Carboxymethylation and acetylation of the polysaccharide from Cordyceps militaris and their α-glucosidase inhibitory activities

Effects of different chemical modifications on physicochemical and antioxidation properties of Lycium barbarum seed dreg polysaccharides

Recent studies have witnessed that chemical modification can improve the physicochemical and functional properties of plants' polysaccharides. Herein, we modified the natural Lycium barbarum seed dreg polysaccharides (LBSDPs) by sulfation (S-LBSDPs), phosphorylation (P-LBSDPs), and carboxymethylation (C-LBSDPs), and evaluated the chemical composition and antioxidant activity of their derivatives. Natural polysaccharides and their derivatives exhibited typical polysaccharide absorption peaks and characteristic group absorption peaks in FT-IR spectra along with maximum UV absorption. After modification, the total sugar and protein contents of the derivatives were decreased, whereas the uronic acid content was increased. Among the three derivatives, sulfated polysaccharides displayed excellent thermal stability. S-LBSDP and P-LBSDP showed the highest ABTS radical scavenging and reducing power while S-LBSDPs and C-LBSDPs showed better DPPH radical scavenging effect, and P-LBSDPs showed considerable Fe2+ chelating ability. Our data indicate that chemical modifications can impart a positive effect on the antioxidant potential of plant-derived polysaccharides.

Preparation for shaddock skin polysaccharide derivatives by response surface method

The derivation of polysaccharide has an important impact on its properties. The preparation process of phosphorylated-shaddock skin polysaccharides (SSP) and acetylated-SSP was optimized by the response surface method. The constructed model was accurate and reliable in predicting the substitution of acetylated-SSP and the phosphate content of phosphorylated-SSP. This method was simple and easy to operate, which provided a basis for the preparation of a large number of derivatives.

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.

The function and application of edible fungal polysaccharides

Edible fungi, commonly known as mushrooms, are precious medicinal and edible homologous gifts from nature to us. Edible fungal polysaccharides (EFPs) are a variety of bioactive macromolecular which isolated from fruiting bodies, mycelia or fermentation broths of edible or medicinal fungus. Increasing researches have confirmed that EFPs possess multiple biological activities both in vitro and in vivo settings, including antioxidant, antiviral, anti-inflammatory, immunomodulatory, anti-tumor, hypoglycemic, hypolipidemic, and regulating intestinal flora activities. As a result, they have emerged as a prominent focus in the healthcare, pharmaceutical, and cosmetic industries. Fungal EFPs have safe, non-toxic, biodegradable, and biocompatible properties with low immunogenicity, bioadhesion ability, and antibacterial activities, presenting diverse potential applications in the food industries, cosmetic, biomedical, packaging, and new materials. Moreover, varying raw materials, extraction, purification, chemical modification methods, and culture conditions can result in variances in the structure and biological activities of EFPs. The purpose of this review is to provide comprehensively and systematically organized information on the structure, modification, biological activities, and potential applications of EFPs to support their therapeutic effects and health functions. This review provides new insights and a theoretical basis for prospective investigations and advancements in EFPs in fields such as medicine, food, and new materials.

Research progress on the structure, derivatives, pharmacological activity, and drug carrier capacity of Chinese yam polysaccharides: A review

Chinese yam is a traditional Chinese medicine that has a long history of medicinal and edible usage in China and is widely utilised in food, medicine, animal husbandry, and other industries. Chinese yam polysaccharides (CYPs) are among the main active components of Chinese yam. In recent decades, CYPs have received considerable attention because of their remarkable biological activities, such as immunomodulatory, antitumour, hypoglycaemic, hypolipidaemic, antioxidative, anti-inflammatory, and bacteriostatic effects. The structure and chemical alterations of polysaccharides are the main factors affecting their biological activities. CYPs are potential drug carriers owing to their excellent biodegradability and biocompatibility. There is a considerable amount of research on CYPs; however, a systematic summary is lacking. This review summarises the structural characteristics, derivative synthesis, biological activities, and their usage as drug carriers, providing a basis for future research, development, and application of CYPs.

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.

