Isolation, structure identification and anti-inflammatory activity of a polysaccharide from Phragmites rhizoma

Caragana sinica (Buc'hoz) Rehd. (jin ji er) polysaccharide regulates the immune function and intestinal microbiota of cyclophosphamide (CTX) induced immunosuppressed mice

ETHNOPHARMACOLOGICAL RELEVANCE

Caragana sinica (Buc'hoz) Rehd. is a plant widely grown in Yunnan, China, for both medicinal and edible purposes. The "National Compilation of Chinese Herbal Medicine" describes its nature as "slightly temperate and sweet". Caragana sinica is usually medicated with whole herbs, the main function is to replenish the kidneys and stop bleeding. Caragana sinica was used in folk medicine in Chuxiong, Yunnan, to treat deficiency colds, fatigue, fever, cough, hypertension, and other diseases.

AIM OF THE STUDY

This article investigates the structural characteristics of Caragana sinica polysaccharide (CSP) and explores its immune-regulatory activity and molecular biological mechanisms in cyclophosphamide-induced immunosuppressed mice, as well as its effects on intestinal bacteria.

METHODS

With the water-extraction and alcohol-precipitation method, Caragana sinica polysaccharide were extracted, obtaining CSP by purification. A variety of methods and techniques have been used to analyze the chemical properties and structural characteristics of CSP. Immunosuppressive mice model was established through intraperitoneal injection of cyclophosphamide (CTX) to study the immune-regulatory effects and mechanisms of CSP.

RESULTS

The data indicated that CSP is a neutral heteropolysaccharide mainly composed of arabinose and galactose. This article uses immunosuppressive mice induced by cyclophosphamide (CTX) as the model. The results showed that CSP can promote the immune function of CTX treated immunosuppressed mice and regulate the diversity and composition of intestinal microbiota. CSP can increase macrophage phagocytosis, NK cell killing activity, and lymphocyte proliferation activity. It can also repair the index and morphological damage of the thymus and spleen. And by binding to the TLR4 receptor, MyD88 was activated and interacted with TRAF6 to promote the transfer of NF-κB into the nucleus. Thereby promoting cytokine release and increasing the production of IL-1β, IL-6, IL-10, TNF-α, IgA, and IgG in the serum. CSP also effectively alleviated the liver damage caused by CTX through antioxidant activity. Furthermore, CSP can dramatically affect the intestinal microbiota and the body's immunity by boosting the relative presence of Bacteroides and Verrucamicrobiota.

CONCLUSIONS

Research results indicated that CSP can regulate the immune function of mice, providing a basis for developing CSP as a potential immune modulator and functional food.

Correlations between the structure and anti-diabetic activity of novel polysaccharides from raw and "Nine Steaming Nine Sun-Drying" Polygonti rhizome

"Nine Steaming Nine Sun-Drying" Polygonti rhizome has been used as valuable tonic health-care products for thousands of years. This research aimed to determine the correlations between the structure and anti-diabetic activities of three novel polysaccharides isolated from the raw and "Nine Steaming Nine Sun-Drying" Polygonti rhizome, with PRP-R from the raw ones and PRP-9Z and PRP-9A from the steamed ones. Structures of the isolated polysaccharides were determined by IR and NMR spectra, as well as monosaccharide composition and methylation analysis. In vitro assays indicated that PRP-9Z could improve the glucose consumptions more effectively than PRP-R and PRP-9A via Akt/GSK3β insulin signal pathway by western blotting analysis. In vivo assays indicated PRP-9Z could improve the glucose tolerance in the BKS-db mice. Histopathological assay demonstrated that PRP-9Z effectively reduced the damage of the kidney and liver. The above results indicated that PRP-9Z from "Nine Steaming Nine Sun-Drying" Polygonti rhizome showed significant anti-diabetic properties, which indicated that PRP-9Z with higher content of →1)-β-Frup-(2→ was more active than PRP-R with higher →1,6)-β-Fruf-(2→ and PRP-9A with higher →4)-β-Galp(1→.

