Enzymatic Degradation of Gracilariopsis lemaneiformis Polysaccharide and the Antioxidant Activity of Its Degradation Products

Methylation-GC-MS/FID-Based Glycosidic Linkage Analysis of Unfractionated Polysaccharides in Red Seaweeds

Glycosidic linkage analysis was conducted on the unfractionated polysaccharides in alcohol-insoluble residues (AIRs) prepared from six red seaweeds (Gracilariopsis sp., Prionitis sp., Mastocarpus papillatus, Callophyllis sp., Mazzaella splendens, and Palmaria palmata) using GC-MS/FID analysis of partially methylated alditol acetates (PMAAs). The cell walls of P. palmata primarily contained mixed-linkage xylans and small amounts of sulfated galactans and cellulose. In contrast, the unfractionated polysaccharides of the other five species were rich in galactans displaying diverse 3,6-anhydro-galactose and galactose linkages with varied sulfation patterns. Different levels of cellulose were also observed. This glycosidic linkage method offers advantages for cellulose analysis over traditional monosaccharide analysis that is known for underrepresenting glucose in crystalline cellulose. Relative linkage compositions calculated from GC-MS and GC-FID measurements showed that anhydro sugar linkages generated more responses in the latter detection method. This improved linkage workflow presents a useful tool for studying polysaccharide structural variations across red seaweed species. Furthermore, for the first time, relative linkage compositions from GC-MS and GC-FID measurements, along with normalized FID and total ion current (TIC) chromatograms without peak assignments, were analyzed using principal component analysis (PCA) as a proof-of-concept demonstration of the technique's potential to differentiate various red seaweed species.

Study of active components and mechanisms mediating the hypolipidemic effect of Inonotus obliquus polysaccharides

Hyperlipidemia is a multifaceted metabolic disease, which is the major risk factor for atherosclerosis and cardiovascular diseases. Traditional Chinese medicine provides valuable therapeutic strategies in the treatment of hyperlipidemia. Inonotus obliquus has been used in traditional medicine to treat numerous diseases for a long time. To screen and isolate the fractions of I. obliquus polysaccharides (IOP) that can reduce blood lipid in the hyperlipemia animals and cell models, and investigate its mechanisms. The active component IOP-A2 was isolated, purified, and identified. In vivo, rats were randomly divided into blank control group (NG), the high-fat treatment group (MG), lovastatin group (PG), and IOP-A group. Compared with MG, the hyperlipidemic rats treated with IOP-A2 had decreased body weight and organ indexes, with the level of serum total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C) significantly decreased (p < .05), and level of serum high-density lipoprotein cholesterol (HDL-C) significantly increased (p < .05). Hepatocyte steatosis in hepatic lobules was significantly reduced. In vitro, the accumulation of lipid droplets in the model of fatty degeneration of HepG2 cells was significantly alleviated, and cellular TC and TG content was significantly decreased (p < .01). Moreover, the expression of recombinant cytochrome P450 7A1 (CYP7A1) and Liver X Receptor α (LXRα) were up-regulated (p < .05) both in vivo and in vitro. The results showed that IOP-A2 may exert its hypolipidemic activity by promoting cholesterol metabolism and regulating the expression of the cholesterol metabolism-related proteins CYP7A1, LXRα, SR-B1, and ABCA1.

Degradation of Angelica sinensis polysaccharide: Structures and protective activities against ethanol-induced acute liver injury

Angelica sinensis polysaccharide (ASP) possesses diverse bioactivities; however, its metabolic fate following oral administration remains poorly understood. To intuitively determine its intestinal digestion behavior after oral administration, ASP was labeled with fluorescein, and it was found to accumulate and be degraded in the cecum and colon. Therefore, we investigated the in vitro enzymatic degradation behavior and identified the products. The results showed that ASP could be degraded into fragments with molecular weights similar to those of the fragments observed in vivo. Structural characterization revealed that ASP is a highly branched acid heteropolysaccharide with AG type II domains, and its backbone is predominantly composed of 1,3-Galp, →3,6)-Galp-(1→6)-Galp-(1→, 1,4-Manp, 1,4-Rhap, 1,3-Glcp, 1,2,3,4-Galp, 1,3,4,6-Galp, 1,3,4-GalAp and 1,4-GlcAp, with branches of Araf, Glcp and Galp. In addition, the high molecular weight enzymatic degradation products (ASP H) maintained a backbone structure almost identical to that of ASP, but exhibited only partial branch changes. Then, the results of ethanol-induced acute liver injury experiments revealed that ASP and ASP H reduced the expression of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), and malondialdehyde (MDA) and increased the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) levels, thereby relieving ethanol-induced acute liver injury.

