Antiadhesive Activity and Metabolomics Analysis of Rat Urine after Cranberry (Vaccinium macrocarpon Aiton) Administration

Abstract

Cranberry (Vaccinium macrocarpon Aiton) is used to treat noncomplicated urinary tract infections (UTIs). A-type procyanidins (PAC-A) are considered the active constituents able to inhibit bacterial adhesion to the urinary epithelium. However, the role of PAC-A in UTIs is debated, because of their poor bioavailability, extensive metabolism, limited knowledge about urinary excretion, and contradictory clinical trials. The effects of 35-day cranberry supplementation (11 mg/kg PAC-A, 4 mg/kg PAC-B) were studied in healthy rats using a ultra performance liquid chromatography-mass spectrometry (UPLC-MS)-based metabolomics approach. Microbial PAC metabolites, such as valeric acid and valerolactone derivatives, were related to cranberry consumption. An increased urinary excretion of glucuronidated metabolites was also observed. In a further experiment, urine samples were collected at 2, 4, 8, and 24 h after cranberry intake and their antiadhesive properties were tested against uropathogenic Escherichia coli. The 8 h samples showed the highest activity. Changes in urinary composition were studied by ultra performance liquid chromatography-time-of-flight (UPLC-QTOF), observing the presence of PAC metabolites. The PAC-A2 levels were measured in all collected samples, and the highest amounts, on the order of ng/mL, were found in the samples collected after 4 h. Results indicate that the antiadhesive activity against uropathogenic bacteria observed after cranberry consumption is ascribable to PAC-A metabolites rather than to a direct PAC-A effect, as the measured PAC-A levels in urine was lower than those reported as active in the literature.

Keywords: E. coli; antiadhesive activity; cranberry extract; healthy rats; urine metabolomics.