Water-soluble polysaccharides from Pleurotus eryngii fruiting bodies, their activity and affinity for Toll-like receptor 2 and dectin-1

Chemical structure characterization of polysaccharides using diffusion ordered NMR spectroscopy (DOSY)

The potential of DOSY NMR spectroscopy to distinguish the linkage pattern of chemically related polysaccharides was evaluated using β-glucans isolated from yeast (Saccharomyces cerevisiae) and mushroom (Pleurotus eryngii). Laminarin from Laminaria digitata was included for chemical shift comparison. Characterization through methylation and 1D/2D NMR analysis showed that all the samples were constituted by →3)-Glcp-(1→; →3,6)-Glcp-(1→; Glcp-(1→ and →6)-Glcp-(1→ linkages. The results obtained allowed the identification of the well-known chemical structure of laminarin. Moreover, DOSY demonstrated that the units →3)-Glcp-(1→ and →6)-Glcp-(1→ from yeast β-glucans, presented the same diffusion time. For the mushrooms β-glucans, the diffusion time of these units were different, confirming that they belong to distinct polysaccharides. The yeast and the mushroom polysaccharide samples presented the same NMR correlations, but after DOSY analysis, different structures could be proposed. Therefore, DOSY NMR spectroscopy could be a tool for the identification of different linkage patterns of polysaccharides belonging to the same group and may be a useful contribution to the chemical structure and biological activity correlation studies of such structures.

The effect of β-Glucan induced intestinal trained immunity against Trichinella spiralis infection

Parasitic helminth Trichinella spiralis (Ts) induce mixed Th1/Th2 response with predominant type 2 immune responses, with protective immunity mediated by interleukin (IL)-4, IL-5, and IL-13. β-Glucan (BG) has been shown to have the ability to induce trained immunity, confers non-specific protection from secondary infections. However, whether BG-induced trained immunity played a role in protective type 2 immunity against Ts infection is unclear. In this study, BG was administered five days before Ts infection to induce trained immunity. Our findings demonstrate that BG pretreatment effectively reduced the number of T. spiralis adults and muscle larvae, whereas inhibition of trained immunity abolished the effect of BG. Additionally, we observed a significant increase in goblet cells and mucus production as evidenced by Alcian blue periodic acid-Schiff staining. Furthermore, quantitative real-time PCR analysis revealed a significant upregulation of IL-4, IL-5, and IL-13 expression in response to BG. Conversely, the inhibitor of trained immunity reversed these effects, suggesting that BG-induced trained immunity confers strong protection against Ts infection. In conclusion, these findings suggest that BG-induced trained immunity may play a role in protection against infections caused by other helminths.

Immunostimulatory activity of sea buckthorn polysaccharides via TLR2/4-mediated MAPK and NF-κB signaling pathways in vitro and in vivo

SP0.1-1, derived from Sea buckthorn (Hippophae rhamnoides L.), has been discovered to exhibit unique antioxidant activity. In this study, we investigated the immunomodulatory activity and mechanisms of SP0.1-1 on macrophage RAW 264.7 cells in vitro and immunosuppressive mice induced by cyclophosphamide in vivo. The results indicated SP0.1-1 strengthened the immune functions via promoting the proliferation of RAW264.7 cells and phagocytic activity, along with stimulating the release of NO, ROS and cytokines including TNF-α, IL-6, IL-1β and IFN-γ. Western blot and molecular docking analysis demonstrated that SP0.1-1 attached to the prime receptors TLR2 and TLR4 in RAW264.7 cells, and triggered the activation of MyD88-mediated MAPK and NF-κB signaling pathways, thereby exerting the immune response in RAW264.7 cells. However, the intervention of specific inhibitors against TLR2, TLR4, JNK, ERK, p38 and NF-κB blocked the TLR-mediated MAPK and NF-κB signaling pathways and downregulated the levels of NO and the aforementioned cytokines, thus suppressing the activation of macrophages. Therefore, it can be speculated that SP0.1-1 activated the macrophages principally via the TLR2/4-MyD88-mediated MAPK and NF-κB signaling pathways. Additionally, SP0.1-1 could protect against the cyclophosphamide-induced immunosuppression in mice, manifested by the improvement of body weight, immune organ indices, phagocytic index, and the relievement of spleen damage, along with the enhancement of cytokines TNF-α, IL-6, IFN-γ and immunoglobulin IgG and IgM. These findings will shed light on the molecular mechanism of SP0.1-1 on the immunoregulatory effect, and lay the foundation for exploiting a potential immunostimulatory agent of SP0.1-1.