Effects of Persimmon (Diospyros kaki L. cv. Mopan) Polysaccharide and Their Carboxymethylated Derivatives on Lactobacillus Strains Proliferation and Gut Microbiota: A Comparative Study

Persimmon is a fruit that contains sugars, vitamins, phenolic compounds, and various other nutrients. The aim of this study was to explore the structure of carboxymethylated persimmon polysaccharide (CM-PFP) and its interaction with the human gut microbiota. Carboxymethyl modification of the persimmon polysaccharide (PFP) increased both the Mw and Mn, enhanced dispersion stability, and decreased thermal stability. Both PFP and CM-PFP promoted the proliferation of Lactobacillus while inhibiting the proliferation of Staphylococcus aureus and Escherichia coli. In the simulated fecal fermentation, the pH of PFP- and CM-PFP-containing media decreased, the content of short-chain fatty acids increased, and the abundance of intestinal flora at the phylum and genus levels changed. The relative abundance of harmful intestinal bacteria was significantly reduced in both PFP and CM-PFP groups. Furthermore, it was found that CM-PFP was more easily metabolized than PFP, glucose, and fructo-oligosaccharide (FOS) and had a proliferation increase effect on Lactobacillus. Therefore, CM-PFP has a significant positive effect on both Lactobacillus proliferation and the human gut microbiota.

The effect of structure and preparation method on the bioactivity of polysaccharides from plants and fungi

Polysaccharides are not only the main components in the cell walls of plants and fungi, but also a structure that supports and protects cells. In the process of obtaining polysaccharides from raw materials containing cell walls, the polysaccharides on the cell walls are the products and also a factor that affects the extraction rate. Polysaccharides derived from plants and fungi have mild characteristics and exhibit various biological activities. The biological activity of polysaccharides is related to their chemical structure. This review summarizes the effects of the physicochemical properties and structure of polysaccharides, from cell walls in raw materials, that have an impact on their biological activities, including molecular weight, monosaccharide composition, chain structure, and uronic acid content. Also, the structure of certain natural polysaccharides limits their biological activity. Chemical modification and degradation of these structures can enhance the pharmacological properties of natural polysaccharides to a certain extent. At the same time, the processing method affects the structure and yield of polysaccharides on the cell wall and in the cell. The extraction and purification methods are summarized, and the effects of preparation methods on the structure and physiological effects of polysaccharides from plants and fungi are discussed.

Isolation, structures, bioactivities, application and future prospective for polysaccharides from Tremella aurantialba: A review

Since ancient times, Tremella aurantialba has been proposed to have medicinal and food benefits. Modern phytochemistry and pharmacological studies have demonstrated that polysaccharides, the main components from T. aurantialba appear to be an all-round talent resisting a variety of chronic inflammatory diseases and protecting against different types of tumors, diabetes and cardiovascular diseases. These health and pharmacological benefits have gained much attention from scholars around the world. Further, more and more methods for polysaccharides extraction, purification, structure identification have been proposed. Significantly, the bioactivity of fungus polysaccharides is affected by many factors such as extraction and purification conditions and chemical structure. This paper provides an overview of recent advances in the isolation, structural features and biological effects of polysaccharides derived from T. aurantialba, covers recent advances in the field and outlines future research and applications of these polysaccharides.

Recent advances in medicinal and edible homologous polysaccharides: Extraction, purification, structure, modification, and biological activities

110 kinds of traditional Chinese medicines can be used for medicine and food from Chinese pharmacopoeia in 2021. With the deepening of research in recent years, medicinal and edible homologous (MEH) traditional Chinese medicines have great development and application prospects in many fields. Polysaccharides are one of the major and representative pharmacologically active macromolecules in traditional Chinese medicines with MEH. Moreover, traditional Chinese medicines with MEH have become the main source of natural polysaccharides with safety, high efficiency, and low side effects. Increasing researches have confirmed that MEH polysaccharides (MEHPs) have multiple biological activities both in vitro and in vivo methods, such as antioxidant, immunomodulatory, anti-tumor, anti-aging, anti-inflammatory, hypoglycemic, hypolipidemic activities, and regulating intestinal flora. Additionally, different raw materials, extraction, purification, and chemical modification methods result in differences in the structure and biological activities of MEHPs. The purpose of the present review is to provide comprehensively and systematically reorganized information in the extraction, purification, structure, modification, biological activities, and potential mechanism of MEHPs to support their therapeutic effects and health functions. New valuable insights and theoretical basis for the future researches and developments regarding MEHPs were proposed in the fields of medicine and food.

