Fractionation, preliminary structural characterization and bioactivities of polysaccharides from Sargassum pallidum

Preparation, Characterization, and Bioactivities of Polysaccharide-Nano-Selenium and Selenized Polysaccharides from Acanthopanax senticosus

Acanthopanax senticosus polysaccharide-nano-selenium (ASPS-SENPS) and A. selenopanax selenized polysaccharides (Se-ASPS) were synthesized, and their characterization and biological properties were compared. The acid extraction method was used to extract the polysaccharides of A. selenopanax, followed by decolorization using the hydrogen peroxide method and deproteinization based on the Sevage method, and the purification of A. senticosus polysaccharides (ASPS) was carried out using the cellulose DEAE-52 ion column layer analysis method. An A. senticosus polysaccharide-nano-selenium complex was synthesized by a chemical reduction method using ASPS as dispersants. The selenization of polysaccharides from A. selenopanax was carried out using the HNO3-Na2SeO3 method. The chemical compositions, scanning electron microscopy images, infrared spectra, and antioxidant properties of ASPS-SENPS and Se-ASPS were studied, and they were also subjected to thermogravimetric analysis. The results indicated that the optimal conditions for the synthesis of ASPS-SENPS include the following: when ASPS accounts for 10%, the ratio of ascorbic acid and sodium selenium should be 4:1, the response time should be 4 h, and the reaction temperature should be 50 °C. The most favorable conditions for the synthesis of Se-ASPS were as follows: m (Na2SeO3):m (ASPS) = 4:5, response temperature = 50 °C, and response time = 11.0 h. In the in vitro antioxidant assay, when the mass concentration of Se-ASPS and ASPS-SENPS was 5 mg/mL, the removal rates for DPPH free radicals were 88.44 ± 2.83% and 98.89 ± 3.57%, respectively, and the removal rates for ABTS free radicals were 90.11 ± 3.43% and 98.99 ± 1.73%, respectively, stronger than those for ASPS. The current study compares the physiological and bioactivity effects of ASPS-SENPS and Se-ASPS, providing a basis for future studies on polysaccharides.

Isolation, structure characterization and in vitro immune-enhancing activity of a glucan from the peels of stem lettuce (Lactuca sativa)

BACKGROUND

Stem lettuce is a medicinal and edible plant. The peels, accounting for 300-400 g kg-1 raw stem lettuce and containing polysaccharides 200 g kg-1 , are discarded as industrial waste, causing environment pollution and resource waste.

RESULTS

A polysaccharide named PPSL10-2 was obtained from the peels of stem lettuce after hot water extraction, and gradation with cascade ultrafiltration and purification using DEAE-Sepharose cellulose. The purity and molecular weight of PPSL10-2 is 96.10% and 2.2 × 104  Da respectively, as detected by high-performance gel permeation chromatography. PPSL10-2 was found to be an α-(1→4)-d-glucan that branched at O-6 with a terminal 1-linked α-d-Glcp as side chain, and devoid of helix conformation, which was characterized by monosaccharide composition analysis, Fourier-transform infrared spectroscopy, Congo red test, scanning electron microscopy, methylation analysis and NMR spectroscopy. Furthermore, PPSL10-2 exhibited potent immune-enhancing effect by improving proliferation and phagocytosis, promoting the secretion of nitric oxide and cytokines, as well as the expression of related genes in RAW264.7 macrophages.

CONCLUSION

The findings of the present study suggest that peels as an agricultural by-product of stem lettuce are good sources of polysaccharides, which could be developed as immunopotentiator for improving human health. © 2023 Society of Chemical Industry.

Research progress in the preparation, structural characterization, and biological activities of polysaccharides from traditional Chinese medicine

Traditional Chinese medicines are tremendous sources of polysaccharides, which are of great interest in the human welfare system as natural medicines, food, and cosmetics. This review aims to highlight the recent trends in extraction (conventional and non-conventional), purification and analytic techniques of traditional Chinese medicine polysaccharides (TCMPs), and the chemical structure, biological activities (anti-tumor, hypoglycemic, antioxidant, intestinal flora regulation, immunomodulatory, anti-inflammatory, anti-aging, hypolipidemic, hepatoprotective, and other activities), and the underlying mechanisms of polysaccharides extracted from 76 diverse traditional Chinese medicines were compared and discussed. With this wide coverage, a total of 164 scientific articles were searched from the database including Google Scholar, PubMed, Web of Science, and China Knowledge Network. This comprehensive survey from previous reports indicates that TCMPs are non-toxic, highly biocompatible, and good biodegradability. Besides, this review highlights that TCMPs may be excellent functional factors and effective therapeutic drugs. Finally, the current problems and future research advances of TCMPs are also introduced. New valuable insights for the future researches regarding TCMPs are also proposed in the fields of therapeutic agents and functional foods.

Structural Characterization and In Vitro Anti-Inflammatory Activity of Polysaccharides Isolated from the Fruits of Rosa laevigata

RLPa-2 (Mw 15.6 kDa) is a polysaccharide isolated from Rosa laevigata Michx. It consists of arabinose (Ara), galactose (Gal), rhamnose (Rha), glucose (Glc), xylose (Xyl), and galacturonic acid (Gal-UA) with a molar ratio of 1.00:0.91:0.39:0.34:0.25:0.20. Structural characterization was performed by methylation and NMR analysis, which indicated that RLPa-2 might comprise →6)-α-D-Galp-(1→, →4)-α-D-GalpA-(1→, α-L-Araf-(1→, →2,4)-α-D-Glcp-(1→, β-D-Xylp, and α-L-Rhap. In addition, the bioactivity of RLPa-2 was assessed through an in vitro macrophage polarization assay. Compared to positive controls, there was a significant decrease in the expression of M1 macrophage markers (CD80, CD86) and p-STAT3/STAT3 protein. Additionally, there was a down-regulation in the production of pro-inflammatory mediators (NO, IL-6, TNF-α), indicating that M1 macrophage polarization induced with lipopolysaccharide (LPS) and interferon-γ (IFN-γ) stimulation could be inhibited by RLPa-2. These findings demonstrate that the RLPa-2 might be considered as a potential anti-inflammatory drug to reduce inflammation.

