Fucosylated chondroitin sulfate (FCS) and fucoidan (FUC) from sea cucumber are a class of fucose-rich sulfated polymers with a complex structure found in the body wall of sea cucumber. Previous studies have demonstrated that the backbone of FCS is composed of β-D-glucuronic acid and β-D-acetylgalactosamine, whose branched chains are composed of L-fucoses of different degrees of polymerization, and that the backbone of FUC is mainly composed of α-L-fucose. Both sulfated polysaccharides contain a small amount of other monosaccharides. Sulfate groups are mainly located at positions C-4, C-6 or C-4,6 of D-acetylgalactosamine in the main chain and at positions C-4, C-3,4 or C-2,4 of L-fucose in the branched chains of FCS, and located at C-2, C-4 or C-2,4 of L-fucose in FUC. Therefore, the structures of both sulfated polymers are highly heterogeneous. The currently available techniques for structural analysis of FCS and FUC mainly include methylation analysis, two-dimensional nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Here, we give an up-to-date review on the chemical composition, structural features and common analytical techniques of sea cucumber sulfated polysaccharides. We hope this review would provide useful information for future studies on the structural analysis and structure-activity relationship of sea cucumber sulfated polysaccharides.
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Open Access
Review
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Open Access
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The polysaccharides from Spirulina platensis were extracted, purified and thermally degraded. The chemical properties and fine composition of different polysaccharide fractions were analyzed and compared.
Five polysaccharide fractions (P0, P0.2, P0.4, P0.6 and P0.8) and their degradation products were obtained by sequential protease hydrolysis, alcohol precipitation, anion exchange chromatography and thermal degradation. High performance size exclusion chromatography (HPSEC), ion chromatography (IC), high performance liquid chromatography (HPLC) and hydrophilic interaction liquid chromatography-Fourier transform mass spectrometry (HILIC-FTMS) were used to analyze the chemical properties and fine composition of different polysaccharide fractions.
The content of sulfated groups in P0, P0.2, P0.4 and P0.6 ranged from 6% to 7%, lower than that in P0.8 (14.46%). The monosaccharide composition analysis showed that P0 was a glucan. P0.2 was a heteropolysaccharide mainly composed of glucose, galactose, rhamnose, fucose and other neutral sugars, while P0.4, P0.6 and P0.8 were mainly composed of rhamnose, glucuronic acid, glucose, xylose and galactose. Through HILIC-FTMS analysis, it was found that the oligosaccharides derived from the thermal degradation of P0.2 were mainly composed of hexose monosaccharide, pentose oligosaccharides, deoxyhexose-pentose oligosaccharides and deoxyhexose-uronic acid oligosaccharides with sulfate groups being in the deoxyhexose, pentose and hexose moieties, and that the composition of the oligosaccharide chain was complicated. However, the composition of P0.4 and P0.6 was very similar, mainly composed of rhamnose-pentose oligosaccharides, rhamnose-glucuronic acid oligosaccharides, pentose disaccharides and trisaccharides with sulfate groups being in the rhamnose and pentose moieties.
There are many complex sulfated polysaccharides with different structures in S. platensis, including sulfated glucouronic acid-rhamnan as a unique sulfate polysaccharide.
Open Access
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This study aimed to compare the compositions of peptides from Engraulis japonicus and Glycine max and their immunomodulatory effects on the intestinal mucosa in mice.
The sequences of peptides from E. japonicus and G. max were analyzed by ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-MS/MS) combined with Peaks Online 1.7 software, and the differences in peptide composition were compared. The effects of the two peptides on the mucosal structure, immune factors, immunoglobulin (Ig) levels, and gene expression of factors associated with the Toll-like receptors (TLRs)/nuclear factor kappa B (NF-κB) signaling pathway in the small intestine of mice with cyclophosphamide-induced immunosuppression were investigated.
The peptide compositions from E. japonicus and G. max were quite different. Only 11% of the peptide sequences were identical between them. Administration of the peptides from E. japonicus and G. max at 300 mg/kg mb for 30 d could significantly increase the spleen index and thymus index, alleviate intestinal mucosal damage, increase the length of intestinal villi and decrease the depth of crypts in cyclophosphamide-induced immunosuppressed mice. Moreover, the inhibitory effect of cyclophosphamide on the expression of tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), interleukin-4 (IL-4), and IL-13 was ameliorated, and the secretion of IgA and secretory IgA and the gene expression of TLR-4, TLR-6, TLR-9 and NF-κB were upregulated in the small intestine mucosa.
The peptides from E. japonicus and G. max can promote the secretion of immune factors and immunoglobulins in the small intestinal mucosa and alleviate cyclophosphamide-induced intestinal mucosal damage and immunosuppression in mice by protecting the TLRs/NF-κB signaling pathway. Although the average molecular masses, amino acid compositions and polypeptide compositions of the two peptides are different and the protective effect of the peptides from E. japonicu on secretory IgA in the intestinal mucosa is more pronounced than that of the peptides from G. max, there is no significant difference between their efficacy in protecting intestinal mucosal structure and regulating mucosal immunity in mice.
Open Access
Review
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Chlorella contains a variety of polysaccharides with complex composition and structure, which are composed of various monosaccharides such as galactose, rhamnose, glucose, arabinose, mannose, xylose and glucuronic acid. The glycosidic linkages of polysaccharides are diverse, including α-1,6-glucose, β-1,3-galactose, α-1,6-galactose, α-1,3-rhamnose, α-1,2-rhamnose, α-1,5-arabinose, α-1,6-mannose and β-1,4-xylose. Some polysaccharides are modified by methylation, sulfation and acetylation. Meanwhile, many studies have shown that polysaccharides have multiple functions such as immunoregulatory, anti-inflammatory, antioxidant, anti-tumor, antibacterial and intestinal flora-regulatory effects. At present, monosaccharide composition analysis, methylation combined with gas chromatography-mass spectrometry (GC-MS) and two-dimensional nuclear magnetic resonance (2D-NMR) spectroscopy are mainly used for research on the structure of chlorella polysaccharides such as analysis of monosaccharide composition, glycosidic bond types, branch chain substitution positions and branch chain types. This review hopes to provide valuable information for the fine structural analysis and structure-activity relationship study of polysaccharides from Chlorella.
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