Engineered Multifunctional Zinc-Organic Framework-Based Aggregation-Induced Emission Nanozyme for Accelerating Spinal Cord Injury Recovery

Functional recovery following a spinal cord injury (SCI) is challenging. Traditional drug therapies focus on the suppression of immune responses; however, strategies for alleviating oxidative stress are lacking. Herein, we developed the zinc-organic framework (Zn@MOF)-based aggregation-induced emission-active nanozymes for accelerating recovery following SCI. A multifunctional Zn@MOF was modified with the aggregation-induced emission-active molecule 2-(4-azidobutyl)-6-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)-1H-phenalene-1,3-dione via a bioorthogonal reaction, and the resulting nanozymes were denoted as Zn@MOF-TPD. These nanozymes gradually released gallic acid and zinc ions (Zn2+) at the SCI site. The released gallic acid, a scavenger of reactive oxygen species (ROS), promoted antioxidation and alleviated inflammation, re-establishing the balance between ROS production and the antioxidant defense system. The released Zn2+ ions inhibited the activity of matrix metalloproteinase 9 (MMP-9) to facilitate the regeneration of neurons via the ROS-mediated NF-κB pathway following secondary SCI. In addition, Zn@MOF-TPD protected neurons and myelin sheaths against trauma, inhibited glial scar formation, and promoted the proliferation and differentiation of neural stem cells, thereby facilitating the repair of neurons and injured spinal cord tissue and promoting functional recovery in rats with contusive SCI. Altogether, this study suggests that Zn@MOF-TPD nanozymes possess a potential for alleviating oxidative stress-mediated pathophysiological damage and promoting motor recovery following SCI.

Ultrasound-assisted hydrogen peroxide-ascorbic acid method to degrade sweet corncob polysaccharides can help treat type 2 diabetes via multiple pathways in vivo

In this study, we aimed to investigate the impact of various ultrasound durations on the structure and bioactivity of sweet corncob polysaccharides treated with ultrasound-assisted degradation using hydrogen peroxide and ascorbic acid (H2O2-Vc). We subjected sweet corncob polysaccharides to ultrasound treatment for 0, 30, 60, and 90 min alongside the H2O2-Vc method. We then analyzed their chemical composition and structure. Additionally, we administered these polysaccharides to mice with type 2 diabetes (T2DM) through gavage at a dosage of 200 mg/kg/day. The results indicated a significant reduction in the molecular weight of the degraded sweet corncob polysaccharides, while their composition remained relatively stable. However, the basic structure of the polysaccharides was retained. In vivo experiments demonstrated that ultrasound-assisted degradation of these polysaccharides had a positive impact on T2DM, particularly the 60-minute ultrasound treatment (UH-DSCBP-60 min), which effectively controlled blood glucose levels by regulating glycolipid metabolism in the livers of mice with T2DM. This approach also reduced inflammation and oxidative stress levels and inhibited disaccharide activity in the small intestine. We demonstrated that ultrasound can positively affect the sweet corncob polysaccharides hypoglycemic activity. The findings of our study provide a theoretical foundation for the valuable utilization of sweet corncob polysaccharides.

Preparation of low molecular weight polysaccharides from Tremella fuciformis by ultrasonic-assisted H2O2-Vc method: Structural characteristics, in vivo antioxidant activity and stress resistance

Different methods were used to degrade Tremella fuciformis polysaccharides (TFP) and prepare low molecular weight polysaccharides of Tremella fuciformis (TFLP) to improve their bioavailability. It was found that the TFLP prepared by ultrasonic-assisted H2O2-Vc method showed the highest level of antioxidant activity and stress resistance in C. elegans. The structural characteristics, in vivo antioxidant and stress resistance of TFLP-1 were evaluated after isolation and purification of TFLP, it was found that TFLP-1 was an acid polysaccharide with a molecular weight of 75770 Da, which mainly composed of mannose. Meanwhile, it could regulate the antioxidant activity and stress resistance in C. elegans by upregulating the transcription of fat-5, fat-7, acs-2, glp-1, hsf-1, hsp-1, mtl-1, nhr-49, skn-1 and sod-3 mRNA. The improvement effects were closely related to the significant regulation of galactose metabolism, alpha linolenic acid metabolism, and pantothenate and CoA biosynthesis metabolic pathways. These results provided insights into the high value application of Tremella fuciformis in the food industry and the development of antioxidant related functional foods.