Optimization and evaluation of Atrina pectinata polysaccharides recovered by subcritical water extraction: A promising path to natural products

In this study, the recovery of Atrina pectinata posterior adductor polysaccharides (APP-PS) using subcritical water extraction (SWE) was optimized by response surface methodology (RSM) and the physicochemical and biological properties of the recovered APP-PS were evaluated. The optimal extraction conditions, which resulted in a maximum yield of 55.58 ± 1.12 %, were temperature, 152.08 °C; extraction time, 10 min; solid-liquid ratio, 30 g/600 mL. The obtained APP-PS was found to be 88.05 ± 0.17 % total sugar. Fourier transform infrared (FT-IR) and Nuclear magnetic resonance (NMR) analyses confirmed the presence of the α-coordination of D-glucan in the polymer sample. The analysis of monosaccharide composition, along with thermogravimetric analysis, revealed the typical structure of the sample, composed of glucose alone. Total phenolic contents of APP-PS were measured as 5.47 ± 0.01 mg Gallic acid/g of dry sample and total flavonoids contents were determined to be 0.78 ± 0.06 mg Quercetin/g of dry sample. For biological activities, ABTS+, DPPH and FRAP antioxidant activities were measured to be 20.00 ± 0.71, 2.35 ± 0.05 and 4.02 ± 0.07 μg Trolox equivalent/100 g of dry sample, respectively. Additionally ACE inhibitory was confirmed to be 87.02 ± 0.47 %. These results showed that SWE is an effective method to recover biofunctional materials from marine organisms.

Structural Characteristics and Multiple Bioactivities of Volvariella volvacea Polysaccharide Extracts: The Role of Extractive Solvents

The chemical structures and functional properties of plant-based polysaccharides are critically influenced by extractive solvents, but their roles are not clear. In this study, the structural characteristics and multiple bioactivities of Volvariella volvacea polysaccharides (VVPs) subjected to water (VVP-W), alkalis (sodium hydroxide, VVP-A), and acids (citric acid, VVP-C) as extractive solvents are investigated systematically. Of the above three polysaccharides, VVP-W exhibited the highest molecular weights, apparent viscosity, and viscoelastic properties. Functional analyses revealed that VVP-C had an excellent water-holding capacity, foaming properties, and emulsifying capacity, while VVP-A exhibited a promising oil-holding capacity. Moreover, VVP-C displayed strong inhibitory effects on α-amylase and α-glucosidase, which could be attributed to its content of total phenolics, proteins, and molecular weights. These findings have important implications for selecting the appropriate extraction techniques to obtain functional polysaccharides with targeted bioactive properties as food additives.

A Novel Polysaccharide from Sargassum weizhouense: Extraction Optimization, Structural Characterization, Antiviral and Antioxidant Effects

Porcine reproductive and respiratory syndrome virus (PRRSV) is one of the most economically important pathogens in the global swine industry over the past three decades. There is no licensed antiviral medication that can effectively control this infection. In the present study, the structure of SP-1 isolated and purified from Sargassum weizhouense was analyzed, and its antioxidant capacity and antiviral effect in MARC-145 cells against PRRSV were investigated. The results showed that SP-1 is a novel polysaccharide which mainly is composed of →4)-β-D-ManpA-(1→, →4)-α-L-GulpA-(1→ and a small amount of →4)-β-D-GalpA-(1→. PRRSV adsorption, replication, and release were all suppressed by SP-1. SP-1 therapy down-regulated mRNA expression of the CD163 receptor while increasing the antioxidant gene expression of Nrf2, TXNIP, and HO-1; increasing the protein expression of NQO1 and HO-1; and drastically reducing the protein expression of p-p65. The findings indicated that SP-1 reduces PRRSV adsorption, replication, and release through blocking the expression of the crucial CD163 receptor during infection. Meanwhile, SP-1 exerts antioxidant effects in PRRSV-infected cells through the activation of the Nrf2-HO1 signaling pathway.

Extraction, characterization, and biological activities of exopolysaccharides from plant root soil fungus Fusarium merismoides A6

The exploration of polysaccharides from microorganisms is of great importance. In this study, a new type of exopolysaccharide excreted by Fusarium merismoides A6 (FM-EPS) was isolated, and the extraction conditions were optimized using a response surface methodology (RSM). The extraction temperature at 0 °C, a precipitation time of 7.83 h, and an ethanol precipitation concentration of 77.64% were predicted and proved to be the best extraction conditions with the maximum extraction yield of 0.74 g/mL. Then, two fractions of F. merismoides A6 exopolysaccharides (FM-EPS1 and FM-EPS2) were obtained through DEAE Sepharose fast flow column chromatography. As indicated by monosaccharide composition analysis, both fractions mainly consisted of mannose, glucose, galactose, and ribose, with an average molecular weight of 5.14 × 104 and 6.50 × 104 g/mol, respectively. FT-IR and NMR spectroscopy indicated the FM-EPSs had both α- and β-glycosidic bonds. Moreover, the determination of antioxidant and antiproliferative activities in vitro proved that FM-EPSs had good antioxidant activities and antiproliferation activities. FM-EPS1 showed stronger antioxidant activities than FM-EPS2. FM-EPS2 showed antiproliferation activities on HeLa and HepG2 cells, while FM-EPS1 had no obvious antiproliferative activity. Therefore, FM-EPSs could be explored as potential antioxidant and anticancer agent applied in food, feed, nutraceutical, pharmaceutical, cosmetics, and chemical industries.

