Structural characterization of a novel mannogalactoglucan from Fortunella margarita and its simulated digestion in vitro

Effects of simulated digestion on the structural characteristics and dendritic cell activation of longan polysaccharides

An active polysaccharide (LP) from longan was purified and characterized. LP consisted of galactose and glucose in a molar ratio of 1.5: 98.5, with a molecular weight of 4.67 × 10⁷ g/mol. The main backbone of LP was T-α-D-Glcp-[(1 → 6)-α-D-Glcp-(1 → 6)-α-D-Glcp]_n. After simulated gastrointestinal digestion, the molecular weight distribution, monosaccharide composition, and major glycosidic bonds of LP were not significantly changed. LP and digested LP (DLP) reduced phagocytosis and promoted IL-10 and IL-12 secretion of dendritic cells. In addition, the effects of LP and DLP on activating dendritic cells showed no significant difference. This study helps to illuminate the potential mode of immunomodulatory action of longan polysaccharides in vivo.

Chain conformation, mucoadhesive properties of fucoidan in the gastrointestinal tract and its effects on the gut microbiota

Fucoidans are valuable marine polysaccharides with various bioactivities and physicochemical properties. However, its digestive properties, mucoadhesive properties, and bioactivity in the gastrointestinal tract are still unclear. In this study, simulated digestion, fecal fermentation in vitro, and rheology models were utilized to investigate the chain conformation, influence on gut microbiota, and mucin adhesive properties of fucoidan from the sea cucumber Thelenota ananas (Ta-FUC). The results showed that Ta-FUC was nondigestible with a temporary decrease in molecular weight in gastric conditions, accompanied by the chain conformation becoming more flexible. Moreover, Ta-FUC exhibited strong mucin adhesive function in the simulated intestinal environment, with supramolecular disulfide, hydrogen, and hydrophobic interactions in order of intensity. During fermentation, Ta-FUC was degraded by the intestinal flora to produce various short-chain fatty acids and promoted the relative abundance of Bacteroidota and Firmicutes, reducing the proportion of Proteobacteria. Therefore, these results indicate that Ta-FUC could be a potential prebiotic and ingredient for developing targeted delivery systems in the functional food and pharmaceutical industries.

Ferroptosis Related Immunomodulatory Effect of a Novel Extracellular Polysaccharides from Marine Fungus Aureobasidium melanogenum

Marine fungi represent an important and sustainable resource, from which the search for novel biological substances for application in the pharmacy or food industry offers great potential. In our research, novel polysaccharide (AUM-1) was obtained from marine Aureobasidium melanogenum SCAU-266 were obtained and the molecular weight of AUM-1 was determined to be 8000 Da with 97.30% of glucose, 1.9% of mannose, and 0.08% galactose, owing to a potential backbone of α-D-Glcp-(1→2)-α-D-Manp-(1→4)-α-D-Glcp-(1→6)-(SO3-)-4-α-D-Glcp-(1→6)-1-β-D-Glcp-1→2)-α-D-Glcp-(1→6)-β-D-Glcp-1→6)-α-D-Glcp-1→4)-α-D-Glcp-6→1)-[α-D-Glcp-4]26→1)-α-D-Glcp and two side chains that consisted of α-D-Glcp-1 and α-D-Glcp-(1→6)-α-D-Glcp residues. The immunomodulatory effect of AUM-1 was identified. Then, the potential molecular mechanism by which AUM-1 may be connected to ferroptosis was indicated by metabonomics, and the expression of COX2, SLC7A11, GPX4, ACSL4, FTH1, and ROS were further verified. Thus, we first speculated that AUM-1 has a potential effect on the ferroptosis-related immunomodulatory property in RAW 264.7 cells by adjusting the expression of GPX4, regulated glutathione (oxidative), directly causing lipid peroxidation owing to the higher ROS level through the glutamate metabolism and TCA cycle. Thus, the ferroptosis related immunomodulatory effect of AUM-1 was obtained.

Application of X-ray diffraction and energy dispersive spectroscopy in the isolation of sulfated polysaccharide from Porphyra haitanensis and its antioxidant capacity under in vitro digestion

BACKGROUND

The separation and purification of Porphyra haitanensis polysaccharide (PHP), and the determination of changes in molecular weight (Mw) and antioxidant capacity after in vitro digestion, were undertaken.

RESULTS

Analysis of two polysaccharide fractions (PHP0.5-1-UF and PHP1.0-1-UF) by various techniques showed that they were very pure sulfated polysaccharides without pigment or protein. PHP0.5-1-UF was filamentous or 'tape-like' sheets, whereas PHP1.0-1-UF had some filaments and large numbers of rounded aggregates. The Mw of PHP, PHP0.5-1-UF and PHP1.0-1-UF was 2.06 × 10⁶ (±2.02%), 6.68 × 10⁶ (±3.17%), and 1.14 × 10⁶ (±3.44%) (g mol^-1 ), respectively. After in vitro digestion, the Mw of PHP, PHP0.5-1-UF, and PHP1.0-1-UF decreased. Their antioxidant capacities were markedly higher than before digestion, especially PHP0.5-1-UF and its digestion products, which might be related to the reductions in Mw.

CONCLUSION

These findings provide a greater understanding of the separation and purification of sulfated polysaccharides and the influence of digestion on biological activity. They also contribute to the practical application of sulfated polysaccharides in functional foods. © 2021 Society of Chemical Industry.

Effects of in vitro digestion and fecal fermentation on the stability and metabolic behavior of polysaccharides from Craterellus cornucopioides

The purpose of this paper is to better clarify the stability and metabolic behavior of CCPs from the perspective of digestion and metabolism, and provide research guidance for other polysaccharides with a similar structure.