Chemical modification, antioxidant and α-amylase inhibitory activities of corn silk polysaccharides

Sulfated Laminarin Polysaccharides Reduce the Adhesion of Nano-COM Crystals to Renal Epithelial Cells by Inhibiting Oxidative and Endoplasmic Reticulum Stress

Purpose: Adhesion between calcium oxalate crystals and renal tubular epithelial cells is a vital cause of renal stone formation; however, the drugs that inhibit crystal adhesion and the mechanism of inhibition have yet to be explored. Methods: The cell injury model was constructed using nano-COM crystals, and changes in oxidative stress levels, endoplasmic reticulum (ER) stress levels, downstream p38 MAPK protein expression, apoptosis, adhesion protein osteopontin expression, and cell-crystal adhesion were examined in the presence of Laminarin polysaccharide (DLP) and sulfated DLP (SDLP) under protected and unprotected conditions. Results: Both DLP and SDLP inhibited nano-COM damage to human kidney proximal tubular epithelial cell (HK-2), increased cell viability, decreased ROS levels, reduced the opening of mitochondrial membrane permeability transition pore, markedly reduced ER Ca2+ ion concentration and adhesion molecule OPN expression, down-regulated the expression of ER stress signature proteins including CHOP, Caspase 12, and p38 MAPK, and decreased the apoptosis rate of cells. SDLP has a better protective effect on cells than DLP. Conclusions: SDLP protects HK-2 cells from nano-COM crystal-induced apoptosis by reducing oxidative and ER stress levels and their downstream factors, thereby reducing crystal-cell adhesion interactions and the risks of kidney stone formation.

The relationship between polysaccharide structure and its antioxidant activity needs to be systematically elucidated

Polysaccharides have a wide range of applications due to their excellent antioxidant activity. However, the low purity and unclear structure of polysaccharides have led some researchers to be skeptical about the antioxidant activity of polysaccharides. The current reports on the structure-activity relationship of polysaccharides are sporadic, so there is an urgent need to systematically summarize the antioxidant effects of polysaccharides with clear structures and the relationships between the structures to provide a scientific basis for the development and application of polysaccharides. This paper will systematically elucidate the structure-activity relationship of antioxidant polysaccharides, including the molecular weight, monosaccharide composition, glycosidic linkage, degree of branching, advanced conformation and chemical modification. For the first time, the antioxidant activity of polysaccharides is related to their chemical structure through histogram and radar map, and further studies using principal component analysis and cluster analysis. We critically discussed how the source, chemical structure and chemically modified groups of polysaccharides significantly contribute to their antioxidant activity and summarized the current research status and shortcomings of the structure-activity relationship of antioxidant polysaccharides. This review provides a theoretical basis and new perspective for further research on the structure-activity relationship of antioxidant polysaccharides and the development of natural antioxidants.

Acetylation of the polysaccharide from Houttuynia cordata rhizome and their α-glucosidase inhibition mechanism

In this study, the polysaccharide (RHCP) extracted from Houttuynia cordata rhizome was acetylated through the acetic anhydride method. The physicochemical properties of RHCP and its acetylated derivatives (Ac-RHCP) were determined by infrared spectra, scanning electron microscopy, and Congo red test. Meanwhile, the α-glucosidase inhibition mechanism of RHCP and Ac-RHCP was analyzed by inhibition kinetics, and circular dichroism and fluorescence spectroscopy. Ac-RHCP resulted in a more porous surface structure and 1.83-fold higher solubility compared with RHCP. At a concentration of 6 mg/mL, the α-glucosidase inhibition rate of Ac-RHCP was 75.40%, while that of RHCP was 44.68%. RHCP and Ac-RHCP inhibited α-glucosidase in a mixed-type manner, reduced the endogenous fluorescence of α-glucosidase, affected the microenvironment of amino acid residues, and changed the conformation of α-glucosidase. The study indicates that Ac-RHCP exhibits a certain level of α-glucosidase inhibition, demonstrating its potential as a functional food for glycemic control.

Activities of polysaccharide fractions from corn silk: Hemostatic, immune, and anti-lung cancer potentials

Corn silk is the stigma and style of corn and is rich in polysaccharides. Despite the extensive research on its polysaccharides, the hemostatic characteristics of effective parts and the related activities remain insufficiently explored. Corn silk polysaccharide (CSP) was extracted with hot water and purified using a diethylaminoethyl cellulose membrane. Then, it was separated with sephadex G-150 to obtain five fractions. These fractions were investigated for their potential in hemostasis, antioxidant, immune response, and anti-lung cancer activities. CSP-2, CSP-3, and CSP-4 significantly affected the coagulation indicators activated partial thromboplastin time (APTT) and thrombin time (TT) at 125-500 μg/mL. Corn silk flavonoids and saponins at 32.25 μg/mL significantly prolonged APTT, TT, and prothrombin time (PT). CSP-2, with potent antioxidant ability, approaches Vitamin C. At 25 μg/mL, CSPs nearly reached the phagocytosis of neutral red of lipopolysaccharides. The five fractions promoted the proliferation of RAW264.7 cells at 25-800 μg/mL and stimulated NO secretion at 25-100 μg/mL. CSP-2 also showed an 86 % inhibition rate effect on A549 at 200 μg/mL. These results indicate that CSP not only has hemostatic effects but also has immune and anti-lung cancer activities. Thus, it is a potential candidate compound with immune activity for managing bleeding in cancer.

Review of isolation, purification, structural characteristics and bioactivities of polysaccharides from Portulaca oleracea L

Portulaca oleracea L., also known as purslane, affiliates to the Portulacaceae family. It is an herbaceous succulent annual plant distributed worldwide. P. oleracea L. is renowned for its nutritional value and medicinal value, which has been utilized for thousands of years as Traditional Chinese Medicine (TCM). The extract derived from P. oleracea L. has shown efficacy in treating various diseases, including intestinal dysfunction and inflammation. Polysaccharides from P. oleracea L. (POP) are the primary constituents of the crude extract which have been found to have various biological activities, including antioxidant, antitumor, immune-stimulating, and intestinal protective effects. While many publications have highlighted on the structural identification and bioactivity evaluation of POP, the underlying structure-activity relationship of POP still remains unclear. In view of this, this review aims to focus on the extraction, purification, structural features and bioactivities of POP. In addition, the potential structure-activity relationship and the developmental perspective for future research of POP were also explored and discussed. The current review would provide a valuable research foundation and the up-to-date information for the future development and application of POP in the field of the functional foods and medicine.

