Galactofucan from Laminaria japonica is not degraded by the human digestive system but inhibits pancreatic lipase and modifies the intestinal microbiota.

The effects of galactofucan from Laminaria japonica on the digestion and intestinal microbiota of human were investigated in the present study. Crude fraction of the sulfated polysaccharide from L. japonica (CF) and its molecular-weight homogeneous fraction (CGF-3) were prepared and characterized. In the simulated digestion model for the human saliva and gastrointestinal tract, no obvious changes in the molecular weight or the reducing sugar content of CGF-3 were observed, indicating CGF-3 is resistant to the human digestive system. Then CGF-3 did not affect the α-amylase activity while it dose-dependently inhibited the activity of pancreatic lipase partly depending on its sulfate groups. In the in vitro fermentation with the human fecal microbiota, CF did not change the total carbohydrate, reducing sugar and short chain fatty acids contents, which indicated CF was not utilized by the microbiota. However, the microbiota composition was modulated greatly by CF intervention. These findings shed a light on the better understanding of the impacts of dietary galactofucan on the digestion and intestinal microbiota.

Distribution analysis of polysaccharides comprised of uronic acid-hexose/hexosamine repeating units in various shellfish species.

Acidic polysaccharides are attractive functional ingredients in shellfish which are consumed as delicious and nutritious foods world widely. In the present study, acidic polysaccharides from 21 species of edible shellfish were characterized and quantified by analyzing their repeated disaccharides using the multiple reaction monitoring (MRM) mode of triple quadrupole mass spectrometer upon acid degradation and 1-phenyl-3-methyl-5-pyrazolone (PMP) derivatization. A total of 6 glycosaminoglycans (GAGs) and 8 non-GAGs with repeated disaccharide units of a hexuronic acid linked to a hexosamine or a hexose were detected. Among them, chondroitin sulfate, heparin, →4)-ß-GlcA-(1 → 2)-α-Man-(1 → and →3)- ß-GlcA-(1 → 3)-α-Gal-(1 → were identified unambiguously by comparing with the references. The quantification results revealed that the contents of these polysaccharide varied greatly among shellfish species with a maximum over 100 mg/100 g. Furthermore, the dendrogram of hierarchical clustering analysis indicated that the composition of acidic polysaccharides in some shellfish species was related with the genetic relationship. Thus, the present study provides a more comprehensive knowledge about the distribution of acidic polysaccharides in various shellfish species.

Sulfated polysaccharide from sea cucumber modulates the gut microbiota and its metabolites in normal mice.

Sulfated polysaccharide from sea cucumber (SCSP) has been demonstrated with various health effects, the mechanism of which, however, remains poorly understood. This study aimed to investigate the possible mechanism exhibited by gut microbiota in response to SCSP. BALB/c mice were fed diets supplemented with SCSP and depolymerized SCSP (d-SCSP) for 42 days. The microbiota composition, short chain fatty acids (SCFAs), lipopolysaccharide-binding protein (LBP), body weight and gut tissue index were analyzed. Results revealed that both SCSP and d-SCSP positively regulated the gut microbiota as indicated by the enriched microbiota diversity, SCFA-producing bacteria and sulfide-degrading bacteria, and decreased harmful bacteria. Moreover, SCSP and d-SCSP not only significantly improved the levels of microbial metabolites including SCFAs and LBP, but also effectively adjusted body weight and gut tissue index. The microbial metabolites were identified to strongly correlate with the growth performance using Pearson's correlation coefficient. We further showed that the modulating effect of SCSP on the gut microbiota was altered by free-radical depolymerization, while the microbial metabolites and related growth performance were not. These findings suggest that SCSP can be used as a gut microbiota manipulator for health promotion and alter the gut microbiota in a molecular weight (Mw) dependent manner.

Development and application of a HPLC-MS/MS method for quantitation of fucosylated chondroitin sulfate and fucoidan in sea cucumbers.

Fucosylated chondroitin sulfate (FCS) and fucoidan (FUC) are two main bioactive polysaccharides in sea cucumbers. A novel method for quantitation of FCS and FUC was developed by detecting chondroitin disaccharide and fucose produced through acid hydrolysis using HPLC-MS/MS. The present method showed satisfactory performance for both saccharides. It was applied to assay sea cucumbers (Stichopus japonicus) reared in pond grow-out or bottom sowing, and the results were compared with those obtained by traditional HPLC method and 1,9-dimethylmethylene blue test, which could only provide the total sea cucumber polysaccharide (SCP) contents. No difference of total SCP content was observed between sea cucumbers reared through different ways, while a higher ratio of FCS to FUC of sea cucumbers of pond grow-out was revealed by the present method. Thus, this novel method is potential to quantify the two polysaccharides and could be a powerful tool for quality evaluation of sea cucumbers.

Compositional analysis of sulfated polysaccharides from sea cucumber (Stichopus japonicus) released by autolysis reaction.

Autolysis is not only a major reason for postharvest quality deterioration of sea cucumber, but also a promising alternative for exogenous protease to produce peptides or polysaccharides. However, little has been known about the effects of autolysis on bioactive polysaccharides of sea cucumber. Concerning the quality and safety of sea cucumber products involved autolysis reaction, the present study focused on the chemical composition of sulfated polysaccharides (SPs) released by autolysis reaction. Chemical analysis indicated that after 3-day autolysis 63% of sulfated polysaccharides were liberated but with protein chains at their reducing ends. Then the composition of SP obtained by autolysis (A-SP) was compared with that of total SPs (T-SP) via a series of analysis techniques, including FTIR, 1H NMR, HPLC and mass spectroscopy. As indicated by the results, fucan to fucosylated chondroitin sulfate ratio was found high in A-SP compared to T-SP, fucan with a lower molecular weight was the major fraction in A-SP, and the di-sulfated Fuc residue observed in T-SP was absent in A-SP. To conclude, A-SP differed greatly from T-SP in the chemical composition, suggesting possible changes on their bioactivities.

Structural characterization and osteogenic bioactivity of a sulfated polysaccharide from pacific abalone (Haliotis discus hannai Ino).

Bone morphogenic protein-2 (BMP-2) is known to promote osteogenesis. To find novel adjuvants to enhance the activity of BMP-2, the present study investigated the structure BMP-2-induced osteogenic activity of a water-soluble polysaccharide from the gonad of pacific abalone (Haliotis discus hannai Ino) named AGSP. Through analysis of aldobiouronic acids released from AGSP, monosaccharide composition comparison of AGSP and its reduced product, and methylation analysis and NMR analysis of AGSP and its desulfated derivative, the main structure residue of AGSP was determined as →3)-GlcA(1→3)-Gal(1→ with sulfated branches comprised of prevelant Gal and minor Glc, and →4)-ß-GlcA(1→2)-α-Man(1→ residue was also found. AGSP possessed a sulfate content of 12.4% with a relative molecular weight of 6.6kDa. AGSP strengthened alkaline phosphatase activity induced by BMP-2 in a dose dependent manner at 10-200µg/mL with 425% enhancement being observed at 200µg/mL, indicating AGSP could be an adjuvant candidate to enhance osteogenic activity of BMP-2.