Anti-adhesion capacities of selected cranberry polyphenols and metabolites against P-type and Type-1 fimbriated uropathogenic E. coli using a fluorometric method

Adhesion of P-type and type-1 fimbriated uropathogenic E. coli (UPEC) to uroepithelial cells initiates urinary tract infections (UTIs). This research aimed to evaluate the capacities of selected cranberry polyphenols and their microbial metabolites to inhibit such adhesion in vitro using a modified fluorometric method. Data showed that the inhibition capacity of myricetin increased with concentration and plateaued at 70%. It had IC50 values of 13.2 μM against P-type E. coli and 5.50 μM against type-1 E. coli. Quercetin showed similar anti-adhesion capacities to myricetin. Procyanidin A2 and B2 had weaker anti-adhesion activities than myricetin and quercetin, with maximal inhibition capacities of 20%–30% against UPEC. Hippuric acid, a major metabolite of cranberry polyphenols in human urine, showed a maximal inhibition of 20% at 558 μM against type-1 E. coli adhesion, whereas no anti-adhesion activity against P-type E. coli was detected. The fractions of cranberry fruit powder enriched with proanthocyanidin polymers showed the highest anti-adhesion activities compared to the fractions enriched with anthocyanins, flavonols, or proanthocyanidin oligomers. Overall, the anti-adhesion activities of cranberry polyphenols and metabolites depend on their structures and the types of fimbriae on E. coli. •The extract and fraction with the highest levels of procyanidin polymers had the greatest anti-adhesion activities among the extracts and fractions.•Hippuric acid, a microbial metabolite from cranberry polyphenols, inhibited the adhesion of type-1 E. coli in vitro.•Polyphenols inhibited adhesion of E. coli by altering number and structure of fimbriae.•Anti-adhesion capacities depended on structures of polyphenols and types of E. coli fimbriae.