cranberry was prepared and used in the present study. The aqueous extract of cranberry produced inhibition zone ranging from (10.8-23.8) mm against the tested bacteria. While the methanol extract produces larger zones of inhibition (12.1-24.2) mm against the bacteria. The minimum inhibitory concentration (MIC) for the methanol and aqueous extract was 0.35 and 0.625 mg/ml, respectively. In vivo study involved inducing UTI in rats and then treated with (200 mg/kg B.W) aqueous and methanol extract and compared with Gentamicin treatment at a dose of (2 mg/kg B.W) subcutaneously for 14 days. Methanol extract succeeded in treated UTI caused by Escherichia coli in the infected rats and prevented infection comparing with aqueous extract and Gentamicin. Food, water intake, body weight, pH and creatinine level returned to normal values after treatment with methanol extract of Cranberry fruit (200 mg/Kg.B.W) comparing with aqueous extract of Cranberry fruit and 2 mg/Kg.B.W. of Gentamicin. These parameters used in this current study as indicator for curing from infection. These findings indicated that cranberry extract was effective at all levels in inhibiting E. coli O157:H7; thus it possesses antimicrobial activity and hold great promise as an antimicrobial agent.
Abstract: With the prevalence of inflammatory bowel disease (IBD) and its associated risk for development of colorectal cancer, it is of great importance to prevent and treat IBD. However, due to the complexity of etiology and potentially serious adverse effects, treatment options for IBD are relatively limited. Thus, the purpose of this study was to identify a safe food-based approach for the prevention and treatment of IBD. In this study, we tested the effects of cranberry products on preventing dextran sulphate sodium-induced murine colitis. Our results suggest that both cranberry extract and dried cranberries-fed groups had a significantly reduced disease activity index, where dried cranberries were more effective in preventing colitis than cranberry extract. Shortening of colon length, colonic myeloperoxidase activity and production of pro-inflammatory cytokines were attenuated in animals fed dried cranberries compared to the controls. The current report suggests that cranberries can be applied to prevent and reduce the symptoms of IBD.
Abstract: BACKGROUND & OBJECTIVES: Emergence of antimicrobial resistance in Pseudomonas aeruginosa has led to the search for alternative agents for infections control. Natural products have been a good alternative to present antibiotics. The present study was undertaken to evaluate the effectiveness of cranberry in attenuation of virulence of P. aeruginosa in experimental urinary tract infection (UTI) in mouse model. Efforts were also directed to explore the action of cranberry towards virulence of P. aeruginosa through quorum sensing (QS) inhibition.
METHODS: Efficacy of cranberry was evaluated in an experimental UTI mouse model and on production of QS signals, alginate, pyochelin, haemolysin, phospholipase-C, cell-surface hydrophobicity, uroepithelial cell-adhesion assay and biofilm formation by already standardized methods.
RESULTS: Presence of cranberry showed significant decline in the production of QS signals, biofilm formation and virulence factors of P. aeruginosa in vitro (P<0.001). Further, cranberry was found to be useful in prevention of experimental UTI in mouse model as indicated by reduced renal bacterial colonization and kidney tissues destruction.
INTERPRETATION & CONCLUSIONS: The findings of the present study indicated that cranberry inhibited QS and hence elaboration of virulence factors of P. aeruginosa. It also affected the adherence ability of this pathogen. This approach can lead to the discovery of new category of safe anti-bacterial drugs from dietary sources such as cranberry with reduced toxicity without the risk of antibiotic resistance.
