Abstract As a traditional Chinese medicinal and edible fungus, Monascus has been widely studied for its secondary metabolites such as Monascus pigments and γ-aminobutyric acid. However, the exopolysaccharides have not been extensively studied and this has limited their food and industrial applications. In this study, exopolysaccharides isolated from the liquid fermentation of Monascus purpureus (Hong Qu) were successfully separated into two fractions (EPS-1 and EPS-2) by DEAE-Cellulose column chromatography. A possible pigment-exopolysaccharides complex was identified. The molecular structure of the polysaccharides portion was systematically investigated using the combined techniques of FT-IR, monosaccharide analysis, methylation analysis and 1D & 2D NMR. Monosaccharide compositional analysis showed that EPS-1 was composed of mannose, glucose and galactose in the molar ratio of 8:1:11, while EPS-2 consisted of six different monosaccharides, namely, rhamnose, arabinose, xylose, mannose, glucose and galactose, with the molar ratio of 2.2:1.9:1:5.6:1.9:7.7, respectively. Moreover, the backbone of EPS-1 mainly consisted of 5-β-D-Galf (31.74 wt%) and 2-β-D-Manp (17.48 wt%) with other sugar residues including 2,6-β-D-Galf, T-α-D-Manp, 6-α-D-Manp and 3,5-β-D-Galf also detected at small percentages. Furthermore, the immunomodulatory activity of EPS-1 was investigated by RAW 264.7 cell lines. The cell proliferation and pinocytosis activity, cytokines releasing, NO production and related mRNA levels all have been determined. The results indicated that EPS-1 could significantly promote cytokines secretion including IL-6, TNF-α, and IL-10 and improve expression levels of the related mRNA.

中文翻译：

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红曲菌（红曲）液体发酵胞外多糖的结构表征和免疫调节活性

摘要 红曲霉作为一种中药材和食用菌，其次生代谢产物如红曲霉色素、γ-氨基丁酸等被广泛研究。然而，胞外多糖尚未得到广泛研究，这限制了它们的食品和工业应用。在本研究中，从红曲霉（红曲）液体发酵中分离的胞外多糖通过 DEAE-纤维素柱色谱成功分离为两个部分（EPS-1 和 EPS-2）。鉴定出可能的色素-胞外多糖复合物。使用FT-IR、单糖分析、甲基化分析和一维和二维核磁共振的组合技术系统地研究了多糖部分的分子结构。单糖组成分析表明EPS-1由甘露糖、葡萄糖和半乳糖的摩尔比为 8:1:11，而 EPS-2 由六种不同的单糖组成，即鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖，摩尔比为 2.2:1.9:1:5.6 :1.9:7.7，分别。此外，EPS-1 的骨架主要由 5-β-D-Galf (31.74 wt%) 和 2-β-D-Manp (17.48 wt%) 以及包括 2,6-β-D-Galf 在内的其他糖残基组成、T-α-D-Manp、6-α-D-Manp 和 3,5-β-D-Galf 也检测到小百分比。此外，通过 RAW 264.7 细胞系研究了 EPS-1 的免疫调节活性。细胞增殖和胞饮作用、细胞因子释放、NO产生和相关mRNA水平均已确定。结果表明EPS-1能显着促进IL-6、TNF-α、IL-10等细胞因子的分泌，提高相关mRNA的表达水平。