Experimental Models in Unraveling the Biological Mechanisms of Mushroom-Derived Bioactives against Aging- and Lifestyle-Related Diseases: A Review

Mushrooms have garnered considerable interest among researchers due to their immense nutritional and therapeutic properties. The presence of biologically active primary and secondary metabolites, which includes several micronutrients, including vitamins, essential minerals, and other dietary fibers, makes them an excellent functional food. Moreover, the dietary inclusion of mushrooms has been reported to reduce the incidence of aging- and lifestyle-related diseases, such as cancer, obesity, and stroke, as well as to provide overall health benefits by promoting immunomodulation, antioxidant activity, and enhancement of gut microbial flora. The multifunctional activities of several mushroom extracts have been evaluated by both in vitro and in vivo studies using cell lines along with invertebrate and vertebrate model systems to address human diseases and disorders at functional and molecular levels. Although each model has its own strengths as well as lacunas, various studies have generated a plethora of data regarding the regulating players that are modulated in order to provide various protective activities; hence, this review intends to compile and provide an overview of the plausible mechanism of action of mushroom-derived bioactives, which will be helpful in future medicinal explorations.

A systematic review on polysaccharides from Morinda officinalis How: Advances in the preparation, structural characterization and pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

Morinda officinalis How is called "Ba-Ji-Tian" in Traditional Chinese Medicine (TCM), which belongs to the genus Rubiaceae and is widely used for medicinal purposes in China and other eastern Asian countries. Morinda officinalis How polysaccharides (MOPs) are one of the key bioactive components, and have a variety of biological activities, such as antioxidation, antifatigue, enhanced immunity, antiosteoporosis, ect.

AIM OF THE REVIEW

This review is aimed at providing comprehensive information of the latest preparation technologies, structural characterization, and pharmacological effects of MOPs. A more in-depth research on the structure and clinical pharmacology of the MOPs was explored. It could lay a foundation for further investigate the pharmacological activities and guide the safe clinical practice of MOPs.

MATERIALS AND METHODS

The Web of Science, PubMed, Scifinder, Google Scholar, CNKI, Wanfang database, and other online database are used to search and collect the literature on extraction and separation methods, structural characterization, and pharmacological activities of MOPs publisher from 2004 to 2023. The key words are "Morinda officinalis polysaccharides", "extraction", "isolation", "purification" and "pharmacological effects".

RESULTS

Morinda officinalis has been widely used in tonifying the kidney yang since ancient times, and is famous for one of the "Four Southern Medicines" in China for the treatment of depression, osteoporosis, rheumatoid arthritis, infertility, fatigue and Alzheimer's disease. The active ingredients of Morinda officinalis that have been researched on the treatment of depression and osteoporosis are mostly polysaccharides and oligosaccharides. The content of polysaccharides varies with different methods of extraction, separation and purification. MOPs have a wide range of pharmacological effects, including antioxidant, antifatigue, immunomodulatory, antiosteoporosis, and regulation of spermatogenesis activities. These pharmacological properties lay a foundation for the treatment of oxidative stress, osteoporosis, spermatogenic dysfunction, immunodeficiency, inflammation and other diseases with MOPs.

CONCLUSIONS

At present, MOPs have been applied in the treatment of skeletal muscle atrophy, varicocele, osteoporosis, because of its effects of enhancing immunity, improving reproduction and antioxidant. However, the structure-activity relationship of these effects are still not clear. The more deeply study could be conducted on the MOPs in the future. The toxicology and clinical pharmacology, as well as mechanism of action of MOPs were also needed to deeply studied and clarified. This paper could lay the foundation for the application and safety of MOPs in multifunctional foods and drugs.