Degradation Product of Sea Cucumber Polysaccharide by Dielectric Barrier Discharge Enhanced the Migration of Macrophage In Vitro

This study investigated the effect of dielectric barrier discharge (DBD) on sea cucumber polysaccharide (SP-2) and evaluated its anti-inflammatory properties. The SP-2 was depolymerized by applying an input voltage of 60~90 V for 3~9 min. The features of the products were examined using high-performance gel permeation chromatography, HPLC-PAD-MS, and the Fourier transform infrared (FTIR) spectrum. The anti-inflammatory properties of the product were investigated by measuring nitric oxide (NO) release, ROS accumulation, and cell migration using RAW264.7 cells (LPS-induced or not-induced). The results showed SP-2 depolymerized into homogeneous and controllable-size oligosaccharide products. The depolymerized ratio can reach 80%. The results of the measurement of reducing sugars indicate that SP-2 was cleaved from within the sugar chain. The SP-2 was deduced to have a monosaccharide sequence of GlcN-Man-Man-Man-Man-Man based on the digested fragment information. The depolymerization product restrained the release of NO and the accumulation of ROS. By testing the RAW264.7 cell scratch assay, it was found that it enhances the migration of immune cells. DBD degradation of SP-2 leads to homogeneous and controllable-size oligosaccharide products, and this technique can be used for polysaccharide structure analysis. The depolymerized product of SP-2 has an anti-inflammatory capability in vitro.

Xuanfei Baidu decoction in the treatment of coronavirus disease 2019 (COVID-19): Efficacy and potential mechanisms

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has spread worldwide and become a major global public health concern. Although novel investigational COVID-19 antiviral candidates such as the Pfizer agent PAXLOVID™, molnupiravir, baricitinib, remdesivir, and favipiravir are currently used to treat patients with COVID-19, there is still a critical need for the development of additional treatments, as the recommended therapeutic options are frequently ineffective against SARS-CoV-2. The efficacy and safety of vaccines remain uncertain, particularly with the emergence of several variants. All 10 versions of the National Health Commission's diagnosis and treatment guidelines for COVID-19 recommend using traditional Chinese medicine. Xuanfei Baidu Decoction (XFBD) is one of the "three Chinese medicines and three Chinese prescriptions" recommended for COVID-19. This review summarizes the clinical evidence and potential mechanisms of action of XFBD for COVID-19 treatment. With XFBD, patients with COVID-19 experience improved clinical symptoms, shorter hospital stay, prevention of the progression of their symptoms from mild to moderate and severe symptoms, and reduced mortality in critically ill patients. The mechanisms of action may be associated with its direct antiviral, anti-inflammatory, immunomodulatory, antioxidative, and antimicrobial properties. High-quality clinical and experimental studies are needed to further explore the clinical efficacy and underlying mechanisms of XFBD in COVID-19 treatment.

Structural characterization and anti-inflammatory activity of a novel neutral polysaccharide isolated from Smilax glabra Roxb

Crude polysaccharides isolated from Smilax glabra were screened for anti-inflammatory activity using mice ear swelling animal experiments, during which the neutral polysaccharide S1 was identified. The structural characteristics and anti-inflammatory effects of the anti-inflammatory S1 polysaccharide were then investigated. The results showed that S1 was mainly composed of rhamnose, arabinose, galactose, glucose, xylose, and mannose. The structure of the main chain consisted of →6)-α-Galp-(1 → 6)-β-Galp-(1 → 4)-α-Xylp-(1 → 6)-β-Galp-(1→, with branched chains comprising α-Araf-(1 → 4)-α → Manp-(1 → and β-Rhap-(1 → 4)-α-Glcp-(1 → units. Furthermore, S1 did not have a triple helix conformation. S1 could inhibit NO secretion, reduce the levels of pro-inflammatory factors (IL-6 and TNF-α), and significantly reduce LPS-stimulated inflammatory damage in RAW 264.7 cells by inhibiting activation of the NF-κB (p65) pathway. These results shed light on the possibility of S1 to be developed as a novel anti-inflammatory drug for therapeutic purposes.