Characterization of Novel Exopolysaccharides from Enterococcus hirae WEHI01 and Its Immunomodulatory Activity

Exopolysaccharide (EPS) from probiotic Enterococcus hirae WEHI01 was isolated and purified by anion exchange chromatography and gel chromatography, the results of which show that the EPS consists of four fractions, namely I01-1, I01-2, I01-3, and I01-4. As the main purification components, I01-2 and I01-4 were preliminarily characterized for their structure and their immunomodulatory activity was explored. The molecular weight of I01-2 was 2.28 × 104 Da, which consists mainly of galactose, and a few other sugars including glucose, arabinose, mannose, xylose, fucose, and rhamnose, while the I01-4 was composed of galactose only and has a molecular weight of 2.59 × 104 Da. Furthermore, the results of an evaluation of immunomodulatory activity revealed that I01-2 and I01-4 could improve the viability of macrophage cells, improve phagocytosis, boost NO generation, and encourage the release of cytokines including TNF-α and IL-6 in RAW 264.7 macrophages. These results imply that I01-2 and I01-4 could improve macrophage-mediated immune responses and might be useful in the production of functional food and medications.

Characterization of Pleurotus citrinopileatus hydrolysates obtained from Actinomucor elegans proteases compared with that by commercial proteases

Pleurotus citrinopileatus, a nutritious and palatable edible mushroom, can be used as an appropriate material to prepare high-grade flavoring agents. Based on this, the current study aimed to investigate the feasibility of a productive protease system from Actinomucor elegans to prepare P. citrinopileatus hydrolysate (PCH). The Actinomucor elegans crude protease (AECP) was prepared from the solid-state fermentation product of P. citrinopileatus by A. elegans. AECP and four commercial proteases (alcalase, neutrase, papain, and protamex) were applied to acquire five kinds of PCHs. The physical-chemical properties of PCHs as well as its concentration and composition of nonvolatile compounds were comparatively analyzed. Sensory evaluation and electronic tongue analysis were utilized to evaluate sensory characteristics. AECP was found to be the most effective protease, with the highest hydrolysis degree (35.91%) and protein recovery (81.46%). The result of molecular weight distribution indicated that peptides below 500 Da were the main fraction of AECP hydrolysates, while AECP hydrolysates showed the highest content of monosodium glutamate-like (20.23 ± 0.16 mg/g) and flavor 5'-nucleotide (4.30 ± 0.07 mg/g) peptides. In summary, the AECP hydrolysate had superior sensory profiles compared with other hydrolysates. In addition, AECP hydrolysates exhibited favorable kokumi taste in which peptides below 500 Da showed the highest correlation with kokumi by the results of partial least-squares regression. These results indicated the feasibility of applying PCHs as flavor additives or seasoning in the food industry. AECP might be used as an alternative enzyme choice because of its low cost and high hydrolysis efficiency. PRACTICAL APPLICATION: Pleurotus citrinopileatus served as a potential raw material for natural seasonings because of its high protein content and appropriate ratio of umami amino acids to total amino acids. Enzymatic hydrolysis was an efficient approach to improve the flavor of P. citrinopileatus, where the choice of enzyme was one of the most critical factors. The research indicated that P. citrinopileatus hydrolysate prepared by A. elegans crude protease (AECP) exhibited an acceptable flavor, which provided theoretical support for the high-value utilization of P. citrinopileatus as food seasoning. AECP might be applied as an alternative enzyme resource because of its low cost and high hydrolysis efficiency.

A polysaccharide from Sargassum pallidum reduces obesity in high-fat diet-induced obese mice by modulating glycolipid metabolism

Sargassum pallidum polysaccharide (SPP) has been shown to have antioxidant, hypoglycemic, and hypolipidemic effects. However, the anti-obesity mechanism of SPP in obese mice remains unclear. This study aimed to investigate the anti-obesity effect and mechanism of SPP in obese mice induced by a high-fat diet (HFD). The model and experimental groups were fed with a HFD, and the experimental groups were simultaneously orally treated with degraded SPP (D-SPP) with dosages of 50, 100, and 200 mg kg-1 for 8 weeks, respectively. The results showed that oral administration of D-SPP not only dramatically suppressed body weight gain and reduced the fasting blood glucose level, but also lowered the levels of serum and hepatic lipids in HFD-induced obese mice. Histopathological analysis showed that D-SPP significantly prevented liver fat accumulation and reduced white adipose hypertrophy and adipocyte size. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis indicated that D-SPP intervention significantly down-regulated the relative expressions of adipogenesis genes. Specifically, the peroxisome proliferator-activated receptors-γ (PPAR-γ), sterol regulatory element-binding protein-1 (Srebp-1c), acetyl-CoA carboxylase-1(ACC1) and fatty acid synthase (FAS) in the liver of obese mice were decreased by 68, 53, 73, and 78%, respectively. These findings suggest that D-SPP might potentially be used as a promising dietary supplement for ameliorating obesity.