Research progress on the hypoglycemic activity and mechanisms of natural polysaccharides

The incidence of diabetes, as a metabolic disease characterized by high blood sugar levels, is increasing every year. The predominantly western medicine treatment is associated with certain side effects, which has prompted people to turn their attention to natural active substances. Natural polysaccharide is a safe and low-toxic natural substance with various biological activities. Hypoglycemic activity is one of the important biological activities of natural polysaccharides, which has great potential for development. A systematic review of the latest research progress and possible molecular mechanisms of hypoglycemic activity of natural polysaccharides is of great significance for better understanding them. In this review, we systematically reviewed the relationship between the hypoglycemic activity of polysaccharides and their structure in terms of molecular weight, monosaccharide composition, and glycosidic bonds, and summarized underlying molecular mechanisms the hypoglycemic activity of natural polysaccharides. In addition, the potential mechanisms of natural polysaccharides improving the complications of diabetes were analyzed and discussed. This paper provides some valuable insights and important guidance for further research on the hypoglycemic mechanisms of natural polysaccharides.

Chemical characterization, antioxidant and immunomodulatory activities of acetylated polysaccharides from Cyperus esculentus

This research was designed to characterize the structure of Cyperus esculentus polysaccharide (CEP) and its acetylated one (ACEP), and then investigated the effects of acetylation on the changes in physicochemical properties, thermal stability, antioxidant and immunomodulatory activities. Results showed that CEP and ACEP were heteropolysaccharides consisting of glucose, mannose, arabinose and xylose. The main chain of CEP included α-1,4-Glcp residues with the branching points at the O-6 position of the α-1,6-Manp residues. Acetyl groups were substituted at the O-2 and O-6 positions of some glucose residues. Meanwhile, the acetylation remarkably improved the polysaccharides thermal stability, and the ACEP exhibited a greater antioxidant activity. Furthermore, CEP and ACEP were proved to protect RAW 264.7 cells against LPS-induced inflammation by improving cellular morphology and decreasing reactive oxygen species secretion. This study may highlight a new approach for developing a high value-added ingredient from C. esculentus for functional food industry.

Evaluation of In Vitro Antioxidant, Anti-Obesity, and Anti-Diabetic Activities of Opuntia ficus Cladodes Gel and Its Application as a Preservative Coating for Shrimp during Refrigerated Storage

Opuntia ficus cladodes (OFC) are considered one of the wastes that result from opuntia cultivation, and their disposal by traditional methods results in many environmental problems. Therefore, this study was conducted with two aims. The first was the production of OFC gel, and the evaluation of its in vitro antioxidant (by two methods, DPPH and ABTS), anti-obesity, and anti-diabetic activities. The second was an investigation of the effects of different concentrations of this gel (0, 50, and 100%) as an edible coating on the quality of shrimp during 8 days of refrigerated storage. The results showed that this gel was characterised by a high content of ash (10.42%), total carbohydrates (75.17%), and total phenols (19.79 mg GAE/g). OFC gel contained six types of sugars: arabinose, xylose, galactose, rhamnose, glucose, and uronic acid, and the most abundant was xylose (36.72%). It is also clear from the results that the OFC gel had high antioxidant properties, which were higher against DPPH than ABTS at the same concentration. OFC gel showed a high inhibition activity against lipase, α-glycosidase, and α-amylase enzymes, and their IC50 values were 1.43 mg/mL, 0.78 mg/mL, and 0.57 mg/mL, respectively. The results also stated that shrimp coated with OFC gel had lower pH, drip loss, TVB-N, and TBA values through the days of refrigerated storage. Moreover, the shrimp coated with 100% OFC gel were better than those coated with 50% OFC gel. In conclusion, OFC gel showed high potency as active antioxidant, for its enzyme anti-activities, and as an edible coating for shrimp.

Digestion profile, antioxidant, and antidiabetic capacity of Morchella esculenta exopolysaccharide: in vitro, in vivo and microbiota analysis

BACKGROUND

Novel functional polysaccharides from fungi are important nutraceuticals. An exopolysaccharide, Morchella esculenta exopolysaccharide (MEP 2), was extracted and purified from the fermentation liquor of M. esculenta. The aim of this study was to investigate its digestion profile, antioxidant capacity, and effect on the microbiota composition in diabetic mice.

RESULTS

The study found that MEP 2 was stable during in vitro saliva digestion but was partially degraded during gastric digestion. The digest enzymes exerted a negligible effect on the chemical structure of MEP 2. Molecular weight and atomic force microscope (AFM) images suggest that both smaller chains and larger aggregations were produced. Scanning electron microscope (SEM) images reveal that the surface morphology was much altered after intestinal digestion. After digestion, the antioxidant ability increased as revealed by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. Both MEP 2 and its digested components showed strong α-amylase and moderate α-glucosidase inhibition activity, leading us to further investigate its ability to modulate the diabetic symptoms. The MEP 2 treatment ameliorated the inflammatory cell infiltration and increased the size of pancreas inlets. Serum concentration of HbA1c was significantly reduced. Blood glucose level during the oral glucose tolerance test (OGTT) was also slightly lower. The MEP 2 increased the diversity of the gut microbiota and modulated the abundance of several important bacteria including Alcaligenaceae, Caulobacteraceae, Prevotella, Brevundimonas, Demequina, and several Lachnospiraceae species.

CONCLUSION

It was found that MEP 2 was partially degraded during in vitro digestion. Its potential antidiabetic bioactivity may be associated with its α-amylase inhibition and gut microbiome modulation ability. © 2023 Society of Chemical Industry.

Bioactive compounds of corn silk and their role in management of glycaemic response

Management of glycaemic response is perhaps the most critical part of antidiabetic therapy. Hypoglycaemia is an avoidable complication caused by conventional drugs used in the treatment of diabetes. It triggers commonly during the intensification of anti-hyperglycemic therapy used to render glycemic control in diabetic patients. The commercial oral hypoglycaemic drugs, insulin, herbal medicines and plant extracts are therefore used as a part of the treatment of diabetes. The demand for treating diabetes, through herbal and plant resources is due to their lesser adverse reactions and better phytochemical benefits. Corn silk has been shown to have anti-allergic, anti-inflammatory, and anti-hypertensive effects when extracted in various solvents. Corn silk has medicinal characteristics and has long been used as a traditional medicine in many nations, although the mechanism of action is unknown. The hypoglycaemic effects of corn silk are investigated in this review. The phytochemical components present in corn silk-like flavonoids, phenolics, terpenoids, tannins, sterols, and alkaloids are phytochemical components that have hypoglycemic activity and a mechanism for lowering blood glucose levels. There is a lack of a homogenized database on the hypoglycemic properties of corn silk thus the present review attempts to critically analyse it and provide specific recommendations of its doses.

