Preparation, characterization, and dual protection of Ficus hirta Vahl polysaccharide-zinc complex against oxidative stress and inflammation-induced intestinal barrier damage

The edible and medicinal plant Ficus hirta Vahl, which is native to China, was used as the source material in this study. The present study focused on synthesizing a polysaccharide–zinc complex derived from Ficus hirta Vahl (FHVP-Zn) and evaluating its stability, safety, and biological activity. Comprehensive characterization (FT-IR, XPS, thermal analysis, and SEM) revealed that FHVP-Zn formation altered the physicochemical properties of the polysaccharide, indicating good stability, while subsequent cytotoxicity assays confirmed its safety. During the simulated digestion, FHVP-Zn demonstrated a greater capacity for reducing sugar release than FHVP did. To investigate the protective effects of FHVP and FHVP-Zn, this study employed a Caco-2 cell monolayer model for systematic evaluation using two injury models: oxidative stress and inflammation (TNF-α). Results indicate that both FHVP and FHVP-Zn effectively counteract damage-induced declines in cell viability and excessive ROS production, while also preventing disruption of epithelial barrier integrity. Specifically, both significantly increased trans-epithelial electrical resistance (TEER) values, reduced permeability of the fluorescent marker (FITC-D4), and reversed the injury-induced downregulation of tight junction protein (ZO-1, Claudin-1) expression. In TNF-α-induced inflammatory models, both compounds also exhibited dose-dependent inhibition of key proinflammatory cytokine (IL-6, IL-8, IL-1β) mRNA expression. In summary, FHVP-Zn effectively protects intestinal epithelial cells from oxidative and inflammatory damage through synergistic antioxidant, barrier-maintaining, and anti-inflammatory actions.