Abstract:The extraction of polysaccharides from Pleurotus citrinopileatus (PCP) was optimized, and the immunomodulatory effects of the purified polysaccharides were assessed. The optimal conditions to extract polysaccharides from P. citrinopileatus were determined using a single-factor response surface methodology and comprised an extraction temperature of 59.81 ℃, extraction time of 2.40 h, and liquid-solid ratio of 29.91 mL/g. Under these conditions, the predicted yield was 18.82%, and the actual yield was 18.60%. Three polysaccharide components (PCP-1, PCP-2, and PCP-3) were separated and purified from PCP using DEAE Sepharose Fast Flow column. The polysaccharide compositions and molecular weights were analyzed using ion chromatography and high-performance gel permeation chromatography. PCP-1 was found to be composed of galactose, with a molecular weight of 1.90×104 u; PCP-2 was composed of galactose and glucose at a molar ratio of 4.36:5.64, with a molecular weight of 2.76×104 u; PCP-3 was composed of fucose, glucosamine hydrochloride, galactose, glucose, and glucuronic acid at a molar ratio of 0.07:0.11:0.51:7.46:1.85, with a molecular weight of 4.81×104 u. The immunomodulatory activity of PCP in macrophage RAW264.7 cultures was evaluated in vitro. PCP-1, PCP-2, and PCP-3 at 25~200 g/mL were non-toxic to RAW264.7 cells and enhanced their proliferation. Moreover, the polysaccharides substantially increased NO release and enhanced the phagocytic ability of RAW264.7 cells. Additionally, following treatment with PCP-1, PCP-2, or PCP-3 at 200 μg/mL, NO production by RAW264.7 peaked at 11.40, 11.56, and 11.76 μmoL/L, respectively.
