Protective anti-inflammatory effects of Vitis vinifera leaf extract against TNBS-induced colitis in mice

Background Vitis vinifera L. leaves have long been utilized in traditional medicine due to their rich phytochemical composition and potential therapeutic properties. However, their potential protective effects against intestinal inflammation have been insufficiently explored. The present study investigated the antioxidant profile and anti-inflammatory activity of Lebanese grapevine leaf extract (GVL) in a 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced murine colitis model. Methods Grapevine leaves collected from Mount Lebanon were extracted using hydroethanolic extraction and analyzed for total phenolic content, condensed tannins, and reducing power activity. Acute colitis was induced in BALB/c mice using intrarectal TNBS, followed by oral administration of GVL at different dosages. Clinical performance, colon lesions, histopathological alterations, and inflammatory cytokine gene expression were evaluated. Parametric data were analyzed using One Way ANOVA with Tukey’s post hoc test, while non parametric data (scores and gene expression) were analyzed using the Kruskal-Wallis test. Results The extract exhibited elevated concentrations of total phenolics (63.3 mg gallic acid equivalents/g extract) and condensed tannins (60.8 mg catechin equivalents/g extract), together with substantial reducing power activity (EC₅₀ = 121.4 µg/mL). TNBS administration induced marked intestinal inflammation characterized by increased colon weight, inflammatory cell infiltration, epithelial damage, and significant upregulation of IL-17, IL-23, IFN-γ, and TGF-β expression. Treatment with GVL significantly improved clinical signs and attenuated histopathological lesions. Notably, the 300 mg extract/kg body weight dose demonstrated the strongest immunomodulatory effect by restoring inflammatory cytokine expression toward basal levels comparable to healthy controls. Conclusions These findings demonstrate that Lebanese grapevine leaf extract possesses potent antioxidant and anti-inflammatory properties and may represent a promising natural candidate for the management of inflammatory intestinal disorders.