Nutraceutical potential of polyphenol-rich Sargassum species grown off the Korean coast: a review

Sargassum, a brown seaweed, has been used traditionally as food and medicine in Korea, China, and Japan. Sargassum spp. contain bioactive substances associated with health benefits, including anti-inflammatory and antioxidant effects. Thirty Sargassum spp. inhabit the Korean coast. However, their health benefits have yet to be systematically summarized. Therefore, the purpose of this article was to review the health benefits of these 30 Sargassum spp. grown off the Korean coast based on their health benefits, underlying mechanisms, and identified bioactive compounds.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01050-x.

Hemicellulosic Polysaccharides From Bamboo Leaves Promoted by Phosphotungstic Acids and Its Attenuation of Oxidative Stress in HepG2 Cells

In this work, we exploited an efficient method to release hemicellulosic polysaccharides (BLHP) from bamboo (Phyllostachys pubescens Mazel) leaves assisted by a small amount of phosphotungstic acid. Structural unit analysis proved that BLHP-A1 and BLHP-B1 samples possessed abundant low-branch chains in →4)-β-_D-Xylp-(1→ skeleton mainly consisting of Xylp, Manp, Glcp, Galp, and Araf residues. According to the results of the antioxidant activity assays in vitro, both of the two fractions demonstrated the activity for scavenging DPPH⋅ and ABTS⁺ radicals and exhibited relatively a high reducing ability compared to the recently reported polysaccharides. Moreover, the antioxidant activities of purified polysaccharides were evaluated against H₂O₂-induced oxidative stress damage in HepG2 cells. BLHP-B1 showed more activity for preventing damages from H₂O₂ in HepG2 cells by improving the enzyme activities of SOD, CAT, and GSH-Px and decreasing the production of MDA as well as suppressing reactive oxygen species (ROS) formation. This study implied that BLHP could demonstrate its attenuation ability for oxidative stress in HepG2 cells.

A polysaccharide isolated from Ganoderma lucidum ameliorates hyperglycemia through modulating gut microbiota in type 2 diabetic mice

In this study, we reported a thermal stable and non-toxic heteropolysaccharide F31, which decreased the blood glucose of diabetic mice (21.75 mmol/L) induced by high-fat diet (HFD) and streptozotocin (STZ) to 12.56 and 15.18 mmol/L (P < 0.01) at 180 and 60 mg/kg, depicting remarkable hypoglycemic effects of 42.25 and 30.21%. Moreover, F31 repaired islet cells and increased insulin secretion, promoted the synthesis and storage of glycogen in liver and improved activities of antioxidant enzymes and insulin resistances, declining HOMA-IR (43.77 mmol/mU) of diabetic mice (P < 0.01) to 17.32 and 20.96 mmol/mU at both doses. 16S rRNA gene sequencing revealed that F31 significantly decreased Firmicutes (44.92%, P < 0.01) and enhanced Bacteroidetes (33.73%, P < 0.01) and then increased B/F ratio of diabetic mice to 0.6969 (P < 0.01), even being close to normal control (P = 0.9579). F31 enriched Lactobacillus, Bacteroides and Ruminococcaceae, which may relieve glucose, insulin resistance and inflammation through decreasing the release of endotoxins into the circulation from intestine, carbohydrate fermentation in gut and activation of the intestine-brain axis. Functionally, F31 improved metabolism of gut microbiota to a normal state. These results may provide novel insights into the beneficial effect of F31 against hyperglycemia.

Chemical Characterization, Antitumor, and Immune-Enhancing Activities of Polysaccharide from Sargassum pallidum

Searching for natural products with antitumor and immune-enhancing activities is an important aspect of cancer research. Sargassum pallidum is an edible brown alga that has been used in Chinese traditional medicine for the treatment of tumors. However, the purification and application of its active components are still insufficient. In the present study, the polysaccharides from S. pallidum (SPPs) with antitumor and immune-enhancing activities were isolated and purified, and five polysaccharide fractions (SPP-0.3, SPP-0.5, SPP-0.7, SPP-1, and SPP-2) were obtained. The ratio of total saccharides, monosaccharide composition, and sulfated contents was determined, and their structures were analyzed by Fourier transform infrared spectroscopy. Moreover, bioactivity analysis showed that all five fractions had significant antitumor activity against three types of cancer cells (A549, HepG2, and B16), and can induce cancer cell apoptosis. In addition, the results indicated that SPPs can enhance the proliferation of immune cells and improve the expression levels of serum cytokines (IL-6, IL-1β, iNOS, and TNF-α). SPP-0.7 was identified as the most active fraction and selected for further purification, and its physicochemical properties and antitumor mechanism were further analyzed. Transcriptome sequencing result showed that SPP-0.7 can significantly induce the cell apoptosis, cytokine secretion, and cellular stress response process, and inhibit the normal physiological processes of cancer cells. Overall, SPPs and SPP-0.7 may be suitable for use as potential candidate agents for cancer therapy.

Structural characteristics, anti-proliferative and immunomodulatory activities of a purified polysaccharide from Lactarius volemus Fr

Lactarius volemus Fr. is an edible mushroom widely consumed in China. Polysaccharide is an important nutritional component of L. volemus. This research aimed to isolate the polysaccharide from L. volemus and study its structure and bioactivities. A purified polysaccharide was identified and named as LVF-I whose primary structure was proposed considering the comprehensive results of monosaccharide composition, periodate oxidation-smith degradation, methylation analysis, FT-IR and 1D/2D NMR spectroscopy. Then the immunomodulation of LVF-I and its inhibition effect on H1299 and MCF-7 cells were investigated. Results showed that LVF-I (12,894 Da) contained fucose, mannose, glucose and galactose. It had a backbone consisting of →4)-α-D-Glcp-(1→, →6)-β-D-Manp-(1→, →6)-α-D-Galp-(1 → and →4)-β-D-Manp-(1→. And its side chains were branched at C2 of →4)-β-D-Manp-(1 → by →6)-α-D-Galp-(1→, α-D-Glcp-(1→, α-D-Galp-(1 → and α-L-Fucp-(1→. LVF-I (250-1000 μg/mL) could inhibit the proliferation of H1299 and MCF-7 cells, while enhance the proliferative response of splenocyte and the phagocytic ability of RAW264.7. Furthermore, LVF-I (250-1000 μg/mL) significantly induced the secretion of nitric oxide, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) by up-regulating their mRNA expression in macrophages. These results suggested that LVF-I had the potential to be developed as antitumor or immunomodulatory agents by inhibiting the proliferation of tumor cells and stimulating macrophages-mediated immune responses.

