Cistus x incanus L. extract as a complex polyphenolic blend with retained anti-adhesive and anti-inflammatory properties in a model of E. coli-induced UTI following simulated digestion

Ethnopharmacological relevance: Cistus x incanus L. is a Mediterranean plant traditionally used to treat infective conditions, including urinary tract infections (UTI). However, experimental validation against uropathogenic Escherichia coli (UPEC) is limited. Aim of the study: To investigate the antibacterial and anti-inflammatory effects of a hydroalcoholic extract of aerial parts (CE) in an E. coli-induced UTI model, evaluating stability and efficacy after intestinal digestion. Materials and methods: T24 bladder epithelial cells were infected with UPEC CFT073 and treated with CE before and after simulated intestinal digestion (CEd). IL-6 release, bacterial growth, and adhesion were evaluated. Polyphenol content and stability were analyzed using colorimetric assays and LC-MS/MS. A methanol-insoluble fraction (IF) of CE was also tested. Results: CE inhibited IL-6 release with an IC50 of 16.05 μg/mL during infection and 0.43 μg/mL upon TNF-α stimulation; IL-8 was also reduced. CE markedly decreased UPEC adhesion to T24 cells (-79 % at 200 μg/mL). After digestion, CEd retained anti-inflammatory activity (IC50 for IL-6: 19.05 μg/mL during infection; 1.69 μg/mL with TNF-α). Flavonols remained relatively stable post-digestion, while catechins and procyanidins decreased. IF, rich in glycosidic flavonols and tannins, preserved its anti-inflammatory and antibacterial activity before and after digestion. Conclusions: These findings support, for the first time, the traditional use of Cistus x incanus in UTI, highlighting its ethnopharmacological relevance in the treatment of urinary infections. The mechanism of action, which includes anti-inflammatory and anti-adhesive activities of the extracts, has been investigated. The efficacy was observed at micromolar concentrations, which are supposed to be reached in vivo consuming Cistus x incanus food supplements. These findings lay groundwork for preclinical UTI models. Moreover, the outcomes in the present study warrant clinical investigations to consolidate our findings.