Abstract: Consumption of polyphenol-rich foods is associated with lower risk from many chronic diseases. We hypothesized that a single dose of cranberry beverage would improve indices of oxidative stress, inflammation, and urinary antibacterial adhesion activity in healthy humans. Six males and 6 females (18-35 years; body mass index, 19-25 kg/m(2)) consumed placebo, cranberry leaf extract beverage, or low-calorie cranberry juice cocktail (LCJC) once in a randomized, double-blind, placebo-controlled cross-over experimental design trial. The washout period between beverages was 1 week. Blood was collected 0, 2, 4, 8, and 24 hours after beverage consumption for measuring oxidative and inflammatory biomarkers. Urine was collected at 0, 0 to 3, 3 to 6, 6 to 9, 9 to 12, and 24 hours postintervention to assess antibacterial adhesion activity. Consumption of cranberry leaf extract beverage elevated (P < .05) blood glutathione peroxidase activity, whereas LCJC consumption increased (P < .05) glutathione concentrations and superoxide dismutase activity compared with placebo. Cranberry leaf extract beverage and LCJC consumption had no effect on the inflammatory biomarkers measured as compared with placebo. At 0 to 3 hours postconsumption, urine from participants who consumed cranberry beverages had higher (P < .05) ex vivo antiadhesion activity against P-fimbriated Escherichia coli compared with placebo. An acute dose of cranberry beverages improved biomarkers of antioxidant status and inhibition of bacterial adhesion in urine. Copyright 2014 Elsevier Inc. All rights reserved.
Abstract: Basic studies have proven that cranberries may prevent urinary tract infections through changing the adhesiveness of Escherichia coli (E. coli) to urothelial cells. Various cranberry preparations, including extract powder, capsules, and juice, have been shown to be effective in clinical and epidemiological research. Because cranberries are most commonly consumed as juice in a diluted concentration, the aim of this study was to investigate whether the equivalent daily dose of cranberry juice is sufficient to modify host urine to change the uropathogenicity of E. coli. Urine from rats taking an equivalent daily dose of cranberry juice has been shown to decrease the capability of E. coli in hemagglutination, urothelium adhesion, nematode killing, and biofilm formation. All these changes occurred after E. coli was incubated in cranberry metabolite-containing urine, defined as urine opsonization. Urine opsonization of E. coli resulted in 40.9% (p = 0.0038) decrease in hemagglutination ability, 66.7% (p = 0.0181) decrease in urothelium adhesiveness, 16.7% (p = 0.0004) increase in the 50% lethal time in killing nematodes, and 53.9% (p = 5.9 x 10(-4)) decrease in biofilm formation. Thus, an equivalent daily dose of cranberry juice should be considered sufficiently potent to demonstrate urine opsonization in E. coli.
Abstract: BACKGROUND: Cranberry fruits possess many biological activities partly due to their various phenolic compounds; however the underlying modes of action are poorly understood. We studied the effect of cranberry fruit extracts on the gene expression of Staphylococcus aureus to identify specific cellular processes involved in the antibacterial action.
METHODS: Transcriptional profiles of four S. aureus strains grown in broth supplemented or not with 2 mg/ml of a commercial cranberry preparation (Nutricran90) were compared using DNA arrays to reveal gene modulations serving as markers for biological activity. Ethanol extracted pressed cakes from fresh fruits also produced various fractions and their effects on marker genes were demonstrated by qPCR. Minimal inhibitory concentrations (MICs) of the most effective cranberry fraction (FC111) were determined against multiple S. aureus strains and drug interactions with -lactam antibiotics were also evaluated. Incorporation assays with [(3)H]-radiolabeled precursors were performed to evaluate the effect of FC111 on DNA, RNA, peptidoglycan (PG) and protein biosynthesis.
RESULTS: Treatment of S. aureus with Nutricran90 or FC111 revealed a transcriptional signature typical of PG-acting antibiotics (up-regulation of genes vraR/S, murZ, lytM, pbp2, sgtB, fmt). The effect of FC111 on PG was confirmed by the marked inhibition of incorporation of D-[(3)H]alanine. The combination of -lactams and FC111 in checkerboard assays revealed a synergistic activity against S. aureus including strain MRSA COL, which showed a 512-fold drop of amoxicillin MIC in the presence of FC111 at MIC/8. Finally, a therapeutic proof of concept was established in a mouse mastitis model of infection. S. aureus-infected mammary glands were treated with amoxicillin, FC111 or a combination of both; only the combination significantly reduced bacterial counts from infected glands (P<0.05) compared to the untreated mice.
CONCLUSIONS: The cranberry fraction FC111 affects PG synthesis of S. aureus and acts in synergy with -lactam antibiotics. Such a fraction easily obtained from poorly exploited press-cake residues, may find interesting applications in the agri-food sector and help reduce antibiotic usage in animal food production.