Structure, Antioxidant Activity and In Vitro Hypoglycemic Activity of a Polysaccharide Purified from Tricholoma matsutake

The structure, antioxidant activity and hypoglycemic activity in vitro of a novel homogeneous polysaccharide from Tricholoma matsutake (Tmp) were investigated. Structural features suggested that Tmp was consisted of arabinose (Ara), mannose (Man), glucose (Glc) and galactose (Gal) with a molar ratio of 1.9:13.6:42.7:28.3, respectively, with a molecular weight of 72.14 kDa. The structural chain of Tmp was confirmed to contain →2,5)-α-l-Arabinofuranose (Araf)-(1→, →3,5)-α-l-Araf-(1→, β-d-Glucopyranose (Glcp)-(1→, α-d-Mannopyranose (Manp)-(1→, α-d-Galacopyranose (Galp)-(1→, →4)-β-d-Galp-(1→, →3)-β-d-Glcp-(1→, →3)-α-d-Manp-(1→, →6)-3-O-Methyl (Me)-α-d-Manp-(1→, →6)-α-d-Galp-(1→, →3,6)-β-d-Glcp-(1→, →6)-α-d-Manp-(1→ residues. Furthermore, Tmp possessed strong antioxidant activity and showed the strong inhibitory effect on α-glucosidase and α-amylase activities. Then, a further evaluation found that there was a dramatic improvement in the glucose consumption, glycogen synthesis and the activities of pyruvate kinase and hexokinase when the insulin-resistant-human hepatoma cell line (IR-HepG2) was treated with Tmp. The above results indicated that Tmp had good hypoglycemic activity and also exhibited great potentials in in terms of dealing with type 2 diabetes mellitus.

Preparation and characterization of chitosan-based edible active films incorporated with Sargassum pallidum polysaccharides by ultrasound treatment

In this study, Sargassum pallidum polysaccharides (SPPs) were incorporated into chitosan (CH) to develop a novel edible active film (CH/SPPs-US) via ultrasonication. The mechanical, water vapor permeability, surface morphology, crystallinity, antioxidant, and fruit preservation properties of CH/SPPs-US films prepared under sequences of matrix ratios and ultrasound treatment were investigated. The results revealed that the addition of SPPs combined with ultrasonic treatment could significantly enhance the transparency, elongation and tensile strength of the films whereas the water vapor permeability was decreased. Tensile strength and elongation at break of the C2/SP1.2-US film were 12.07 N and 54.18%, respectively, which were significantly higher than those for CH film. Meanwhile, the water vapor permeability value of C2/SP1.2-US was reduced by as high as 40.2% compared with that of chitosan film. In addition, antioxidant effect evaluation showed that the CH-based films added with SPPs exhibited better antioxidant activity than CH film, and ultrasonic treatment could further strengthen the antioxidant activity of the film. The CH/SPPs-US films could effectively extend the shelf life and inhibit the deterioration of the strawberry at room temperature (25 ± 1 °C) and 70% ± 5% relative humidity for 7 days. These results indicated that the CH/SPPs edible films via ultrasonication could be developed as edible packaging films for the preservation of fresh fruits.

Basil Polysaccharide Reverses Development of Experimental Model of Sepsis-Induced Secondary Staphylococcus aureus Pneumonia

Background

Basil polysaccharide (BPS) represents a main active ingredient extracted from basil (Ocimum basilicum L.), which can regulate secondary bacterial pneumonia development in the process of sepsis-mediated immunosuppression.

Methods

In this study, a dual model of sepsis-induced secondary pneumonia with cecal ligation and puncture and intratracheal instillation of Staphylococcus aureus or Pseudomonas aeruginosa was constructed.

Results

The results indicated that BPS-treated mice undergoing CLP showed resistance to secondary S. aureus pneumonia. Compared with the IgG-treated group, BPS-treated mice exhibited better survival rate along with a higher bacterial clearance rate. Additionally, BPS treatment attenuated cell apoptosis, enhanced lymphocyte and macrophage recruitment to the lung, promoted pulmonary cytokine production, and significantly enhanced CC receptor ligand 4 (CCL4). Notably, recombinant CCL4 protein could enhance the protective effect on S. aureus-induced secondary pulmonary infection of septic mice, which indicated that BPS-induced CCL4 partially mediated resistance to secondary bacterial pneumonia. In addition, BPS priming markedly promoted the phagocytosis of alveolar macrophages while killing S. aureus in vitro, which was related to the enhanced p38MAPK signal transduction pathway activation. Moreover, BPS also played a protective role in sepsis-induced secondary S. aureus pneumonia by inducing Treg cell differentiation.

Conclusions

Collectively, these results shed novel lights on the BPS treatment mechanism in sepsis-induced secondary S. aureus pneumonia in mice.