Physicochemical characterization, rheological properties, and hypolipidemic and antioxidant activities of compound polysaccharides in Chinese herbal medicines by fractional precipitation

This study aimed to investigate the effects of different compound polysaccharides (CPs) extracted from Folium nelumbinis, Fructus crataegi, Fagopyrum tataricum, Lycium barbarum, Semen cassiae, and Poria cocos (w/w, 2:4:2:1:1.5:1) by gradient ethanol precipitation on the physicochemical properties and biological activities. Three CPs (CP50, CP70, and CP80) were obtained and comprised rhamnose, arabinose, xylose, mannose, glucose, and galactose in different proportions. The CPs contained different amounts of total sugar, uronic acid, and proteins. These also exhibited different physical properties, including particle size, molecular weight, microstructure, and apparent viscosity. Scavenging abilities of 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS), 1,1'-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl, and superoxide radicals of CP80 were more potent compared to those of the other two CPs. Furthermore, CP80 significantly increased serum levels of high-density lipoprotein cholesterol (HDL-C) and lipoprotein lipase (LPL), and hepatic lipase (HL) activity in the liver, while decreasing the serum levels of total cholesterol (TC), triglyceride (TG), and low-density lipoprotein cholesterol (LDL-C), along with LPS activity. Therefore, CP80 may serve as a natural novel lipid regulator in the field of medicinal and functional food.

Ultrasound-assisted extraction and characteristics of maize polysaccharides from different sites

Antitumor, antioxidant, hypoglycemic, and immunomodulatory properties are all exhibited by maize polysaccharides. With the increasing sophistication of maize polysaccharide extraction methods, enzymatic method is no longer limited to a single enzyme to extract polysaccharides, and is more often used in combination with ultrasound or microwave, or combination with different enzymes. Ultrasound has a good cell wall-breaking effect, making it easier to dislodge lignin and hemicellulose from the cellulose surface of the maize husk. The "water extraction and alcohol precipitation" method is the simplest but most resource- and time-consuming process. However, the "ultrasound-assisted extraction" and "microwave-assisted extraction" methods not only compensate for the shortcoming, but also increase the extraction rate. Herein, the preparation, structural analysis, and activities of maize polysaccharides were analyzed and discussed.

Acidic polysaccharide from corn silk: Structural & conformational properties and hepatoprotective activity

This study aimed to investigate the structural characterization, conformational properties, and hepatoprotective activity of corn silk acidic polysaccharide (CSP-50E). CSP-50E with molecular weights of 1.93 × 10⁵ g/mol was composed of Gal, Glc, Rha, Ara, Xyl, Man and uronic acid with a weight ratio of 12:25:1:2:2:5:21. Structural analysis with methylation indicated that CSP-50E mainly contained T-Manp, 4-substituted-_D-Galp/GalpA, and 4-substituted-_D-Glcp. CSP-50E presented random coils conformation in an aqueous solution based on the analysis of HPSEC. In vitro experiments showed that CSP-50E exhibited significant hepatoprotective effects, CSP-50E reduce IL-6, TNF-α content, and AST, ALT activity to protect ethanol-induced damage liver cells (HL-7702), while the polysaccharide functioned mainly through the caspase cascade and mediate the mitochondrial apoptosis pathway. In this study, we describe a novel acidic polysaccharide from corn silk with hepatoprotective activity that facilitates the development and utilization of corn silk resources.

Extraction, characterization, antioxidant and α-amylase inhibitory activities of (1 → 3)(1 → 6)-β-D-glucogalactan from Aspergillus niger ATCC 1004

The optimization of extraction, chemical characterization, and the evaluation of antioxidant activity and α-amylase inhibition capacities of the cell wall polysaccharides extracted from Aspergillus niger ATCC 1004 were studied in this paper. The response surface methodology through a factorial design of three levels indicated the optimal conditions for extraction: pH 13 and 180 min. Characterization results showed that the polysaccharide is glucogalactan, consisting of β-D-galactose-linked units (1 → 6) and β-D-linked glucose (1 → 3). The antioxidant activity was evaluated through three in vitro assays. It could effectively scavenge DPPH, ABTS and hydroxyl radicals with inhibition rates of 82.12%, 75.87% and 79.24, respectively, at 6.4 mg/mL, which were higher than those of the other polysaccharides. For inhibitory activity against α-amylase, a blocking effect of 53.7% was observed at a concentration of 2 mg/mL. Therefore, the cell wall polysaccharides of Aspergillus niger, (1 → 3)(1 → 6)-β-D-glucogalactan, seem to be a promising source for use as an antioxidant, in addition to holding an in vitro hypoglycemic potential.

Structural Characterization and Biological Activity of Polysaccharides from Stems of Houttuynia cordata

In this study, water-soluble natural polysaccharides were extracted from the stems of Houttuynia cordata Thunb (HCPS). The optimization of the hot water extraction process using response surface methodology (RSM), and the extraction factors, were analyzed by multiple stepwise regression analysis and Pearson analysis. Then, the structural characterization and biological activity of the HCPS were investigated. The results indicated that the maximum extraction yield (2.43%) of the HCPS was obtained at the optimal condition (extraction temperature for 90 °C, extraction time for 5 h, solid-liquid ratio for 1:30 g/mL). The extraction temperature was determined to be the primary factor influencing the extraction yield. The HCPS molecules had an average molecular weight of 8.854 × 103 kDa and were primarily of mannose (Man), rhamnose (Rha), glucuronic acid (GlcA), galacturonic acid (GalA), glucose (Glc), and xylose (Xyl). In addition, the backbone of the HCPS might consist of →6)-α-d-Glcp-(1→ and →6)-β-d-GalpA-(1→. The HCPS had no triple-helix structure. The scanning electron microscopy (SEM) results showed that the HCPS presented a smooth and uniform appearance, and some sheet and chain structures existed. Moreover, the HCPS exhibited significant anti-oxidant activity and inhibited the activity of α-amylase and α-glucosidase. These findings showed that HCPS might be developed into a potential material for hypoglycemia, and provides a reference for the development of Houttuynia cordata polysaccharide applications in food.