Structural characteristics, antioxidant and hypoglycemic activities of polysaccharides from Mori Fructus based on different extraction methods

The mulberry (Mori Fructus), which is rich in many nutrients needed by the human body, serves as both food and medicine. Polysaccharides, which are considered to be important pharmacological components of mulberry, have received a lot of study for their structure and biological activity. In this study, six mulberry fruit polysaccharides (MFPs) were extracted by different extraction methods, and their physicochemical structures, antioxidant, and hypoglycemic biological activities were investigated and compared. According to the findings, MFP-III exhibited the best α-glucosidase and α-amylase inhibition, whereas MFP-IV had the strongest scavenging activity against DPPH and ABTS. Scanner electron microscopy (SEM) and high-performance liquid chromatography (HPLC) analysis showed that the apparent morphology and monosaccharide content of MFP were significantly impacted by the different extraction techniques. The results of experiments using Congo red, Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TG), and the Congo red experiment showed that the MFP functional groups, glycosidic bonds, triple helix structure, and thermal stability were not significantly different between the extraction methods. According to the aforementioned research, various extraction methods had different effects on the chemical composition and biological activity of mulberry polysaccharides. This information can provide a scientific basis for selecting suitable extraction methods to obtain mulberry polysaccharides with ideal biological activity.

A polysaccharide/chitin hydrogel wound dressing from a Periplanattica americana residue: coagulation, antioxidant activity, and wound healing properties

Pharmaceuticals derived from the raw materials of Periplanattica americana have been applied for wound healing, liver disease treatment, and antitumor therapy. However, the resulting residues of P. americana have not been well exploited. We found that P. americana residues comprised high amounts of chitin (PC) and polysaccharides (PAP) exhibit good biological activity. Compared to shrimp-derived chitin, PC has a smaller molecular weight (Mv), lower crystallinity, and looser molecular structure, demonstrating stronger antioxidant activity and degradability. After adding the PAP, the PC solution rapidly lost fluidity and formed a hydrogel (P/PCGEL) that had antioxidation, biodegradability, and injectability properties and exhibited rapid coagulation, good water absorption and retention, and a low hemolysis rate (HR). In vivo studies reported that the P/PCGEL reduced edema during burns, accelerated collagen synthesis and deposition, reduced reactive oxygen species (ROS) levels, and increased superoxide dismutase (SOD) levels, thereby reducing the inflammatory response, avoiding oxidative stress, and effectively promoting wound healing. Furthermore, the P/PCGEL demonstrated good biocompatibility, rapid biodegradation, and injectability, thereby reducing the risk of trauma and infection engendered by repeated wound opening and dressing changes. These properties also demonstrated the potential application for this hydrogel in preparing injectable hydrogel excipients. Hence, this study provided a hydrogel-formed wound dressing comprising pure natural ingredients and offering convenient administration, economic availability, and strong tissue repair ability.

Endophytic Fungi and Secondary Metabolites of Rehmannia Glutinosa Based on Traditional Chinese Medicine Fingerprints

Research on the active components of medicinal plants has always been the focus of research, and research on the active components of medicinal plant endophytic fungi and their secondary metabolites has also attracted widespread attention. Endophytic fungi of medicinal plants are widely distributed and are ubiquitous in various biological groups in nature. Rehmannia glutinosa contains a variety of active ingredients, which are regarded as the top grade of Chinese medicinal materials. It is of certain significance to study endophytic fungi and their metabolites of Rehmannia glutinosa. In this paper, endophytic fungi and their secondary metabolites of Rehmannia glutinosa were studied using fingerprint technology, which initially understands the diversity of endophytic fungi in Rehmannia glutinosa. In this paper, the roots and leaves of Rehmannia glutinosa were used as experimental materials. The fungi were cultured in the medium, the fungi were isolated and purified by the tissue block method, the fungal growth of Rehmannia glutinosa in different parts was determined, and the types of endophytic fungi were identified by microscopic identification and fingerprinting. The isolated strains were tested for biological activity using oryza oryzae spores, and highly active strains were screened. Fermentation products of endophytic fungi were separated and purified by chromatography, and the structure of the compounds was identified by nuclear magnetic resonance spectroscopy. Through the above studies, the population structure of endophytic fungi of Rehmannia glutinosa was determined, 3 highly active strains were found, and the structures of 7 endophytic fungi metabolites were identified, of which 3 were newly discovered compounds.