Production, purification, characterization, and biological properties of Rhodosporidium paludigenum polysaccharide

The yield of marine red yeast polysaccharide (MRYP) obtained from Rhodosporidium paludigenum was increased by optimizing fermentation conditions, and the pure polysaccharide was extracted by column chromatography. The molecular weight of pure MRYP and the ratio of mannose to glucose in components of MRYP were determined. Antioxidant and antibacterial abilities of MRYP were investigated in vitro and in vivo. The optimal fermentation parameters were as follows: Medium 4, pH = 6.72, temperature = 30.18°C, blades speed = 461.36 r/min; the optimized yield reached 4323.90 mg/L, which was 1.31 times the original yield. The sequence of factors that affected the MRYP yield was the blades speed>pH>temperature. The main components of MRYP were MYH-1 and MYH-2. The molecular weights of MYH-1 and MYH-2 were 246.92 kDa and 21.88 kDa, respectively; they accounted for 53.60% and 28.75% of total polysaccharide. In MYH-1 and MYH-2, the proportion of glucose and mannose accounted for 46.94%, 38.46%, and 67.10%, 7.17%, respectively. In vitro, the ability of scavenging DPPH•, •OH, and •O2− radical was 32.26%, 24.34%, and 22.09%; the minimum inhibitory concentration (MIC) of MRYP was 480 μg/mg. In vivo, MRYP improved the lambs’ body weight, antioxidant enzyme activity, and the number of probiotics, but it reduced the feed/gain (F/G) ratio and the number of pathogenic bacteria in 60-days-old lambs.

Black mulberry (Morus nigra L.) polysaccharide ameliorates palmitate-induced lipotoxicity in hepatocytes by activating Nrf2 signaling pathway

Black mulberry (Morus nigra L.) has shown health benefits against metabolic disorders. Lipotoxicity is considered as a potentially cause of metabolic syndrome, and there is no effective treatment. However, the protective effect and its mechanism of black mulberry against lipotoxicity are unclear. In this study, three polysaccharide fractions (BP1, BP2, BP3) were isolated from black mulberry by stepwise precipitation with 30%, 60%, and 90% of ethanol and analyzed by GPC, HPLC and FT-IR methods. BP1 exhibited a better protective effect than BP2 and BP3 on palmitic acid (PA)-induced lipotoxicity in HepG2 cells. BP1 effectively reduced PA-induced lipotoxicity by eliminating accumulation of ROS, improving mitochondrial function, reversing glutathione depletion and enhancing antioxidant enzyme activities. Mechanistically, BP1 activated the Nrf2 signaling pathway, a master regulator of the antioxidant defense system, through increasing Nrf2 nuclear translocation and phosphorylation. Collectively, these results demonstrate that BP1 has the great potential for applications in lipid disorders.

Characterization of polysaccharides from different species of brown seaweed using saccharide mapping and chromatographic analysis

Brown seaweed polysaccharides (BSPs) are one of the primary active components from brown seaweed that has a range of pharmaceutical and biomedical applications. However, the quality control of BSPs is a challenge due to their complicated structure and macromolecule. In this study, saccharide mapping based on high-performance liquid chromatography (HPLC), multi-angle laser light scattering, viscometer, and refractive index detector (HPSEC-MALLS-Vis-RID), and Fourier transform infrared (FT-IR) were used to discriminate the polysaccharides from nine different species of brown algae (BA1-9). The results showed that BSPs were composed of β-D-glucans and β-1,3-1,4-glucan linkages. The molecular weight, radius of gyration, and intrinsic viscosity of BSPs were ranging from 1.718 × 10⁵ Da to 6.630 × 10⁵ Da, 30.2 nm to 51.5 nm, and 360.99 mL/g to 865.52 mL/g, respectively. Moreover, α values of BSPs were in the range of 0.635 to 0.971, which indicated a rigid rod chain conformation. The antioxidant activities of BSPs exhibited substantial radical scavenging activities against DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS (2, 2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid) radicals, which indicated that the use of BSPs might be a potential approach for antioxidant supplements. Thus, this study gives insights about the structure-function relationship of BSPs, which will be beneficial to improve the quality of polysaccharides derived from marine algae.

Structure feature and antidepressant-like activity of a novel exopolysaccharide isolated from Marasmius androsaceus fermentation broth

The structure and antidepressant like activity of MEPS2 extracted from Marasmius androsaceus subjected to submerged fermentation was systematically studied. MEPS2 is a pyranoid polysaccharide composed of glucose and arabinose, which have a molar ratio of 0.56:0.08. The molecular weight was 85,944 Da. The NMR spectrum suggested the extracted MEPS2 contained uronic acid, and the glucosyl linkage was in α form, in accordance with the analysis of FT-IR spectrum. MEPS2 can considerably enhance the levels of noradrenalin (NE) and dopamine (DA) by ELISA. In addition, western blotting results indicated that MEPS2 can enhance the expression levels of TH, D2DR, and CAMKII. Furthermore, we found that AMPT, raclopride, and prazosin blocked the immobility and time-reducing effect of MEPS2. Overall, the antidepressant-like effect of MEPS2 may be involved in catecholamine synthesis and release, and TH, D2DR and CAMKII play an important role in this process.

