A polysaccharide from Epiphyllum oxypetalum (DC.) Haw. and its immunomodulatory activity

A polysaccharide (EOP) from Epiphyllum oxypetalum (DC.) Haw. was isolated and identified, and its immunomodulatory activity was evaluated both in vitro and in vivo. By using multispectral analysis, EOP was determined to be composed of rhamnose, arabinose, galactose, and galacturonic acid at a molar ratio of 26.65:11.48:53.79:6.04, and its molecular weight was 5.77 × 10⁶ Da. In addition, backbone structure of EOP was determined to consist of (1 → 4)-linked β-Galp, (1 → 2)-linked β-Rhap, (1 → 3,4)-linked β-Galp, (1 → 2,4)-linked β-Rhap and (1 → 4) -linked α-GalpA, terminating with t-β-Arap and t-β-Galp. The in vitro immunomodulatory activity assay on RAW 264.7 cell showed that EOP increased the proliferation of macrophages, enhanced its phagocytic capability, and promoted the production of cytokines including nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6). Furthermore, the in vivo evaluation on zebrafish showed that EOP could reduce the residual content of fluorescent microspheres in zebrafish, which indicated that EOP had the capability to enhance the macrophage phagocytosis. All results suggested that EOP showed a complex structure and exhibited significant immunomodulatory activity both in vitro and in vivo that had the potential to be utilized valuably in food and medicine industries.