Effect of crude polysaccharide from seaweed, Dictyopteris divaricata (CDDP) on gut microbiota restoration and anti-diabetic activity in streptozotocin (STZ)-induced T1DM mice

Type-1 Diabetes Mellitus (T1DM) is regarded as a multifunctional, immune-related disease which causes massive destruction of islet β-cells in pancreas resulting in hyperglycemic, hypoinsulinemia and hyperlipidimic conditions. The aim of the present study, was to investigate the hypothesis that streptozotocin (STZ)-induced T1DM in Balb/c mice when treated with crude polysaccharide from seaweed, Dictyopteris divaricata (CDDP) depicts improvement in diabetes-related symptoms. Treatment with CDDP resulted in decreased body weight loss, improved food consumption and water intake disbalances. The CDDP effectively improved fasting blood glucose, oral glucose tolerance (OGTT), serum insulin, insulin secretion, rejuvenation of β-cells mass, serum lipid profile and pro-inflammatory cytokines levels. Additionally, treatment with CDDP increased the population of beneficial bacteria such as Firmicutes, Bacteroidetes and Lactobacillus at phylum, family and genus levels by 16S rRNA sequencing. Furthermore, immunohistological examination confirmed that CDDP reduces the inflammation and restored the structural morphology of colon and upraised the levels of insulin receptor substrate-1 (IRS-1), Mucin-2 (MUC-2) and tight-junction proteins (TJs) whereby maintaining the gut structures and barrier permeability. Thus, the above presented data, highlights the safe and therapeutic effects of crude polysaccharide (CDDP) from D. divaricata in the treatment and restoration of T1DM disorders and can be used as a food supplement alternative to diabetes medicine.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

The Characterization and Functional Properties of Euglena gracilis Paramylon Treated with Different Methods

Euglena gracilis paramylon (EGP) is a polymeric polysaccharide composed of linear β-1,3 glucan. The water insolubility of EGP severely limits its application. This work aimed to improve the functional characteristics of EGP by hydrogen peroxide (H₂O₂) degradation and carboxymethylated modification. The results showed that the crystallinity of EGP degraded by H₂O₂ and carboxymethylated modification decreased by 14% and 46%, and the thermal degradation temperature was significantly descending in a crystallinity-dependent manner. In addition, the results showed that H₂O₂ degradation and carboxymethylation significantly improved the adsorption capacity of EGP for oil, dyes, and metal ions, and their water solubility increased by 9% and 85%. This result will provide a valuable theoretical basis for the development and utilization of EGP.

Characterization and Antibacterial Activities of Carboxymethylated Paramylon from Euglena gracilis

Paramylon from Euglena gracilis (EGP) is a polymeric polysaccharide composed of linear β-1,3 glucan. EGP has been proved to have antibacterial activity, but its effect is weak due to its water insolubility and high crystallinity. In order to change this deficiency, this experiment carried out carboxymethylated modification of EGP. Three carboxymethylated derivatives, C-EGP1, C-EGP2, and C-EGP3, with a degree of substitution (DS) of 0.14, 0.55, and 0.78, respectively, were synthesized by varying reaction conditions, such as the mass of chloroacetic acid and temperature. Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR) analysis confirmed the success of the carboxymethylated modification. The Congo red (CR) experiment, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetry (TG) were used to study the conformation, surface morphology, crystalline nature, and thermostability of the carboxymethylated EGP. The results showed that carboxymethylation did not change the triple helix structure of the EGP, but that the fundamental particles’ surface morphology was destroyed, and the crystallization area and thermal stability decreased obviously. In addition, the water solubility test and antibacterial experiment showed that the water solubility and antibacterial activity of the EGP after carboxymethylation were obviously improved, and that the water solubility of C-EGP1, C-EGP2, and C-EGP3 increased by 53.31%, 75.52%, and 80.96% respectively. The antibacterial test indicated that C-EGP3 had the best effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with minimum inhibitory concentration (MIC) values of 12.50 mg/mL and 6.25 mg/mL. The diameters of the inhibition zone of C-EGP3 on E. coli and S. aureus were 11.24 ± 0.15 mm and 12.05 ± 0.09 mm, and the antibacterial rate increased by 41.33% and 43.67%.

Comparison on Bioactivities and Characteristics of Polysaccharides From Four Varieties of Gastrodia elata Blume

The composition, physicochemical properties, in vitro biological activity, and hypoglycemic activity exhibited by polysaccharides from four varieties of G. elata were investigated in this study; the four extracted GaE polysaccharides were termed as GaE-B (G. elata Bl. f. glauca S. chow polysaccharides), GaE-R (G. elata Bl. f. elata polysaccharides), GaE-Hyb (hybridization of G. elata Bl. f. glauca S. chow and G. elata Bl. f. elata polysaccharides), and GaE-G (G. elata Bl. f. viridis Makino polysaccharides). As revealed by the results, the GaE polysaccharides were found with the same monosaccharide composition, primarily including glucose, whereas the content of each variety was significantly different. In addition, different degrees of differences were found in the in vitro antioxidant and hypoglycemic activity, molecular weight, yield, and chemical composition exhibited by the abovementioned varieties. However, GaE-B and GaE-Hyb were found with similar physical properties, chemical composition, and antioxidant and hypoglycemic activity. GaE-R had the lowest yield, total sugar content, and molecular weight, whereas it involved higher xylose, binding protein, and polyphenols as well as higher antioxidant and hypoglycemic activity. In contrast, GaE-G was found with the highest yield, total sugar content, and molecular weight, whereas it contained the lowest xylose, binding protein, and polyphenols, as well as the weakest antioxidant and hypoglycemic activity. In brief, the polysaccharide of G. elata, a plant resource for homology of medicine and food, could more significantly enhance the biological activity of G. elata as it was released in the process of decocting and stewing. To be specific, the assessment of polysaccharide activity alone suggested that GaE-R was the best.

Interaction between nanometer calcium oxalate and renal epithelial cells repaired with carboxymethylated polysaccharides

OBJECTIVE

Injury of renal tubular epithelial cells (HK-2) is an important cause of kidney stone formation. In this article, the repairing effect of polysaccharide (PCP0) extracted from the traditional Chinese medicine Poria cocos and its carboxymethylated derivatives on damaged HK-2 cells was studied, and the differences in adhesion and endocytosis of the cells to nanometer calcium oxalate monohydrate (COM) before and after repair were explored.

METHODS

Sodium oxalate (2.8 mmol/L) was used to damage HK-2 cells to establish a damage model, and then Poria cocos polysaccharides (PCPs) with different carboxyl (COOH) contents were used to repair the damaged cells. The changes in the biochemical indicators of the cells before and after the repair and the changes in the ability to adhere to and internalize nano-COM were detected.

RESULTS

The natural PCPs (PCP0, COOH content = 2.56%) were carboxymethylated, and three carboxylated modified Poria cocos with 7.48% (PCP1), 12.07% (PCP2), and 17.18% (PCP3) COOH contents were obtained. PCPs could repair the damaged HK-2 cells, and the cell viability was enhanced after repair. The cell morphology was gradually repaired, the proliferation and healing rate were increased. The ROS production was reduced, and the polarity of the mitochondrial membrane potential was restored. The level of intracellular Ca²⁺ ions decreased, and the autophagy response was weakened.

CONCLUSION

The cells repaired by PCPs inhibited the adhesion to nano-COM and simultaneously promoted the endocytosis of nano-COM. The endocytic crystals mainly accumulated in the lysosome. Inhibiting adhesion and increasing endocytosis could reduce the nucleation, growth, and aggregation of cell surface crystals, thereby inhibiting the formation of kidney stones. With the increase of COOH content in PCPs, its ability to repair damaged cells, inhibit crystal adhesion, and promote crystal endocytosis all increased, that is, PCP3 with the highest COOH content showed the best ability to inhibit stone formation.