Abstract: BACKGROUND: Periodontitis is a polymicrobial infectious disease. A novel potential chemical treatment modality may lie in bacterial anti-adhesive materials, such as cranberry juice fractions. The aim of this study is to explore the effect of high molecular weight cranberry constituent (non-dialyzable material [NDM]) on the virulence of a mixed infection with Porphyromonas gingivalis and Fusobacterium nucleatum in mice.
METHODS: In vitro, the anti-adhesive property of NDM was validated on epithelial cell culture, and inhibition of coaggregation was tested using a coaggregation assay. The in vivo effect was tested on the outcome of experimental periodontitis induced by a P. gingivalis and F. nucleatum mixed infection, and also on the local host response using the subcutaneous chamber model of infection. Phagocytosis was also tested on RAW macrophages by the use of fluorescent-labeled bacteria.
RESULTS: NDM was found to inhibit the adhesion of both species of bacteria onto epithelial cells and to inhibit coaggregation in a dose-dependent manner. NDM consumption by mice attenuated the severity of experimental periodontitis compared with a mixed infection without NDM treatment. In infected subcutaneous chambers, NDM alone reduced tumor necrosis factor-alpha (TNF-alpha) levels induced by the mixed infection. In vitro, NDM eliminated TNF-alpha expression by macrophages that were exposed to P. gingivalis and F. nucleatum, without impairing their viability. Furthermore, NDM increased the phagocytosis of P. gingivalis.
CONCLUSIONS: The results indicate that the use of NDM may hold potential protective and/or preventive modalities in periodontal disease. Underlying mechanisms for this trait may perhaps be the anti-adhesive properties of NDM or its potential effect on inflammation.
Abstract: The experiment consisted in assessing the effectiveness of a commercial product based on cranberry extracts (pHDReg.-Biomin LTDA) in the treatment of urinary tract infections (UTI) in sows. Were used 42 sows, with gestational ages ranging between 50 and 70 days, either suffering from UTI or not. Healthy animals were differentiated from affected animals by urinalysis and urine culture. The experiment was composed of sows with UTI that received the cranberry extract product in the diet for a period of 14 days; sows negative for UTI (negative controls) and sows positive for UTI (positive controls). The former two groups did not receive the cranberry extract product in the diet. Urine samples were collected on days zero, seven and 14 after initiation of treatment. Complete urinalysis of these samples, urine specific gravity, pH, bacterial count and bacterial isolation were performed. E. coli was the most frequent isolated agent (90.62%). The results showed that the commercial product made with cranberry extract was effective in promoting a reduction of urinary pH, but did not interfere in any other parameters observed.
Abstract: Traditional first-line treatment of chronic bacterial prostatitis (CBP) is administration of empirical antibiotics. However, the efficacy rate is low and long-term antibiotic therapy can result in adverse events and bacterial resistance. For these reasons, a new treatment or preventive modality that can replace traditional antibiotic therapy is required. There are several reports that E. coli extract has a preventive effect on recurrent urinary tract infection (UTI). Cranberries are also known to have beneficial effects in preventing UTI. To evaluate the preventive effect of E. coli extract and cranberries on CBP, 48 rats were randomly divided into 4 groups; control, ciprofloxacin, E. coli extract, and cranberry groups. All drug treatments were conducted for 3 weeks, and then we developed a CBP rat model. After 4 weeks, the results of microbiological culture of prostate and urine samples as well as histological findings for the prostate were analyzed for each group. The infection rate in the ciprofloxacin group was significantly lower than that in the control group. The microbiological cultures of the prostate and urine samples demonstrated reduced bacterial growth in all experimental groups compared with the control group. Histopathologic examination showed significantly decreased prostatic inflammation in all groups compared with the control group. These results suggest that E. coli extract has a potential preventive effect on the development of CBP, and cranberry also exhibits promising activity in this context
Abstract: The glycosides of flavonoid, anthocyanins and A type proanthocyanidins in cranberry concentrate were characterized and quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Cranberry concentrate (1 g/body weight) was orally gavaged to Fischer-344 rats (n = 6), and blood and urine samples were collected over 24 h periods. Quercetin, 3'-O-methylquercetin (isorhamnetin), myricetin, kaempferol, and proanthocyanidin dimer A2, together with thirteen conjugated metabolites of quercetin and methylquercetin and intact peonidin 3-O-galactoside and cyanidin 3-O-galactoside were identified in the rat urine after cranberry treatment. Very low levels of isorhamnetin (0.48 +/- 0.09 ng/mL) and proanthocyanidin dimer A2 (0.541 +/- 0.10 ng/mL) were found in plasma samples after 1 h of cranberry administration. Although no quercetin was detected in plasma, MRM analysis of the methanolic extract of urinary bladder showed that chronic administration of cranberry concentrate to rats resulted in accumulation of quercetin and isorhamnetin in the bladder. These results demonstrate that cranberry components undergo rapid metabolism and elimination into the urine of rats and are present in the urinary bladder tissue potentially allowing them to inhibit urinary bladder carcinogenesis.
