Regulatory potential of a xylated rhamnoglycan from Ulva reticulata on inflammatory cytokines

Sulfated polysaccharides derived from green marine macroalgae are known for their wide range of therapeutic properties, including the mitigation of inflammatory disorders. A sulfated polysaccharide, URP-2, composed of (1 → 4) linked α-rhamnopyranose, β-xylopyranose, and β-glucuropyranose, was isolated from Ulva reticulata (Ulvaceae). URP-2 exhibited significant anti-inflammatory effects by increasing interferon (IFN)-α expression (four to ten-fold) in lipopolysaccharide (LPS)-induced CALU-1 cells in a dose-dependent manner (31.25 to 125 μg mL⁻¹), compared to LPS-induced cells. Additionally, the elevated IFN-γ levels observed in LPS-induced cells were substantially reduced (by five-fold) following treatment with URP-2 at 125 μg mL⁻¹. URP-2, at a concentration of 125 μg mL⁻¹, effectively reduced the elevated levels of interleukin (IL)-1β in LPS-induced cells, decreasing it from approximately 95% to 1.3%. Tumor necrosis factor (TNF)-α level was also reduced from 30% to approximately 1% in LPS induced CALU-1 cells. Structure–activity relationship analyses of URP-2 suggest that its potent anti-inflammatory properties are likely attributed to the presence of sulfate groups and (1 → 4) linkages. Therefore, URP-2 demonstrated promising potential as a natural alternative for the treatment of inflammatory-related disorders.