Evaluation of the biological activities of β-glucan isolated from Lentinula edodes

Lentinula edodes (shiitake) is an edible mushroom that contains many constituents and β-glucan is considered a major polysaccharide. This study, therefore, aimed to characterize β-glucan and evaluate its activities. Fresh fruit bodies of L. edodes were used for β-glucan extraction and followed by analyses via Fourier transform infrared, Nuclear magnetic resonance, and High Performance Liquid Chromatography confirming its characteristic structure. For evaluating biological activities of β-glucan, different concentrations (0.1-3.5 mg ml^-1 ) were assessed. The optimal dose was 3.5 mg ml^-1 that showed the highest scavenging radical ability (75.3%) confirms antioxidant activity, strong inhibition of the peroxyl radical (80.9%) to inhibit lipid peroxidation, elevation the inhibition percentage of both α-amylase (73.4%) and α-glucosidase (70.3%) indicates the antidiabetic properties, and highest AFB1 reduction (88%) which ensured the aflatoxin-detoxifying ability. In addition, antifungal activity of β-glucan was evaluated to inhibit sporulation process in Aspergillus niger and recorded with minimum inhibitory concentration of 2.5 mg ml^-1 and minimum fungicidal concentration of 3 mg ml^-1 . In a dose-dependent manner, higher concentration of β-glucan affects viability of tumor cells concomitant induces potent anti-cancer immune responses and inhibited the activity of topoisomerase I which are considered an important target for cancer chemotherapy. Therefore, L. edodes-β-glucan has the potential to act as a suggestive agent for antioxidant, antidiabetic, antifungal activity, and aflatoxin detoxification.

Structural characterization and in vitro hypoglycaemic activity of glucomannan from Anemarrhena asphodeloides Bunge

A new polysaccharide (AABP-2B) was obtained from Anemarrhena asphodeloides Bunge after purification by gradient alcohol precipitation and DEAE-52 cellulose column chromatography. AABP-2B was confirmed to be a homogeneous polysaccharide with a molecular weight of 5800 Da and was composed of mannose and glucose at a molar ratio of 7.2 : 2.8. Structural analysis demonstrated that the backbone of AABP-2B was mainly composed of 4)-β-D-Manp-(1, 4,6)-β-D-Glcp-(1 and 3,6)-β-D-Manp-(1. The hypoglycaemic effect of AABP-2B was evaluated by its inhibition of α-glucosidase activities and insulin resistance in a HepG2 cell model. The results showed that AABP-2B displayed α-glucosidase inhibitory activities and could significantly improve glucose consumption by activating the IRS-1/PI3K/Akt signalling pathway in insulin-resistant HepG2 cells. Hence, AABP-2B may have potential as a functional food or medicine for diabetes therapy.

Preparation and structural properties of selenium modified heteropolysaccharide from the fruits of Akebia quinata and in vitro and in vivo antitumor activity

Cancer is a complex disease, and blocking tumor angiogenesis has become one of the most promising approaches in cancer therapy. Here, an exopoly heteropolysaccharide (AQP70-2B) was firstly isolated from Akebia quinata. Monosaccharide composition indicated that the AQP70-2B was composed of rhamnose, glucose, galactose, and arabinose. The backbone of AQP70-2B consisted of →1)-l-Araf, →3)-l-Araf-(1→, →5)-l-Araf-(1→, →3,5)-l-Araf-(1→, →2,5)-l-Araf-(1→, →4)-d-Glcp-(1→, →6)-d-Galp-(1→, and →1)-d-Rhap residues. Based on the close relationship between selenium and anti-tumor activity, AQP70-2B was modified with selenium to obtain selenized polysaccharide Se-AQP70-2B. Then, a series of methods for analysis and characterization, especially scanning electron microscopy coupled with energy dispersive spectrometry (SEM-EDS), indicated that Se-AQP70-2B was successfully synthesized. Furthermore, zebrafish xenografts and anti-angiogenesis experiments indicated that selenization could improve the antitumor activity by inhibiting tumor cell proliferation and migration and blocking angiogenesis.

Spheroidization of ultrasonic degraded corn silk polysaccharide to enhance bioactivity by the anti-solvent precipitation method

BACKGROUND

Corn silk is a very important by-product of corn production with medicinal value. Corn silk polysaccharide (CSP) is the main active ingredient. In the present study, ultrasound and spheroidization by anti-solvent were applied to improve the biological activity of CSP.

RESULTS

The results showed that ultrasonic degradation improved the α-glucosidase inhibitory activity of CSP by changing its physicochemical characteristics. As the anti-solvent ratio increased, the particle size of the nanoparticles (NPs) from the spheroidization of ultrasonic-degraded corn silk polysaccharide (UCSP) gradually increased, and NP-1 exhibited the highest inhibitory effect of α-glucosidase. Isothermal titration calorimetry (ITC) results indicated that the enhanced activity might be due to more α-glucosidase binding sites with NP-1 compared with no spheroidization. Western blotting results showed that NP-1 could improve the 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-d-glucose (2-NBDG) uptake in the L6 cells by regulating the phosphatidylinositol 3-kinase (PI3K)/Akt signal pathway and the translocation of glucose transporter 4 (GLUT4). NP-1 also exhibited excellent stability in different environments.

CONCLUSION

The study revealed that ultrasonic treatment and spheroidization processing showed potential applications for improving the biological activity of polysaccharides. © 2021 Society of Chemical Industry.

Effects of Lactobacillus plantarum Fermentation on the Chemical Structure and Antioxidant Activity of Polysaccharides from Bulbs of Lanzhou Lily

Recently, Lanzhou lily has attracted more attention because of its bioactive components specifically polysaccharides. We studied in vitro the effects of Lactobacillus plantarum fermentation on the physicochemical properties, chemical structure, and antioxidant activity of the Lanzhou lily polysaccharide. The results showed that compared with the unfermented Lanzhou lily polysaccharide (LP-W), the molecular weight (M _w) of the fermented Lanzhou lily polysaccharide (LPF-W) decreased from 4334 to 1684 kDa, the particle size decreased from 300.8 ± 6.38 to 141.9 ± 4.96 nm, and the solubility increased from 72.33 ± 3.58 to 104.27 ± 2.91 mg/mL. In addition, after fermentation, the monosaccharide composition of LPF-W changed, and the alternation of mannose residues and glucose residues disappeared. The results of the analysis of the antioxidant activity in vitro showed that compared with LP-W, the fermented LPF-W had higher DPPH radical ability, superoxide anion radical scavenging ability, and reducing efficiency, but the hydroxyl radical scavenging ability decreased. These findings provide a reference for the potential application of the lily polysaccharide as a plant-derived antioxidant in functional foods.