Abstract: OBJECTIVES: The American cranberry proanthocyanidins (PACs) are the main responsible for its efficacy in urinary tract infections. Their mechanism of action is related to inhibition of Escherichia coli to urothelial cells. Cysticlean contains an extract of American cranberry which provides 118 mg of PACs per dose. The activity of Cysticlean tablets on Escherichia Coli adherence to bladder epithelial cells has been studied in vitro. Moreover, the activity of Cistyclean both in powder for oral suspension and tablets has been compared ex-vivo. METHODS: The rats received both Cysticlean preparations per orem, and urine from each animal was collected during the following 16 hours and preincubated with E. coli. Subsequently, bacteria were incubated with T24 cells. After 1 hour the number of bacteria adhered per cell was calculated. For the in vitro study, E. Coli preincubated at various concentrations of the products were incubated with T24 cells and the same process previously referred was carried out. RESULTS: Urine samples from rats taking Cysticlean powder for oral suspension and tablets (118 mg PACs/animal) showed an important inhibition of E. Coli adherence (83% and 52%respectively). The inferior dose of 59 mg PACs/animal also showed marked inhibition of E. Coli adherence (29% after Cysticlean tablets intake and 40% for powder). In vitro, Cysticlean showed inhibition of bacterial adherence in all tested concentrations: 5, 25 and 75 PACs mg/ml, diminishing the number og bacteria adhered to epithelial cells by 25%, 36% and 34% respectively. CONCLUSIONS: Cysticlean shows a significant inhibition of E. Coli adherence to urothelial cells. Cysticlean powder for suspensión preparation is more effective tha tablets. Cysticlean powder for suspensión is well tolerated, and compliance has been observed. Its use is very recommendable in pediatric urinary tract infection prophylaxis. Due to the variety of products with American cranberry extracts in the market, with different proanthocyanidins declared content, it would be interesting to compare their activity using established pharmacological methods.
Abstract: OBJECTIVE: To evaluate the protective effects of cranberry fruit, which have known antioxidant effects, on infection-induced oxidative renal damage in a rabbit model of vesico-ureteric reflux (VUR). MATERIALS AND METHODS: In all, 36 New Zealand male rabbits were divided into five groups, with a sham operation in four rabbits serving as the control (group 1). To create unilateral VUR the roof of the left intravesical ureter was incised, and VUR confirmed 2 weeks after surgery. In all, 32 rabbits with VUR were divided into four groups; 2, VUR alone (with sterile urine); 3, a group infected with Escherichia coli; 4, with intravesical E. coli instillation but fed cranberries; and 5, intravesical E. coli instillation plus an intraperitoneal injection with melatonin group. At 3 weeks after surgery the rabbits were killed, the kidneys obtained and examined histopathologically to evaluate inflammation, fibrosis and tubular changes. Oxidative renal damage was evaluated by measuring malondialdehyde in the renal tissue. RESULTS: Grossly, the refluxing kidney was larger than the contralateral normal kidney, and the refluxing ureter was dilated and tortuous. Microscopy of tissues from the kidneys in group 3 showed apparent periglomerular mononuclear cell infiltration, tubular dilatation and atrophy, and interstitial fibrosis. The kidneys from groups 2, 4 and 5 showed mild mononuclear cell infiltration with no interstitial fibrosis. The level of malondialdehyde in the kidneys of group 3 was significantly higher than that in group 2, 4 and 5 (P < 0.05); the level in groups 4 and 5 did not differ significantly from that in group 2. CONCLUSIONS: This study shows that cranberries have an anti-inflammatory effect through their antioxidant function and might prevent infection-induced oxidative renal damage. Thus, clinically cranberries might be used as a beneficial adjuvant treatment to prevent damage due to pyelonephritis in children with VUR.