Changes of digestive and fermentation properties of Sargassum pallidum polysaccharide after ultrasonic degradation and its impacts on gut microbiota

The in vitro digestive and fermentation properties of Sargassum pallidum polysaccharide (SPP) after ultrasound degradation were investigated. The results showed that SPP and its degraded fractions were not affected by human saliva, but slightly degraded by breaking glycosidic bonds under simulated gastrointestinal digestion. The DPPH radical scavenging activity, α-glucosidase inhibitory activity, and bile acid-binding capacity of SPP and its degraded fractions were decreased after digestion, which was attributed to the reduction of molecular weights (MWs) and viscosity. Furthermore, in vitro fermentation assay indicated that SPP and its degraded fractions showed good fermentability. The predominant compositional monosaccharides including arabinose, galactose, glucose, xylose, and uronic acid were significantly decreased, and the degraded SPP fractions were more easily fermented and utilized by gut bacteria. SPP and its degraded fractions could modulate gut health by decreasing the Firmicutes/Bacteroidetes ratio and increasing the relative abundances of some beneficial genera, such as Prevotella, Dialister, Phascolarctobacterium, Ruminococcus, and Bacteroides. These findings suggested that SPP and its degraded fractions exhibited similar influence on gut microbiota community, but appropriate degraded SPP fractions were more easily fermented by gut microbiota.

Isolation, Characterization and Bioactive Properties of Alkali-Extracted Polysaccharides from Enteromorpha prolifera

Four new purified polysaccharides (PAP) were isolated and purified from the Enteromorpha prolifera by alkali extraction, and further characterization was investigated. Their average molecular weights of PAP-1, PAP-2, PAP-3, and PAP-4 were estimated as 3.44 × 104, 6.42 × 104, 1.20 × 105, and 4.82 × 104 Da, respectively. The results from monosaccharide analysis indicated that PAP-1, PAP-2, PAP-3 were acidic polysaccharides and PAP-4 was a neutral polysaccharide. PAP-1 and PAP-2 mainly consist of galacturonic acid, while PAP-3 and PAP-4 mainly contained rhamnose. Congo red test showed that no triple helical structure was detected in the four polysaccharides. The antioxidant activities were investigated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), Superoxide, and 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical assay. In vitro antitumor activities were evaluated by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. PAP-1 exhibited relatively stronger antioxidant activities among the four polysaccharides in a dose-dependent manner. At a concentration of 1.00 mg/mL, the antioxidant activities of PAP-1 on the DPPH radical scavenging rate, superoxide anion radical scavenging rate, and ABTS radical rate at 1.00 mg/mL were 56.40%, 54.27%, and 42.07%, respectively. They also showed no significant inhibitory activity against MGC-803, HepG2, T24, and Bel-7402 cells. These investigations of polysaccharides provide a scientific basis for the use of E. prolifera as an ingredient in functional foods and medicines.

Isolation, purification, characterization, and immunomodulatory effects of polysaccharide from Auricularia auricula on RAW264.7 macrophages

Auricularia auricula polysaccharide (AAP) was isolated by hot-water extraction and purified to evaluate its structural and immunomodulatory effects on RAW264.7 macrophages. The results show that three kinds of Auricularia auricula polysaccharides (c-AAP) were obtained and named as AAP-I, AAP-II, and AAP-III Their further purification found that AAP-I and AAP-II were glycoproteins, and only AAP-III was a pure polysaccharide, which we named AAP for further experiments. Structural characteristics revealed that AAP was a homogeneous galactan comprising mannose, rhamnose, gluconic acid, glucose, galactose, arabinose, and fucose in a molar ratio of 5.02:0.9:0.12:4.48:0.37:1.0:0.36, and the average molecular weight is approximately 23.51 kDa. Methylation analysis revealed that AAP mainly consisted of 1,4-linked-Glcp, 1,4,6-linked-Glcp, terminal Glcp, 1,4-linked-Manp, 1,2,6-linked-Manp, and terminal Arap. Furthermore, the in vitro immunomodulatory activities of AAP were evaluated by cell proliferation, NO production, and phagocytic ability using RAW264.7 macrophage cells. The results show that AAP not only promoted the activation of macrophages but also provided a scientific basis for the further use of AAP. PRACTICAL APPLICATIONS: Three water-soluble polysaccharides were extracted from Auricularia auricula of Changbai Mountain, two of which contained binding proteins. Determination of molecular weight, structure, and immunoreactivity of pure polysaccharide components. The result clearly demonstrated the benefits of this plant as a healthy functional food.

Ultrasonic degradation effects on the physicochemical, rheological and antioxidant properties of polysaccharide from Sargassum pallidum

The aim of this study was to investigate the effects of ultrasound degradation on the physicochemical, rheological and antioxidant properties of Sargassum pallidum polysaccharides (SpPS). The results indicated that the ultrasound irradiation could significantly decrease the average molecule weight (MW), and particle size (Zavg) of native SpPS. The degradation pattern of SpPS was closely fitted to the first-order polymer degradation (random chain scission). The primary structure of SpPS before and after ultrasound degradation was not changed, and scanning electron microscopy (SEM) analysis showed that the morphology of SpPS was different from those of the degraded SpPS fractions. Rheological analysis indicated that the degraded SpPS solutions exhibited lower apparent viscosities than native SpPS solution at the same concentration, while the elasticity of the degraded fractions at a certain extent was enhanced. Furthermore, appropriately degraded SpPS fractions exhibited stronger DPPH and ABTS scavenging activity.

Structural characterization and biological activities of a novel polysaccharide containing N-acetylglucosamine from Ganoderma sinense

A novel homogeneous heteropolysaccharide (GSPB70-S) with a molecular weight of 2.87 kDa was isolated from Ganoderma sinense. Structural analysis showed that GSPB70-S was composed of glucose, glucosamine, mannose, and galactose with a molar ratio of 12.90:3.70:2.26:1.00. The repeating structure units of GSPB70-S were characterized by the combined application of chemical methods and nuclear magnetic resonance. GSPB70-S contains a backbone of →3)-β-D-Glcp-(1 → 4)-α-D-GlcpNAc-(1 → 4)-α-D-Manp-(1 → 3)-β-D-Glcp-(1→, with branches of β-D-Glcp-(1→, α-D-GlcpNAc-(1 → and →4)-α-D-Galp-(1→. Scanning electron microscope (SEM) showed that GSPB70-S presented a long strip shape with different thicknesses, and there were many lamellar substances on the surface. Biological research showed that GSPB70-S inhibited the activity of α-glucosidase in vitro, increased the viability of RAW 264.7 macrophages, and promoted the release of NO. In addition, GSPB70-S showed good abilities to scavenge free radicals.