Phragmites rhizoma polysaccharide-based nanocarriers for synergistic treatment of ulcerative colitis

The purpose of this study was to construct Phragmites rhizoma polysaccharide-based nano-drug delivery systems (PRP2-SeNPs-H/Aza-Lips) for synergistically alleviating ulcerative colitis and to investigate the important roles of Phragmites rhizoma polysaccharide-based nanocarriers in PRP2-SeNPs-H/Aza-Lips. Phragmites rhizoma polysaccharide (PRP2) was isolated and used for the preparation of Phragmites rhizoma polysaccharide selenium nanoparticles with low selenium content (PRP2-SeNPs-L) and high selenium content (PRP2-SeNPs-H). Based on the electrostatic attraction between PRP2-SeNPs-H and azathioprine liposomes (Aza-Lips), PRP2-SeNPs-H/Aza-Lips were constructed for precise delivery of the model drug azathioprine (Aza) to colon lesions. Results showed that PRP2 significantly alleviated the clinical symptoms and colon tissue damage and down-regulated the levels of inflammatory factors in serum and colon, demonstrating beneficial effects on mice with ulcerative colitis. PRP2-SeNPs-L had better relieving effects on ulcerative colitis. Phragmites rhizoma polysaccharide-based nanocarriers may protect azathioprine liposomes against gastrointestinal digestion, enhance the therapeutic effects on ulcerative colitis, and significantly reduce liver damage from azathioprine, which helps to improve the efficacy and toxicity of clinical drugs.

Comparative Characterization and Immunomodulatory Activities of Polysaccharides Extracted from the Radix of Platycodon grandiflorum with Different Extraction Methods

Platycodon grandiflorum is an edible and medicinal plant, and polysaccharides are one of its important components. To further improve the utilization rate of P. grandiflorum, we investigated the effects of four different extraction methods, including hot water, ultrasonic-assisted, acid-assisted, and alkali-assisted extractions, on the polysaccharides, which were named PG-H, PG-U, PG-C, and PG-A. The findings indicated that the extraction method had a significant impact on the yield, characteristics, and immunoregulatory activity. We observed that the yields decreased in the following order: PG-H, PG-U, PG-C, and PG-A. Galacturonic acid, glucose, galactose, and arabinose were the most prevalent monosaccharides in the four PGs. However, their proportions varied. In addition, the difference between the content of glucose and galacturonic acid was more significant. PG-U had the highest glucose content, whereas PG-C had the lowest. Galacturonic acid content was highest in PG-A, while the lowest in PG-U. The molecular weight decreased in the order of PG-U, PG-H, PG-C, and PG-A; the particle size was in the order of PG-U, PG-A, PG-H, and PG-C. Moreover, the extraction method had a great impact on immunoregulatory activity. The ability to stimulate the immune function of macrophages was as follows: PG-A > PG-C > PG-U > PG-H. The results indicated that PGs, with lower molecular weights and higher GalA content, exhibited better immune-stimulating activity. And more important the AAE method was a good way to extract polysaccharides from Platycodon grandiflorum for use as a functional product and immunological adjuvant.

Isolation, Structural Analysis and Anti-Inflammatory Activity of a Polysaccharide from Ilex cornuta Fruits

In the present study, a polysaccharide from Ilex cornuta fruits (LCFP-3) was obtained by hot water extraction, Diethyaminoethyl cellulose-52 (DEAE-52) chromatography column and Sephadex G-100 gel column purification. Its structural characteristics were further explored using high performance anion exchange chromatography (HPAEC), gas chromatography and mass spectrometry (GC/MS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Monosaccharide composition analysis revealed LCFP-3 contained mainly Galactose (31.92 %), Arabinose (25.87 %) and Galacturonic acid (23.35 %) while small percentage of Rhamnose, Glucose, Mannose and Xylose. Chemical composition analysis showed that the total sugar content of LCFP-3 was 90.31 % and the protein content was 0.246 %. Gel permeation chromatography (GPC) analysis showed that its average molecular weight was 41.199 kDa. Structural analysis showed that LCFP-3 may be composed of residues, T-α-Arap, T-α-Rhap, 1,3-α-Arap, 1,4-α-Arap, T-β-Galp, 1,4-α-GalpA(OMe), 1,4-β-Glcp, 1,3-β-Galp, 1,3,6-β-Manp, 1,6-β-Galp, 1,3,4-β-GalpA, 1,4,6-β-Manp, 1,3,6-β-Glcp, 1,2,3,4-α-Xylp. The anti-inflammatory activity of LCFP-3 was evaluated using lipopolysaccharide (LPS)-induced RAW246.7 macrophages. The results showed that 1-200 μg/mL LCFP-3 could dose-dependently protect against LPS-induced toxicity and 1 μg/mL LCFP-3 could significantly inhibit LPS-induced NO production. Therefore, LCFP-3 exerted an anti-inflammatory activity and has great potential as a functional ingredient.

