International Journal of Molecular Medical Science, 2024, Vol.14, No.6, 324-341 http://medscipublisher.com/index.php/ijmms 326 Figure 2 The overall highlights discussed in this review (Adopted from Wang et al., 2022a) Purification and isolation of Sanghuangporus polysaccharides often involve gradient ethanol precipitation and chromatographic techniques. For example, five homogeneous monosaccharides were obtained by gradient ethanol precipitation followed by diethylaminoethyl-cellulose (DEAE) and Sephadex G-100 separation and purification (Liu et al., 2023b). High-speed counter-current chromatography (CCC) using an aqueous diphase solvent system has also been successfully employed for one-step separation of polysaccharides, minimizing chemical variation (Yin et al., 2012). The chemical structure of Sanghuangporus polysaccharides can be preliminarily identified using various analytical techniques. High-performance liquid chromatography (HPLC), ultraviolet (UV) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), Zeta potential analysis, and scanning electron microscopy (SEM) are commonly used to characterize the polysaccharides (Liu et al., 2023b). These techniques help in determining the monosaccharide composition, glycosidic linkages, and molecular weight distribution. 2.2 Chemical composition analysis of Sanghuangporus polysaccharides Sanghuangporus polysaccharides are composed of various monosaccharides, including glucose, galactose, mannose, xylose, arabinose, and rhamnose. These components contribute to the biological activities of the polysaccharides, such as antioxidant and anti-inflammatory effects (Liu et al., 2018; Liu et al., 2023b). The specific composition and structure can vary depending on the extraction and purification methods used (Table 1). The molecular weight of Sanghuangporus polysaccharides can vary significantly, and their structural complexity is revealed through techniques such as viscometry, osmometry, precipitation methods, HPLC, GPC, HPGPC, HPSEC, SEC-MALLS-RI, and HPSEC-MALLS-RI. For example, polysaccharides purified from Sanghuangporus fungi have an average molecular weight of 20.377 kDa (Zhang et al., 2023). Structural analysis indicates that the molecular weight of these polysaccharides ranges from 1 to 1×10⁶ kDa, and there is a correlation between molecular weight and the antioxidant capacity of the polysaccharides. Low-molecular-weight polysaccharides exhibit significantly better antioxidant and free radical scavenging abilities than high-molecular-weight polysaccharides, possibly due to the more active intramolecular hydrogen bonding of O-H and electron-donating substituents. Structural analysis using methylation and two-dimensional nuclear magnetic resonance (2D-NMR) techniques indicates that these polysaccharides typically consist of complex glycosidic linkages, including 1,4-linked α-D-pyran glucose residues with branching points (Figure 3) (Cheng et al., 2020a).
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