Structural features, selenization modification, antioxidant and anti-tumor effects of polysaccharides from alfalfa roots

Hot water extraction and chromatographic purification methods were used to extract and purify two polysaccharides (RAPS-1 and RAPS-2) from the roots of alfalfa. Subsequently, RAPS-2 was modified using the HNO₃/Na₂SeO₃ method to obtain Se-RAPS-2. The structural features, antioxidant and in vitro anti-tumor activities of the three polysaccharides were evaluated. The structural analysis revealed that RAPS-1 (Mw = 10.0 kDa) was composed of rhamnose, xylose, arabinose, galacturonic acid, mannose and glucose, whereas RAPS-2 (Mw = 15.8 kDa) consisted of rhamnose, xylose, galacturonic acid, mannose, glucose and galactose. RAPS-1 contained 1 → 2, 1 → 4, 1 → 3, and 1 → 6 or 1 → glycosidic bonds; however, while RAPS-2 lacked 1 → 4 glycosidic linkages. The molecular weight of Se-RAPS-2 was 11.0 kDa less than that of RAPS-2. The results of activities demonstrated that Se-RAPS-2 displayed superior antioxidant activity and inhibitory effect in HepG2 cells than RAPS-1 and RAPS-2.

Preparation, Characterization, and Immuno-Enhancing Activity of Polysaccharides from Glycyrrhiza uralensis

Glycyrrhiza uralensis is a Chinese herbal medicine with various bioactivities. Three fractions (GUPS-I, GUPS-II and GUPS-III) of G. uralensis polysaccharides (GUPS) were obtained with molecular weights of 1.06, 29.1, and 14.9 kDa, respectively. The monosaccharide compositions of GUPS-II and GUPS-III were similar, while that of GUPS-I was distinctively different. The results of scanning electron microscopy, FT-IR, and NMR suggested that GUPS-II and GUPS-III were flaky with a smooth surface and contained α- and β-glycosidic linkages, while GUPS-I was granulated and contained only α-glycosidic linkages. Moreover, GUPS-II and GUPS-III exhibited better bioactivities on the maturation and cytokine production of dendritic cells (DCs) in vitro than that of GUPS-I. An in vivo experiment showed that only GUPS-II significantly enhanced the maturation of DCs. These results indicate that GUPS-II has the potential to be used in combination with cancer immunotherapy to enhance the therapeutic effect.

A novel polysaccharide isolated from Flammulina velutipes, characterization, macrophage immunomodulatory activities and its impact on gut microbiota in rats

The structural characteristics of a novel Flammulina velutipes polysaccharide (FVP2) were explored in this study. Besides, immunomodulatory activities of FVP2 on RAW 264.7 cell and its impact on gut microbiota in rats were investigated. FVP2 has a molecular weight of 18.3 kD, and its main components include galactose (19.96%), glucose (60.66%) and mannose (19.38%). By NMR analysis, the main-chain structure consisted of (1 → 3)-linked-β-D-Gal, (1 → 6) -linked-β-D-Gal, (1 → 6)-linked-α-D-Glc and (1 → 3,6)-linked-α-D-Man was identified. Results of the in vitro assays on RAW 264.7 murine macrophage cells showed FVP2 could significantly up-regulate the expression of NO, TNF-α and IL-6. FVP2 was intragastrically administered to rats for 2 weeks. Compared with the control group, two caecal short-chain fatty acids (SCFAs) concentration (isobutyric acid and butyric acid) and the abundance of beneficial microbiota of the FVP2-treated group were significantly increased (p < .05) respectively. The results demonstrated that FVP2 could effectively enhance the level of butyric acid and increase beneficial gut microbiota, which could improve the intestinal barrier function and maintain the intestinal mucosal integrity, suggesting that FVP2 could potentially be an immunomodulators or a functional food to promote intestinal health.

Influences of different drying methods on the structural characteristics and multiple bioactivities of polysaccharides from okra (Abelmoschus esculentus)

In this study, in order to evaluate the influences of drying methods on the chemical structures and bioactivities of polysaccharides from okra (OPPs), four drying methods, including microwave drying at 400 W, 600 W, and 800 W, freezing drying, hot air drying, and vacuum drying, were applied to dry okra fruits. Six different OPPs were extracted from okra dried by different drying methods. Results showed that physicochemical characteristics and bioactivities of OPPs varied by different drying methods. Noticeable variations in extraction yields, molecular weights, rheological properties, molar ratios of constituent monosaccharides, contents of uronic acids, degrees of esterification, and contents of total phenolics were observed in OPPs obtained by different drying methods. In addition, results showed that OPPs, especially OPP-H and OPP-V obtained by hot air drying and vacuum drying, respectively, exhibited remarkable antioxidant activities (ABTS, DPPH, and nitric oxide radical scavenging activities, and ferric reducing antioxidant powers), strong in vitro binding capacities (fat, cholesterol, and bile acids binding capacities), and obvious inhibitory activities on α-amylase and α-glucosidase. Results suggested that the hot air and vacuum drying techniques could be appropriate drying methods before extraction of OPPs with high bioactivities for applications in the functional food and medicine industries.