Extraction, purification, structure, modification, and biological activity of traditional Chinese medicine polysaccharides: A review

Traditional Chinese medicines (TCM), as the unique natural resource, are rich in polysaccharides, polyphenols, proteins, amino acid, fats, vitamins, and other components. Hence, TCM have high medical and nutritional values. Polysaccharides are one of the most important active components in TCM. Growing reports have indicated that TCM polysaccharides (TCMPs) have various biological activities, such as antioxidant, anti-aging, immunomodulatory, hypoglycemic, hypolipidemic, anti-tumor, anti-inflammatory, and other activities. Hence, the research progresses and future prospects of TCMPs must be systematically reviewed to promote their better understanding. The aim of this review is to provide comprehensive and systematic recombinant information on the extraction, purification, structure, chemical modification, biological activities, and potential mechanism of TCMPs to support their therapeutic effects and health functions. The findings provide new valuable insights and theoretical basis for future research and development of TCMPs.

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%.

Structural Elucidation and Activities of Cordyceps militaris-Derived Polysaccharides: A Review

Cordyceps militaris is a parasitic edible fungus and has been used as tonics for centuries. Polysaccharides are a major water-soluble component of C. militaris. Recently, C. militaris-derived polysaccharides have been given much attention due to their various actions including antioxidant, anti-inflammatory, anti-tumor, anti-hyperlipidemic, anti-diabetic, anti-atherosclerotic, and immunomodulatory effects. These bioactivities are determined by the various structural characteristics of polysaccharides including monosaccharide composition, molecular weight, and glycosidic linkage. The widespread use of advanced analytical analysis tools has greatly improved the elucidation of the structural characteristics of C. militaris-derived polysaccharides. However, the methods for polysaccharide structural characterization and the latest findings related to C. militaris-derived polysaccharides, especially the potential structure-activity relationship, have not been well-summarized in recent reviews of the literature. This review will discuss the methods used in the elucidation of the structure of polysaccharides and structural characteristics as well as the signaling pathways modulated by C. militaris-derived polysaccharides. This article provides information useful for the development of C. militaris-derived polysaccharides as well as for investigating other medicinal polysaccharides.

Structural Elucidation, Modification, and Structure-Activity Relationship of Polysaccharides in Chinese Herbs: A Review

Chinese herbal polysaccharides (CHPs) are natural polymers composed of monosaccharides, which are widely found in Chinese herbs and work as one of the important active ingredients. Its biological activity is attributed to its complex chemical structure with diverse spatial conformations. However, the structural elucidation is the foundation but a bottleneck problem because the majority of CHPs are heteropolysaccharides with more complex structures. Similarly, the studies on the relationship between structure and function of CHPs are even more scarce. Therefore, this review summarizes the structure-activity relationship of CHPs. Meanwhile, we reviewed the structural elucidation strategies and some new progress especially in the advanced structural analysis methods. The characteristics and applicable scopes of various methods are compared to provide reference for selecting the most efficient method and developing new hyphenated techniques. Additionally, the principle structural modification methods of CHPs and their effects on activity are summarized. The shortcomings, potential breakthroughs, and developing directions of the study of CHPs are discussed. We hope to provide a reference for further research and promote the application of CHPs.

Carboxymethylation modification, characterization, antioxidant activity and anti-UVC ability of Sargassum fusiforme polysaccharide

Taking the degree of substitution (DS) as the index, the carboxymethylation conditions of Sargassum fusiforme polysaccharide (SFP) were studied. According to the single factor experiment results, the optimum experimental conditions were obtained: sodium hydroxide concentration, 15% (20 mL); alkalization temperature, 50 °C; dosage of chloroacetic acid 1.5 g; etherification time, 2 h, and the Carboxymethyl Sargassum fusiforme polysaccharide (CSFP) with the highest DS (0.635) was obtained. And then, the physicochemical properties, structural information and bioactivity of SFP and CSFP were characterized. The SFP and CSFP were composed of four monosaccharides, with a small amount of protein, and their molecular weights to 780.2 kDa and 386.3 kDa respectively. The results of FTIR and NMR showed that the carboxymethyl was successfully grafted onto the C-4 and C-6 of sugar chain. The results of anti UVC experiment showed that SFP and CSFP had a certain negative effect on cell activity, and the degree of damage caused by UVC radiation was weakened, and the anti UVC performance of CSFP was better than that of SFP.