Effect of Fe (III), Zn (II), and Cr (III) complexation on the physicochemical properties and bioactivities of corn silk polysaccharide

In this paper, Fe (III), Zn (II), and Cr (III) were used to complex with corn silk polysaccharide (CSP) by classical methods and CSP-Fe, CSP-Zn, and CSP-Cr were successfully synthesized, respectively. The physicochemical properties and structural features were characterized by chemical composition analysis, inductive coupled plasma-mass spectrometry (ICP-MS), ultraviolet-visible (UV-Vis) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, fourier transform infrared (FT-IR) spectroscopy, circular dichroism (CD) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC), respectively. The antioxidant activities and inhibitory effects on α-glucosidase of CSP, CSP-Fe, CSP-Zn, and CSP-Cr were compared. The results showed that the Fe (III), Zn (II), and Cr (III) chelation could change the morphology, conformation, thermostability, and biological activities of CSP. CSP-Zn exhibited higher antioxidant activities and inhibition effects on α-glucosidase than CSP, which suggested that it could be considered as a potential candidate for developing an ingredient of functional foods for antidiabetics.

Extraction Optimization of Polysaccharides From Corn Silk and Their Antioxidant Activities in vitro and in vivo

Response surface technique was employed for improving the extraction of corn silk polysaccharides (CSP). Temperature, liquid-to-solid ratio, and per extraction time were all examined as separate factors. The optimal extraction parameters were determined by fitting experimental data to a second-order polynomial; a liquid-to-solid ratio of 21.5 ml/g, temperature equivalent to 88°C, and extraction time of 1.87 h. The experimental yield of the extracted polysaccharides following the application of these conditions was 4.33 ± 0.08% (dry weight), which fit quite well with the predicted value. CSP’s strong scavenging capabilities against hydroxyls, 1,1-diphenyl-2-picrylhydrazyl radicals, and superoxide anions along with its excellent reducing potential, were demonstrated in an in vitro antioxidant experiment. Meanwhile, in vivo testing revealed that CSP substantially enhanced glutathione peroxidase and superoxide dismutase activities. The Malondialdehyde levels in the liver and serum of aged mice also underwent a decrease. This study found that CSP has a substantial antioxidant potential in vitro and in vivo, suggesting that it might be used as an antioxidant in food and medicine.

Antioxidant activity of sulfated Porphyra yezoensis polysaccharides and their regulating effect on calcium oxalate crystal growth

The nucleation, growth and aggregation of calcium oxalate (CaOx) crystals and the oxidative damage of renal tubular epithelial cells are the key factors to induce kidney stones. In this study, degraded Porphyra yezoensis polysaccharide (PYP0) with 14.14% sulfate group (-OSO₃^-) content was modified via the sulfur trioxide-pyridine method to obtain three kinds of sulfated P. yezoensis polysaccharides (PYPs), namely, PYPS1, PYPS2, and PYPS3, with -OSO₃^- group contents of 17.11%, 20.28%, and 27.14% respectively. Fourier transform infrared spectroscopy, ¹H NMR, and ¹³C NMR analyses showed that the -OSO₃^- groups replaced the hydroxyl groups at the C2, C4, and C6 positions on (1 → 3)-linked β-D-galactose, the basic structural skeleton unit of PYP0. The antioxidant activity of the PYPSs increased after sulfation, and their scavenging capacity for OH and DPPH free radicals was enhanced with the increase in their -OSO₃^- group content. Calcium oxalate (CaOx) crystal growth experiments showed that sulfated PYPs promoted the conversion of the thermodynamically stable and sharp CaOx monohydrate (COM) crystals into the thermodynamically unstable and round CaOx dihydrate crystals. With the increase in the -OSO₃^- group content of the polysaccharides, the concentration of soluble Ca²⁺ ions in the supernatant increased and the amount of CaOx precipitate decreased. PYPs were nontoxic to human kidney proximal tubular epithelial cells (HK-2) and could protect HK-2 from oxidative damage caused by nano-COM and reduce the level of reactive oxygen species in cells. PYPS3, which had the highest degree of sulfation, had the best protective capability. The results of this work showed that sulfation improved the biological activity of PYPs. This study could provide inspiration for the development of new drugs for the prevention and treatment of kidney stones.

Carboxymethylation of Corn Silk Polysaccharide and Its Inhibition on Adhesion of Nanocalcium Oxalate Crystals to Damaged Renal Epithelial Cells

The purpose of this study was to explore the repair effect of carboxymethyl-modified corn silk polysaccharide (CSP) on oxidatively damaged renal epithelial cells and the difference in adhesion between cells and calcium oxalate crystals. The CSP was degraded and modified through carboxymethylation. An oxidatively damaged cell model was constructed by oxalate damage to human kidney proximal tubular epithelial (HK-2) cells. Then, the damaged cells were repaired by modified polysaccharides, and the changes in biochemical indexes and adhesion ability between cells and crystals before and after repair were detected. Four modified polysaccharides with carboxyl group (-COOH) contents of 3.92% (CSP0), 7.75% (CCSP1), 12.90% (CCSP2), and 16.38% (CCSP3) were obtained. Compared with CSP0, CCSPs had stronger antioxidant activity, could repair damaged HK-2 cells, and could reduce phosphorylated serine eversion on the cell membrane, the expression of osteopontin (OPN) and Annexin A1, and crystal adhesion. However, its effect on the expression of hyaluronic acid synthase was not substantial. The carboxymethyl modification of the CSP can improve its ability to repair cells and inhibit crystal adhesion and aggregation. A high carboxymethylation degree results in strong polysaccharide activity. CCSPs are expected to reduce the risk of kidney stone formation and recurrence.

Effects of different chemical modifications on the structure and biological activities of polysaccharides from Orchis chusua D. Don

In this study, an enzyme-assisted extraction method was used to extract Orchis chusua D. Don (Salep) polysaccharide (SP), which was then modified by sulfation, acetylation, phosphorylation, and carboxymethylation to obtain modified polysaccharides. Furthermore, their degree of substitution, chemical composition, and molecular weight were evaluated. The primary structural features were characterized by UV spectra, FT-IR spectra, Congo-red test, and scanning electron microscope. The phosphorylated polysaccharide (SP-P) was demonstrated the highest scavenging ability on hydroxyl radical and growth-promoting activity on Lactobacillus Bulgaricus. The carboxymethylated polysaccharide (SP-C) was exhibited the strongest DPPH and ABTS radical scavenging effects. The acetylated polysaccharide (SP-A) displayed the best proliferation effects on Bifidobacterium adolescentis, whereas the sulfated polysaccharide (SP-S) maintained moderately stable antioxidant and probiotic ability. These findings indicate that the modified polysaccharides had their potential significance as new antioxidants and probiotics for the food industry. PRACTICAL APPLICATION: This article provides a new source for the development of polysaccharide derivatives as new antioxidants and probiotics for the food industry.

