Coffee leaf polyphenol-rich extracts alleviated lipopolysaccharide-induced intestinal barrier dysfunction: Insights from a Caco-2/U937 co-culture model

Coffee leaf extract (CLE) has the potential to inhibit intestinal inflammation and protect against dysfunction; however, the mechanisms for these bioactivities remain to be fully elucidated. This study investigated the capacity of fractions derived from CLE, prepared by solvent precipitation and liquid-liquid extraction, to mitigate intestinal barrier dysfunction induced by lipopolysaccharide using the Caco-2/U937 co-culture model. The results showed that water-soluble proteins and polysaccharides recovered from CLE were the primary contributors to triggering inflammation. Among the 11 fractions recovered, the ethyl acetate fraction (WEAC) showed the highest nitric oxide inhibitory activity (half-maximal inhibitory concentration (IC 50 )?=?155.08?±?2.60?μg/mL). High-performance liquid chromatography analysis exhibited that WEAC contained the highest concentrations of phenolic compounds, including 3,5-dicaffeoylquinic acid, epicatechin, isoquercitrin, and phloridzin. WEAC significantly increased transepithelial electrical resistance values and inhibited the secretion of lactate dehydrogenase, tumor necrosis factor-α, and interleukin-8 in Caco-2/U937 co-culture cells (p?<?0.05). Additionally, WEAC improved the expression of zonula occludens 1 and claudin 1 in apical Caco-2?cells, while reducing the expression of cyclooxygenase 2 in basolateral U937?cells. Molecular docking analysis revealed that 3,5-diCQA, isoquercetin, mangiferin, and epicatechin involved in regulating membrane permeability and anti-inflammatory biomarkers. Our results suggested that a phenolic-enriched WEAC fraction recovered from coffee leaves was a potential resource for preparation of nutraceuticals or functional foods designed to ameliorate intestinal barrier dysfunction and inflammation.

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