Mycelium polysaccharides of Macrolepiota procera alleviate reproductive impairments induced by nonylphenol

Nonylphenol (NP) exposure has become a crucial inducement of male reproductive disorders in the world. Therefore, it is urgent to seek solutions to alleviate the toxicity of NP. This study was oriented toward studying the protective effects of Macrolepiota procera mycelium polysaccharides (MMP) on NP-induced reproductive impairments. After NP administration, declined sperm amounts and testis index, increased the deformity rate of sperms, aberrant hormone secretion and testicular pathological injury were observed, corporately leading to reproductive capacity attenuation. Importantly, MMP significantly reversed the foregoing changes in NP-treated mice. Notably, it has been observed that the MMP therapy remarkably improved oxidative stress, apoptosis, autophagy and inflammatory responses, and suppressed the Akt/mTOR signaling pathway in testicular tissues. These results manifested that MMP might be a promising treatment strategy for ameliorating the biotoxicity of NP.

The hypoglycemic and hypolipemic potentials of Moringa oleifera leaf polysaccharide and polysaccharide-flavonoid complex

In this study, Moringa oleifera leaf (MOL) flavonoids (MOLF) with strong α-glucosidase inhibitory activity and MOL polysaccharides (MOLP) with strong cholic acid-binding capacity were efficiently prepared by two-stage extraction method and mixed in a certain proportion for development of MOL highly-processed products with hypoglycemic and hypolipemic potentials. Quercetin-3-O-glucoside (6.86%) and kaempferol-3-O-glucoside (4.02%) were identified as the main components of MOLF. MOLP constructed by galactose, arabinose, rhamnose and galacturonic acid possessed the strongest effects on delaying glucose diffusion and dialysis, delaying starch digestion, binding bile acids and inhibiting cholesterol micelle solubility, being the best MOL highly-processed products for regulating carbohydrate and lipid digestion and absorption. MOLF and MOLP had synergistic effect on delaying glucose diffusion and dialysis, delaying starch digestion and binding bile acids, while MOLF impaired the inhibitory effect of MOLP on cholesterol micelle solubility. Compared with MOL primary-processed products including MOL powder and de-phenolic MOL powder, MOL highly-processed products including MOLP and MOLF-MOLP complex possessed stronger hypoglycemic/hypolipemic potentials.

Structural characterization of a polysaccharide from Trametes sanguinea Lloyd with immune-enhancing activity via activation of TLR4

A bioactive polysaccharide (TS2-2A) with a molecular weight of 15 kDa was isolated from Trametes sanguinea Lloyd, a medicinal food homologous fungus, by water extraction-alcohol precipitation and chromatographic separation. NMR analysis of polysaccharide and MS/MS analysis of its oligosaccharide indicated that TS2-2A featured a novel straight chain with a backbone of 1,3-α-d-glucopyranose and 1,4-β-d-glucopyranose at a molar ratio of 1:4. Moreover, TS2-2A, recognized by Toll-like receptor 4 (TLR4), stimulated RAW 264.7 macrophages to release related cytokines and contributed to immune-enhancing effects. Briefly, with remarkable immune-enhancing activity and noncytotoxicity, TS2-2A was proposed to be a potential immune enhancer for supplementing drugs or functional foods.