Abstract: The chemopreventive efficacy of cranberry juice concentrate in an experimental model of urinary bladder cancer was evaluated using female Fischer-344 rats. The animals received N-butyl-N-(4-hydroxybutyl)-nitrosamine (OH-BBN) for a period of eight weeks. Cranberry juice concentrate was administered at doses of 1.0 or 0.5 ml/rat/day beginning one week after the final OH-BBN treatment and continuing until the end of the study. The urinary bladders of all the rats were weighed and examined grossly for lesions, and all masses were submitted for pathological evaluation. A dose-dependent preventive effect of cranberry treatment was observed, with a reduced number of urinary bladder cancers (38%) in the 1.0 ml/rat/day group versus the control group. The cranberry extract neither affected body weight gain nor caused other signs of toxicity. For the metabolic studies, serum and urine were collected at 4 and 12 h after the administration of the cranberry juice concentrate and were analyzed by LC-MS/MS. Quercetin and its methylated derivative were detected in the urine samples. However, no quercetin was detected in the serum samples, indicating its poor bioavailability. These data suggest that components of cranberries may be effective in preventing urinary bladder carcinogenesis.
Abstract: AIM: To study isolation and chemical characterization of pectin derived from the common cranberry Vaccinium oxycoccos L. (oxycoccusan OP) and the testing of its preventive effect on experimental colitis.
METHODS: Mice were administrated orally with OP two days prior to a rectal injection of 5% acetic acid and examined for colonic damage 24 h later. Colonic inflammation was characterized by macroscopical injury and enhanced levels of myeloperoxidase activity measured spectrophotometrically with o-phenylene diamine as the substrate. The mucus contents of the colon were determined by the Alcian blue dye binding method. Vascular permeability was estimated using 4% Evans blue passage after i.p. injection of 0.05 mol/L acetic acid.
RESULTS: In the mice treated with OP, colonic macroscopic scores (1.1+/-0.4 vs 2.7, P<0.01) and the total square area of damage (10+/-2 vs 21+/-7, P<0.01) were significantly reduced when compared with the vehicle-treated colitis group. OP was shown to decrease the tissue myeloperoxidase activity in colons (42+/-11 vs 112+/-40, P<0.01) and enhance the amount of mucus of colitis mice (0.9+/-0.1 vs 0.4+/-0.1, P<0.01). The level of colonic malondialdehyde was noted to decrease in OP-pretreated mice (3.6+/-0.7 vs 5.1+/-0.8, P<0.01). OP was found to decrease the inflammatory status of mice as was determined by reduction of vascular permeability (161+/-34 vs 241+/-21, P<0.01). Adhesion of peritoneal neutrophils and macrophages was also shown to decrease after administration of OP (141+/-50 vs 235+/-37, P<0.05).
CONCLUSION: Thus, a preventive effect of pectin from the common cranberry, namely oxycoccusan OP, on acetic acid-induced colitis in mice was detected. A reduction of neutrophil infiltration and antioxidant action may be implicated in the protective effect of oxycoccusan.
Abstract: (Epi)catechins are associated with many health benefits in humans. However, their bioavailability, excretory pattern, and extent of conjugation in animals fed different sources or levels in the diet are not well documented. Two experiments were conducted to investigate the urinary excretion of (epi)catechins after feeding of different types of berries or different levels of the same berry source to rats. Experiment 1 investigated the effects of feeding a commercially available concentrated cranberry powder (CCP) at three different levels, 3.3, 6.6, and 33 g/kg of diet, whereas experiment 2 investigated the effect of feeding freeze-dried whole cranberry (CB), blueberry (BB), or black raspberry (BRB) powder at 50 g/kg of diet. Both experiments had an AIN-93-based control and a high-fructose diet (53-65% of the diet) to which was added three levels of CCP in experiment 1 and CB, BB, and BRB in experiment 2. (Epi)catechins were excreted as free and conjugated in both intact and methylated forms. Excretion of conjugated (epi)catechins was as high as 60% of the total consumed in some cases. A majority of both catechins and epicatechins excreted in the urine was in a methylated form. Excretion of epicatechins, including their methylated forms, ranged from 30 to 47% of the ingested amount, whereas that of catechins, including their methylated forms, ranged from 9 to 31%. Urinary excretion of (epi)catechins was dose dependent and increased with the amount of (epi)catechins present in the diet. On the basis of the excretory pattern of (epi)catechins in the urine, data suggested that the bioavailability of epicatechins may be higher than that of catechins and that (epi)catechins may be more available from blueberries compared to cranberries.