Ultrasound-Assisted Extraction of Water-Soluble Polysaccharides from the Fruit of Acanthopanaxbrachypus: Physicochemical, Structural and Functional Properties

The ultrasound-assisted extraction (UAE) parameters of total water-soluble polysaccharides (TABPs) from Acanthopanaxbrachypus fruit were optimized by Box-Behnken design (BBD) and response surface methodology (RSM). Physicochemical, structural, and functional properties of TABPs were investigated by chemical analysis, inductively coupled plasma optical emission spectrometry (ICP-OES), high performance liquid chromatography (HPLC), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), water-holding capacity (WHC), oil-holding capacity (OHC), emulsion capacity (EC), emulsion stability (ES), as well as DPPH^. and ABTS^.+ scavenging assays. The results showed that the maximal UAE-yield of TABPs was 3.81±0.18 % under the optimal conditions (ultrasonic power 325 W, extraction temperature 47 °C, extraction time 22 min). TABPs was rich in some beneficial element (Mg, K, Fe, Zn and Na) but little in harmful elements (Hg, Cd, As and Pb), and displayed rough surface with flake-like features and large dents, contained 93.89±0.08 % of total carbohydrate with more different monosaccharides including glucose, galactose, rhamnose, arabinose, mannose, xylose, and uronic acid in a molar ratio of 8.83 : 7.90 : 4.74 : 4.55 : 2.80 : 2.39 : 1.00, respectively. TABPs exhibited broad weight distribution (11.2-133.5 kDa), excellent thermal stability (>280 °C), WHC (0.61±0.08 g water/g sample) and OHC (4.53±0.12 g oil/g sample), as well as higher EC (43.75±1.23 %) and ES (38.32±1.50 %). Furthermore, TABPs also displayed remarkable scavenging activities on DPPH^. and ABTS^.+ in vitro. These findings provide a scientific basis for the applications of TABPs in functional additives for food, medicine, and cosmetics.

Structural elucidation of three novel oligosaccharides from Kunlun Chrysanthemum flower tea and their bioactivities

Coreopsis tinctoria is commonly called Kunlun Chrysanthemum and a plateau plant with tremendous commercial value in functional tea and medicinal applications. In folk medicine, Kunlun Chrysanthemum flower is often used as an adjunctive therapy for diabetes and Alzheimer's disease. To further explore the chemicals responsible for the health benefits of Kunlun Chrysanthemum flowers, three homogeneous oligosaccharides, CT70-1A, CT70-1B and CT70-2 were isolated, and their detailed structures were determined from chemical and spectral analyses. The three oligosaccharides were composed of glucose, mannose, galactose, and arabinose in different ratios. They showed dose-dependent α-amylase and α-glucosidase inhibitory effects. In addition, they showed NO production inhibitory activities in BV2 cells, with IC₅₀ values of 0.23, 0.24 and 0.27 mM, respectively. Taken together, these results suggested that Kunlun Chrysanthemum oligosaccharides might ameliorate hyperglycemia and neuroinflammation, which could prevent the development of diseases such as type 2 diabetes and Alzheimer's disease. This study provides chemical and bioactive perspectives that support the consumption of Kunlun Chrysanthemum flower tea for health benefits.

Medicinal plants utilized in Thai Traditional Medicine for diabetes treatment: Ethnobotanical surveys, scientific evidence and phytochemicals

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus remains the most lethal metabolic disease of contemporaneous times and despite the therapeutic arsenal currently available, research on new antidiabetic agents remains a priority. In recent years, the revitalization of Thai Traditional Medicine (TTM) became a clear priority for the Thai government, and many efforts have been undertaken to accelerate research on herbal medicines and their use in medical services in various hospitals. Additionally, and particularly in rural areas, treatment of diabetes and associated symptomatology frequently relies on herbal preparations recommended by practitioners of TTM. In the current work, medicinal plants used in Thailand for treating diabetes, as well as their hypoglycaemic pharmacological evidences and potential therapeutic use for diabetes-related complications were reviewed.

MATERIALS AND METHODS

Ethnopharmacological information on the plant materials used in TTM for diabetes treatment was collected through literature search in a range of scientific databases using the search terms: diabetes, folk medicine, Thailand medicinal plants, traditional medicine. Information regarding scientific evidence on the antidiabetic effects of surveyed species was obtained considering not only the most common taxonomic designation, but also taxonomic synonyms, and including the keywords 'diabetes' and 'hypoglycaemic effect'.

RESULTS

A total of 183 species known to be used for diabetes management in TTM were reviewed, with 30% of them still lacking experimental evidences to support claims regarding the mechanisms and phytochemicals underlying their antidiabetic properties. Moreover, a total of 46 bioactives displaying effective antidiabetic effects have been isolated from 24 species, their underlying mechanism(s) of action being fully or partially disclosed.

CONCLUSIONS

We deliver the most extensive survey dealing with the ethnomedicinal knowledge of Thai medicinal plants utilized on diabetes management. We are certain that the current review will spark further research on Thai plants for the development of new standardized phytomedicines through drug discovery programmes.

A Novel Optimization of Water-Soluble Compound Polysaccharides from Chinese Herbal Medicines by Quantitative Theory and Study on Its Characterization and Antioxidant Activities

The present study optimized the extraction characterization and antioxidant activities of water-soluble compound polysaccharides (CPs) from hawthorn, lotus leaf, Fagopyrum tataricum, semen cassiae, Lycium barbarum, and Poria cocos Chinese herbal medicines that have mass ratios of 4 : 2 : 2 : 1.5 : 1 : 1. The CPs yield equation was predicted using quantitative theory, to which a maximum CPs yield of 7.18±0.24 % under the following optimal extraction conditions: a water-to-raw material ratio of 30 mL/g, an extraction temperature of 65 °C, an extraction time of 45 min, and extraction mode ultrasonic-assistant extraction. CPs were consisted of Ara, Gal, Glc, Xyl, Man, GalA and GlcA in a molar ratio of 3.1 : 2.6 : 50.6 : 1.7 : 20.4 : 17.2 : 4.2. The HPGPC profiles and FT-IR spectra implied that CPs were heterogeneous acidic polysaccharides and possessed the β-d-pyranose configuration. Congo red test, CD spectrum and SEM revealed that CPs with three helix conformation showed a flocculent, granulous or sheet-like appearance. Furthermore, the relationships between antioxidant activity and concentration of CPs displayed significant positive correlation, and the scavenging abilities for DPPH, hydroxyl radical, ABTS, superoxide-anion radical and reducing power of CPs were 93.56±2.51 %, 84.03±1.69 %, 83.29±1.93 %, 37.49±1.93 % and 0.467±0.006 at a concentration of 4.0 mg/mL. Therefore, CPs could be applied as a potential natural antioxidant in pharmaceutical or functional food fields.

