Abstract:A new polysaccharide LZ1 was isolated and purified using DEAE-Sepharose Fast Flow and Sephacryl S-200 HR from crude polysaccharide extract obtained from Ganoderma lucidum mycelium via hot-water extraction. The structure of LZ1 was identified and elucidated by gel permeation chromatography (GPC), scanning electron microscopy (SEM), ultraviolet spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, gas chromatography (GC), nuclear magnetic resonance (NMR) spectroscopy, periodate oxidation, and Smith degradation. The results showed that LZ1 was a homogeneous polysaccharide and did not contain impurities such as proteins and nucleic acids. The molecular weight (Mw) was determined to be 7498 u by GPC. LZ1 was an acidic polysaccharide and consisted of rhamnose, fucose, mannose, glucose, galactose, and arabinose at a molar ratio of 0.94:0.50:1.68:26.91:4.80:17.12. The main glycosidic linkage types were 1→4 and 1→2 or 1→6 and 1→3. Congo red test suggested that there were no triple helical structures in LZ1. The effect of LZ1 on the expression of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and nitric oxide (NO) was studied using murine macrophage RAW264.7 cells as an in vitro immunomodulatory model. The results showed that LZ1 significantly promoted the secretion of TNF-α, IL-6, and NO in a concentration-dependent manner, and exhibited excellent immunomodulatory activity. Evaluation of the antioxidant activity of LZ1 by a 2,2'-azobis(2-amidinopropane) dihydrochloride (AAPH)-induced oxidative hemolysis model in erythrocytes suggested that LZ1 could effectively inhibit the AAPH-induced oxidative hemolysis of erythrocytes.