Abstract: Dietary flavonoids can be converted into phenolic acids by colonic microflora. Phenolic acids can then be absorbed into the circulation and may contribute to the health-promoting effects of the parent compounds. Phenolic acids can be further metabolized in other tissues via methylation and conjugation with glucuronide or sulfate. The objectives of this study were to identify and quantify the urinary excretion of 19 phenolic acids and their conjugates in rats fed three levels of a concentrated cranberry powder (3.3, 6.6, and 33 mg/kg of diet). The basic diet used was AIN93G diet containing very low amounts of any polyphenolic compounds. Of the phenolic acids studied, the amounts excreted varied by 4 orders of magnitude, with hippuric acid being excreted in the highest quantities. Amounts of 4-hydroxyphenylacetic acid (4HPAA), 3-hydroxyphenylacetic acid (3HPAA), 3-hydroxyphenylpropionic acid (3HPPA), and 4-hydroxycinnamic acid (4HCA) excreted were in the range of 18-33 microg/mg creatinine in animals fed the highest level of cranberry powder, whereas phenylacetic acid (PAA), gallic acid (GA), 3,4-dihydroxyphenylacetic acid (34HPAA), 3,4-dihydroxybenzoic acid (34HBA), 3,4-dihydroxycinnamic acid (34HCA), and 4-hydroxy-3-methoxycinnamic acid (FA) were excreted in the urine in concentrations of 0.1-2 microg/mg creatinine. As the amount of cranberry in the diet was increased, the amount of 4HPAA excreted decreased but the percentage of conjugated 4HPAA excreted increased (from 57 to 91%). For other phenolic acids analyzed, the percentage excreted in the conjugated form was approximately constant across levels of cranberry in the diet and ranged from 65 to 100% for the individual phenolic acids. Studies of bioactivity and health effects need to consider more than just the compound(s) in the food, because they can be metabolized to other lower molecular weight compounds, which in turn may also be methylated or conjugated in some form that may affect the perceived health effects.
Abstract: Cranberry crude extracts, in various vehicles, have shown inhibitory effects on the formation of oral biofilms in vitro. The presence of proanthocyanidins (PAC) in cranberry extracts has been linked to biological activities against specific virulence attributes of Streptococcus mutans, e.g. the inhibition of glucosyltransferase (Gtf) activity. The aim of the present study was to determine the influence of a highly purified and chemically defined cranberry PAC fraction on S. mutans biofilm formation on saliva-coated hydroxyapatite surface, and on dental caries development in Sprague-Dawley rats. In addition, we examined the ability of specific PAC (ranging from low-molecular-weight monomers and dimers to high-molecular-weight oligomers/polymers) to inhibit GtfB activity and glycolytic pH drop by S. mutans cells, in an attempt to identify specific bioactive compounds. Topical applications (60-second exposure, twice daily) with PAC (1.5 mg/ml) during biofilm formation resulted in less biomass and fewer insoluble polysaccharides than the biofilms treated with vehicle control had (10% ethanol, v/v; p < 0.05). The incidence of smooth-surface caries in rats was significantly reduced by PAC treatment (twice daily), and resulted in less severe carious lesions compared to the vehicle control group (p < 0.05); the animals treated with PAC also showed significantly less caries severity on sulcal surfaces (p < 0.05). Furthermore, specific A-type PAC oligomers (dimers to dodecamers; 0.1 mg/ml) effectively diminished the synthesis of insoluble glucans by GtfB adsorbed on a saliva-coated hydroxyapatite surface, and also affected bacterial glycolysis. Our data show that cranberry PAC reduced the formation of biofilms by S. mutans in vitro and dental caries development in vivo, which may be attributed to the presence of specific bioactive A-type dimers and oligomers.