The preventive effect of Glycyrrhiza polysaccharide on lipopolysaccharide-induced acute colitis in mice by modulating gut microbial communities

Acute colitis is characterised by an unpredictable onset and causes intestinal flora imbalance together with microbial migration, which leads to complex parenteral diseases. Dexamethasone, a classic drug, has side effects, so it is necessary to use natural products without side effects to prevent enteritis. Glycyrrhiza polysaccharide (GPS) is an α-d-pyranoid polysaccharide with anti-inflammatory effects; however, its anti-inflammatory mechanism in the colon remains unknown. This study investigated whether GPS reduces the lipopolysaccharide (LPS)-induced inflammatory response in acute colitis. The results revealed that GPS attenuated the upregulation of tumour necrosis factor-α, interleukin (IL)-1β, and IL-6 in the serum and colon tissues and significantly reduced the malondialdehyde content in colon tissues. In addition, the 400 mg/kg GPS group showed higher relative expressions of occludin, claudin-1, and zona occludens-1 in colon tissues and lower concentrations of diamine oxidase, D-lactate, and endotoxin in the serum than the LPS group did, indicating that GPS improved the physical and chemical barrier functions of colon tissues. GPS increased the abundance of beneficial bacteria, such as Lactobacillus, Bacteroides, and Akkermansia, whereas pathogenic bacteria, such as Oscillospira and Ruminococcus were inhibited. Our findings indicate that GPS can effectively prevent LPS-induced acute colitis and exert beneficial effects on the intestinal health.

Characterization of Chlorophyll Fluorescence and Antioxidant Defense Parameters of Two Gracilariopsis lemaneiformis Strains under Different Temperatures

In this study, two Gracilariopsis lemaneiformis strains-the wild type and a green-pigmented mutant-were cultured at three temperatures (8, 20, and 30 °C) for 7 days to explore their temperature tolerance using photosynthetic performance and antioxidant defense parameters. When the two strains of G. lemaneiformis were separately cultured at 30 °C, the fast chlorophyll fluorescence intensity of the wild type decreased, whereas the green mutant showed no significant change. The decrease in the performance index on absorption basis value under heat stress was lower in the green mutant than in the wild type. In addition, the green mutant had stronger antioxidant activity at 30 °C. Furthermore, a greater decrease in the values of maximum photochemical quantum yield and performance index on an absorption basis in the green mutant indicated that it had a greater degree of inhibition of photosynthetic performance under low temperatures. However, the green mutant produced less reactive oxygen species under low temperatures, suggesting that the antioxidant potential of the green mutant might be higher. In conclusion, the green mutant exhibited heat tolerance and could recover from low-temperature damage; therefore, it has the potential for large-scale cultivation.

Preparation and structure-activity relationship of highly active black garlic polysaccharides

The aim of this study was to establish a method to improve the biological activity of polysaccharides. Three acid-treated polysaccharides (BGPS-2, BGPS-3 and BGPS-4) were obtained by treating black garlic polysaccharides (BGPS-1) with sulfuric acid at different intensities. The structure was characterized using the sulfuric acid-carbazole assay, IC, HPSEC-MALLS and FT-IR. The biological functions were evaluated using antioxidant and melanin biosynthesis inhibition assays. Compared with BGPS-1, the molecular weight of acid-treated polysaccharides significantly decreased, and the uronic acid content significantly increased. Antioxidant capacity negatively correlated with molecular weight, whereas melanin inhibition activity positively correlated with uronic acid content. BGPS-4 had the highest antioxidant capacity and the lowest molecular weight (1.25 × 10³ Da), 79.41 % lower than that of BGPS-1. BGPS-3 was the strongest inhibitor of melanin formation and had the highest uronic acid content (50.73 %), 238.2 % higher than that of BGPS-1. Molecular weight and uronic acid content were the main structural characteristics that affected the antioxidant and melanin biosynthesis inhibition activities, respectively. BGPS-1, BGPS-2, BGPS-3, and BGPS-4 all had β-linked pyranose, multi-branched, and non-triple helical spiral structures. Therefore, the acid hydrolysis method markedly modified the structural characteristics of black garlic polysaccharides, and increased their antioxidant capacity and melanin biosynthesis inhibition activity.