Vaccinium macrocarpon urine metabolites identification, quantification and evaluation of their effect on Candida albicans adhesion

Introduction- Candida albicans urinary tract infections (UTI) are increasingly common in hospital settings due to its high propensity to form biofilms on mucosal surface and plastic surface of indwelling devices. Vaccinium macrocarpon (cranberry) has been widely used for decades in the prevention of UTIs in the general population. Proanthocyanidins (PACs), in particular the A-type, are the main responsible for the in vitro activity. Nevertheless, there are controversial results on their presence in human urine after cranberry oral intake. The reason of such different results can be the use of different dosages as well as non-standardized cranberry products. The aim of the work was i) to identify and quantify cranberry components and metabolites in human urine after the oral intake of a highly-standardized cranberry extract (AnthocranTM, Indena S.p.A.), ii) to evaluate the urine ex vivo effect on C. albicans adhesion and biofilm formation and iii) to test the in vitro activity of a mixture of metabolites identified in the active fractions. Materials and Methods-Ten young healthy female volunteers took 2 capsules Anthocran™/day for 7 days. Urine samples were collected before starting supplementation and at the following time-points after the last dose: 1, 2, 4, 6, 10, 12, 24 hours. An HPLC-MS/MS method was set-up using a LTQ-XL-Orbitrap working in data dependent scan mode to perform the analyses. A targeted and an untargeted approach was used to identify known metabolites and compounds hereto unreported in the literature. Urine fractions were tested in vitro against the reference strain C. albicans SC5314 and eight clinical isolates from UTIs. Results- Urine fractions collected after 1 and 12 hours were found to significantly reduce the adhesion. The ex vivo effect of cranberry metabolites was then confirmed by evaluating the significant inhibitory effect of a reconstituted mixture of metabolites on C. albicans adhesion and biofilm formation. Conclusions- The data reported in the present work demonstrate that i) PACs are metabolized after cranberry oral intake, ii) urines collected following one week of cranberry treatment are able to significantly reduce C. albicans adhesion and biofilm formation, iii) the activity can be due to a synergistic effect of identified cranberry metabolites including PACs metabolites.