Digestive Characteristics of Hericium erinaceus Polysaccharides and Their Positive Effects on Fecal Microbiota of Male and Female Volunteers During in vitro Fermentation

Hericium erinaceus polysaccharides (HEPs) have attracted widespread attention in regulating gut microbiota (GM). To investigate digestibility and fermentation of HEPs and their effects on GM composition, three polysaccharide fractions, namely, HEP-30, HEP-50, and HEP-70, were fractionally precipitated with 30%, 50%, and 70% ethanol concentrations (v/v) from hot water-soluble extracts of Hericium erinaceus, respectively. Three kinds of prepared HEPs were structurally characterized and simulated gastrointestinal digestion, and their effects on human fecal microbiota fermentations of male and female and short-chain fatty acid (SCFA) production in vitro were clarified. Under digestive conditions simulating saliva, stomach, and small intestine, HEPs were not significantly influenced and safely reached the distal intestine. After 24 h of in vitro fermentation, the content of SCFAs was significantly enhanced (p < 0.05), and the retention rates of total and reducing sugars and pH value were significantly decreased (p < 0.05). Thus, HEPs could be utilized by GM, especially HEP-50, and enhanced the relative abundance of SCFA-producing bacteria, e.g., Bifidobacterium, Faecalibacterium, Blautia, Butyricicoccus, and Lactobacillus. Furthermore, HEPs reduced the relative abundances of opportunistic pathogenic bacteria, e.g., Escherichia-Shigella, Klebsiella, and Enterobacter. This study suggests that gradual ethanol precipitation is available for the preparation of polysaccharides from Hericium erinaceus, and the extracted polysaccharide could be developed as functional foods with great development value.

Traditional Uses, Phytochemistry, Pharmacology and Toxicology of Rhizoma phragmitis: A Narrative Review

Rhizoma phragmitis is a common Chinese herbal medicine whose effects are defined as ‘clearing heat and fire, promoting fluid production to quench thirst, eliminating irritability, stopping vomiting, and disinhibiting urine’. During the Novel Coronavirus epidemic in 2020, the Weijing Decoction and Wuye Lugen Decoction, with Rhizoma phragmitis as the main herbal component, were included in The Pneumonia Treatment Protocol for Novel Coronavirus Infection (Trial Version 5) due to remarkable antiviral effects. Modern pharmacological studies have shown that Rhizoma phragmitis has antiviral, antioxidative, anti-inflammatory, analgesic, and hypoglycemic functions, lowers blood lipids and protects the liver and kidney. This review aims to provide a systematic summary of the botany, traditional applications, phytochemistry, pharmacology and toxicology of Rhizoma phragmitis.

Ameliorative Effects of Humulus japonicus Extract and Polysaccharide-Rich Extract of Phragmites rhizoma in Rats with Gastrointestinal Dysfunctions Induced by Water Avoidance Stress

Chronic stress can cause the gastrointestinal disorders characterized by an altered bowel movement and abdominal pain. Studies have shown that Humulus japonicus extract (HJE) has anti-inflammatory and antidiarrheal effects, and Phragmites rhizoma extract (PEP) has antioxidative and antistress effects. The present study aimed to investigate the possible effects of HJE and PEP in rat models with stress-induced gastrointestinal dysfunctions. The rats were exposed to water avoidance stress (WAS, 1 h/day) for 10 days to induce gastrointestinal disorders. We found that WAS significantly increased fecal pellet output during 1 h stress, gastric emptying, colonic contractility, and permeability compared to the normal rats. Pretreatment with HJE and PEP (0.25 and 0.5 mL/kg, both administered separately) improved the increased gastric emptying and colonic contractility induced by electrical field stimulation, acetylcholine, and serotonin and also alleviated the increased colonic permeability. HJE and PEP also increased the claudin-1 and occludin expressions, reduced by WAS. WAS increased the concentration of TNF-α and TBARS and reduced FRAP. HJE and PEP recovered these effects. HJE and PEP improved the gastrointestinal disorders induced by WAS by upregulating the tight junction protein, possibly acting on cholinergic and serotonergic receptors to abolish the colonic hypercontractility and hyperpermeability and degradation of inflammatory cytokines via an antioxidant effect.

Structural characterisation and bioactivity of polysaccharides isolated from fermented Dendrobium officinale

BACKGROUND

A polysaccharide was purified in this study, which was acquired from the fermentation broth of Dendrobium officinale Kimura et Migo. We aimed to investigate the structural features and bioactivity of this polysaccharide.