Inhibition of Calcium Oxalate Formation and Antioxidant Activity of Carboxymethylated Poria cocos Polysaccharides

Three carboxymethylated Poria cocos polysaccharides (PCP-C1, PCP-C2, and PCP-C3) with -COOH contents of 6.13%, 10.24%, and 16.22%, respectively, were obtained by carboxymethylation of the original polysaccharide (PCP-C0), which has a molecular weight of 4 kDa and a carboxyl (-COOH) content of 2.54%. The structure of the PCP-Cs was characterized by FT-IR, ¹H NMR, and ¹³C NMR spectra. The four PCP-Cs exhibited antioxidant activity, and their ability to scavenge radicals (hydroxyl and DPPH) and chelate ferrous ions was positively correlated with the degree of carboxymethylation. As the content of -COOH groups in the PCP-Cs increases, their ability to regulate the growth of calcium oxalate (CaOx) crystals was enhanced, thus inhibiting the growth of calcium oxalate monohydrate (COM) crystals and inducing the formation of more calcium oxalate dihydrate (COD) crystals. The formed CaOx crystal was more round and blunt, the absolute value of the Zeta potential on the crystal surface increased, and the aggregation between crystals was inhibited. Thermogravimetric analysis curves showed that the proportions of PCP-C0, PCP-C1, PCP-C2, and PCP-C3 incorporated into the crystal were 20.52%, 15.60%, 10.65%, and 9.78%, respectively, in the presence of 0.4 g/L PCP-Cs. PCP-C protection resisted oxidative damages of human kidney proximal tubular epithelial cells (HK-2) caused by oxalate, resulting in increased cell viability and superoxide dismutase activity and decreased reactive oxygen species levels, malondialdehyde content, and 8-hydroxy-deoxyguanosine expression. Hence, PCP-Cs, especially PCP-C3, can inhibit the formation of CaOx crystals and may have the potential to be an alternative antistone drug.

Increased antioxidant activity and improved structural characterization of sulfuric acid-treated stepwise degraded polysaccharides from Pholiota nameko PN-01

The aim of this study was to investigate sulfuric acid degradation of the Pholiota nameko polysaccharide (AIPS-1). Three stepwise degraded polysaccharides (AIPS-2, AIPS-3, and AIPS-4) were obtained by sequentially increasing the strength of sulfuric acid treatment. Structural characterization showed that sulfuric acid treatment significantly decreased molecular weight, increased the content of uronic acid and changed the molar ratio of monosaccharide composition, while the major functional groups and the triple helical conformation of polysaccharides did not change significantly. In vitro experiments proved that the antioxidation ability of the stepwise degraded polysaccharides gradually increased (AIPS-1 < AIPS-2 < AIPS-3 < AIPS-4). An oxidative stress zebrafish model was established, which demonstrated that the ability of AIPS-3 and AIPS-4 to scavenge free radicals in zebrafish was significantly improved compared to AIPS-1. In conclusion, sulfuric acid treatment is an effective method for improving the antioxidant activity of polysaccharides, and increased antioxidant activity was closely related to the changes in their structural characteristics.

Extracellular polysaccharide biosynthesis in Cordyceps

Cordyceps is a parasitic edible fungus with a variety of metabolically active ingredients. The main active ingredient, extracellular polysaccharide (EPS), shows favourable application prospects in prevention and treatment of certain diseases. EPS extracted from different parts of various Cordyceps species can be used in health foods or medicinal preparations because of the structural diversity and multiple bioactivities. In terms of the complexity of composition and structure, researchers have speculated on the anabolic pathways of EPSs and the genes involved in the synthesis process. Studies to increase the yield of polysaccharides are limited because the synthesis pathways and anabolic regulation mechanisms of Cordyceps exopolysaccharide remain unknown. This review summarises the current researches in the yield of Cordyceps polysaccharides. A mechanism for the biosynthesis of Cordyceps polysaccharides was proposed by referring to the polysaccharide synthesis in other species. Furthermore, we also discuss the future perspective and ongoing challenges of EPS in uses of health foods and pharmaceutics.