Inhibitors of α-amylase and α-glucosidase: Potential linkage for whole cereal foods on prevention of hyperglycemia

The strategy of reducing carbohydrate digestibility by controlling the activity of two hydrolyzing enzymes (α-amylase and α-glucosidase) to control postprandial hyperglycemia is considered as a viable prophylactic treatment of type 2 diabetes mellitus (T2DM). Thus, the consumption of foods rich in hydrolyzing enzyme inhibitors is recommended for diet therapy of diabetes. Whole cereal products have gained increasing interests for plasma glucose-reducing effects. However, the mechanisms for whole cereal benefits in relation to T2DM are not yet fully understood, but most likely involve bioactive components. Cereal-derived phenolic compounds, peptides, nonstarch polysaccharides, and lipids have been shown to inhibit α-amylase and α-glucosidase activities. These hydrolyzing enzyme inhibitors seem to make whole cereals become nutritional strategies in managing postmeal glucose for T2DM. This review presents an updated overview on the effects provided by cereal-derived ingredients on carbohydrate digestibility. It suggests that there is some evidence for whole cereal intake to be beneficial in amelioration of T2DM through inhibiting α-glucosidase and α-amylase activities.

Gallic Acid-Laminarin Conjugate Is a Better Antioxidant than Sulfated or Carboxylated Laminarin

A 12.4 kDa laminarin (LM) composed of β(1→3)-glucan with β(1→6)-branches was extracted from brown seaweed Lobophora variegata and modified via carboxylation using dielectric barrier discharge (LMC), conjugation with gallic acid (LMG), and sulfation (LMS). Analyses of the chemical composition of LMC, LMG, and LMS yielded 11.7% carboxyl groups, 1.5% gallic acid, and 1.4% sulfate content, respectively. Antioxidant activities of native and modified laminarins were assessed using six different in vitro methods. Sulfation stopped the antioxidant activities of LM. On the other hand, carboxylation improved cooper chelation (1.2 times). LMG was found to be a more efficient antioxidant agent than LM in terms of copper chelation (1.3 times), reducing power (1.3 times), and total antioxidant capacity (80 times). Gallic acid conjugation was further confirmed using Fourier transform infrared spectroscopy (FT-IR) and one- and two-dimensional NMR spectroscopy analyses. LMG also did not induce cell death or affect the cell cycle of Madin–Darby canine kidney (MDCK) cells. On the contrary, LMG protected MDCK cells from H₂O₂-induced oxidative damage. Taken together, these results show that LMG has the potent antioxidant capacity, and, therefore, potential applications in pharmacological and functional food products.

Carboxymethylation of polysaccharides: Synthesis and bioactivities

Polysaccharides are a structurally diverse class of biomolecules with a wide variety of bioactivities. Natural polysaccharides isolated from plants and fungi are used as raw materials in food and pharmaceutical industries due to their therapeutic properties, non-toxicity, and negligible side effects, but many natural polysaccharides possess low bioactivities when compared to synthetic medicines due to their structure and physicochemical properties. Literature studies revealed that carboxymethylation of polysaccharides enhances the bioactivities and water solubility of native polysaccharides significantly, and provide structural diversity and even the addition of new bioactivities. This review article mainly focuses on the recent research on carboxymethylation of polysaccharides including preparation, characterization, and bioactivities. This article also throws light on future directions and scope to develop new carboxymethylated polysaccharide derivatives for many industries such as food processing, cosmetics, nutraceuticals, and pharmaceutical industry.

Structural characterization and hypoglycemic activity of an intracellular polysaccharide from Sanghuangporus sanghuang mycelia

A neutral polysaccharide (SSIPS1) was isolated and purified from cultured mycelia of Sanghuangporus sanghuang by DEAE Sepharose Fast Flow and Sephacryl S-100 columns. Basic monosaccharide composition indicated that SSIPS1 was mainly composed of d-glucose. The results of methylation and 2D-NMR analysis suggested that the glycosidic linkages of SSIPS1 were elucidated to consisted of 1,4-linked α-d-glucopyranose (Glcp) residues with two branched points at O-6. The two branches were composed of 1,4-linked α-D-Glcp terminated with α-D-Glcp, 1,4-linked α-D-Glcp and 1,4-linked β-Galp terminated by α-D-Glcp. Moreover, its chain conformation was revealed to present a flexible chain conformation in 0.1 NaNO₃ with a hydrodynamic radius and radius of gyration of 3.26 and 6.45 nm by multi-angle laser light scattering, with a single chain of 0.559 nm observed by atomic force microscopy. Further, SSIPS1 exhibited a potential inhibitory activity against α-amylase and α-glucosidase, and it had hypoglycemic effects on in vitro insulin resistance of HepG2 cells as well.

Modulation of Calcium Oxalate Crystal Growth and Protection from Oxidatively Damaged Renal Epithelial Cells of Corn Silk Polysaccharides with Different Molecular Weights

Corn silk polysaccharide (CSP0; molecular weight = 124 kDa) was degraded by ultrasonication to obtain five degraded polysaccharides, namely, CSP1, CSP2, CSP3, CSP4, and CSP5, with molecular weights of 26.1, 12.2, 6.0, 3.5, and 2.0 kDa, respectively. The structures of these polysaccharides were characterized by FT-IR, 1H NMR, and 13C NMR analyses. The antioxidant activities, including scavenging ability for hydroxyl radicals and DPPH free radicals, chelation ability for Fe2+ ions, and reducing ability of CSP increased with decreased molecular weight of CSPs within 6.0 to 124 kDa. However, antioxidant activity weakened when the molecular weight of CSPs reached 3.5 and 2 kDa. CSP3 with a molecular weight of 6.0 kDa exhibited the strongest antioxidant activity. After protection with 60 μg/mL CSPs, the viability of human renal proximal tubular epithelial cells (HK-2) damaged by nano-COM crystals increased, the level of reactive oxygen species decreased, and the amount of COM crystal adhered onto the cell surface decreased. The ability of CSPs to protect cells from CaOx crystal damage was consistent with their antioxidant activity. CSPs can specifically combine with CaOx crystal to inhibit the conversion of calcium oxalate dihydrate crystal to calcium oxalate monohydrate crystal. All these results showed that the activity of CSPs was closely correlated with molecular weight. A very high or low molecular weight of CSPs was not conducive to their activity. CSPs, especially CSP3 with a molecular weight of 6.0 kDa, can be used as a potential antistone drug.