RESULTS

The polysaccharide was purified and the main polysaccharide fraction (i.e., DOP-1) was obtained. High-performance gel permeation chromatography (HPGPC) revealed that the molecular weight of DOP-1 was 447.48 kDa. Galactose, glucose and mannose were found to be present in DOP-1 via monosaccharide composition analysis, at a ratio of 1:1.79:6.71. Methylation and nuclear magnetic resonance spectroscopic analysis indicated that the backbone of DOP-1 was →4)-α-d-Glcp-(1 → 4)-α-d-Manp-(1 → 4)-α-d-Manp-(1 → 4,6)-α-d-Manp-(1→, and its repeating units were also preliminarily established. In vitro tests proved that DOP-1 not only protects RAW264.7 macrophages from the cytotoxic effect induced by lipopolysaccharide (LPS), but also inhibits cytokines (i.e., interleukin-6 and tumour necrosis factor-α) induced by LPS. DOP-1 demonstrated good scavenging activity in vitro toward 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radicals, as well as good metal chelating activity. Therefore, DOP-1 has potential antioxidant applications.

CONCLUSION

The structural characteristics of DOP-1 support its favourable biological activities and lay a strong foundation for further exploration of its structure-activity relationships and activity development, providing experimental data for the development and utilisation of fermentation broth of D. officinale. © 2021 Society of Chemical Industry.

Multifunctional Self-Healing Dual Network Hydrogels Constructed via Host-Guest Interaction and Dynamic Covalent Bond as Wearable Strain Sensors for Monitoring Human and Organ Motions

Hydrogel-based flexible strain sensors have shown great potential in body movement tracking, early disease diagnosis, noninvasive treatment, electronic skins, and soft robotics. The good self-healing, biocompatible, sensitive and stretchable properties are the focus of hydrogel-based flexible strain sensors. Dual network (DN) hydrogels are hopeful to fabricate self-healing hydrogels with the above properties. Here, multifunctional DN hydrogels are prepared via a combination of host-guest interaction of β-cyclodextrin and ferrocene with dynamic borate ester bonds of poly(vinyl alcohol) and borax. Carbon nanotubes are used to endow the DN hydrogels with good conductivity. The obtained DN composite hydrogels possess good biocompatibility, stretchability (436%), fracture strength (41.0 KPa), self-healing property (healing efficiency of 95%), and high tensile strain sensitivity (gauge factor of 5.9). The DN composite hydrogels are used as flexible strain sensors to detect different human motions. After cutting, the healed hydrogels also can monitor human motions and have good stability. In addition, the hydrogel sensors may track the respiratory movement of a pig lung in vitro. This work exhibits new ideas and approaches to develop multifunctional self-healing hydrogels for constructing flexible strain sensors.

A Multifunctional, Self-Healing, Self-Adhesive, and Conductive Sodium Alginate/Poly(vinyl alcohol) Composite Hydrogel as a Flexible Strain Sensor

Hydrogel-based wearable devices have attracted tremendous interest due to their potential applications in electronic skins, soft robotics, and sensors. However, it is still a challenge for hydrogel-based wearable devices to be integrated with high conductivity, a self-healing ability, remoldability, self-adhesiveness, good mechanical strength and high stretchability, good biocompatibility, and stimulus-responsiveness. Herein, multifunctional conductive composite hydrogels were fabricated by a simple one-pot method based on poly(vinyl alcohol) (PVA), sodium alginate (SA), and tannic acid (TA) using borax as a cross-linker. The composite hydrogel network was built by borate ester bonds and hydrogen bonds. The obtained hydrogel exhibited pH- and sugar-responsiveness, high stretchability (780% strain), and fast self-healing performance with healing efficiency (HE) as high as 93.56% without any external stimulus. Additionally, the hydrogel displayed considerable conductive behavior and stable changes of resistance with high sensitivity (gauge factor (GF) = 15.98 at a strain of 780%). The hydrogel was further applied as a strain sensor for monitoring large and tiny human motions with durable stability. Significantly, the healed hydrogel also showed good sensing behavior. This work broadens the avenue for the design and preparation of biocompatible polymer-based hydrogels to promote the application of hydrogel sensors with comfortable wearing feel and high sensitivity.