Structural characterization, chain conformation and immunomodulatory activity of a heteropolysaccharide from Inonotus hispidus

A new polysaccharide (IHP-1aa) was isolated from the fruiting body of Inonotus hispidus by hot water extraction, ethanol precipitation and column chromatography. The molecular weight of IHP-1aa was 26.9 kDa. Structural analysis showed that IHP-1aa consisted of glucose (Glc), galactose (Gal), fucose (Fuc), mannose (Man) and contained a certain amount of 3-O-methylgalactose (3-O-Me-Gal). The structure was mainly composed of →6)-α/β-D-Glcp-(1→, →6)-α-D-Galp-(1→, →6)-(3-O-Me)-α-D-Galp-(1→, →6)-α-D-Manp-(1 → and →2, 6)-α-D-Galp-(1 → as the main chain. Branched at O-2 with single β-L-Fucp-(1 → 6)-α-D-Galp-(1 → 6)-α-D-Glcp-(1 → as major the side chain. The results of SEM, XRD and AFM combined with Congo red indicated that IHP-1aa may be amorphous granular chain conformation. In addition, IHP-1aa stimulated macrophage function and improved phagocytic ability of RAW264.7, as well as promoted the secretion of NO, TNF-α and IL-6. IHP-1aa, a 3-O-methylgalactose-containing heteropolysaccharide, was isolated for the first time from the I. hispidus, which may be used as a potential immunomodulator in functional foods.

Structural characterization and anti-oxidative activity for a glycopeptide from Ganoderma lucidum fruiting body

A water-soluble glycopeptide (named GL-PWQ3) with a molecular weight (Mw) of 2.40 × 104 g/mol was isolated from Ganoderma lucidum fruiting body by hot water extraction, membrane ultrafiltration, and gel column chromatography, which mainly consisted of glucose and galactose. Based on the methylation, FT-IR, 1D, and 2D NMR analysis, the polysaccharide portion of GL-PWQ3 was identified as a glucogalactan, which was comprised of unsubstituted (1,6-α-Galp, 1,6-β-Glcp, 1,4-β-Glcp) and monosubstituted (1,2,6-α-Galp and 1,3,6-β-Glcp) in the backbone and possible branches that at the O-3 position of 1,3-Glcp and T-Glcp, and the O-2 position of T-Fucp, T-Manp or T-Glcp. The chain conformational study by SEC-MALLS-RI and AFM revealed that GL-PWQ3 was identified as a highly branched polysaccharide with a polydispersity index of 1.25, and might have compact sphere structures caused by stacked multiple chains. Moreover, the GL-PWQ3 shows strong anti-oxidative activity in NRK-52E cells. This study provides a theoretical basis for further elucidating the structure-functionality relationships of GL-PWQ3 and its potential application as a natural antioxidant in pharmacotherapy as well as functional food additives.

The amelioration of a purified Pleurotus abieticola polysaccharide on atherosclerosis in ApoE-/- mice

In this study, a polysaccharide known as PAPS2 was eluted from Pleurotus abieticola fruiting bodies using 0.1 M NaCl solutions. PAPS2 has a Mw of 19.64 kDa and its backbone is mainly composed of →6)-α-D-Galp-(1→, →6)-β-D-Glcp-(1→ and →2,6)-α-D-Galp-(1→ residues, and its branches mainly end with β-D-Manp-(1→, which is attached at C2 of →2,6)-α-D-Galp-(1→. PAPS2 elicited several effects in high-fat diet (HFD)-fed ApoE-/- mice. It significantly reduced the body weight, liver index, and serum levels of total cholesterol (TC) and triglycerides (TGs), and it alleviated lipid accumulation in the aorta. Intestinal microflora analysis showed that PAPS2 suppressed the abundances of Adlercreutzia, Turicibacter, and Helicobacter and enriched that of Roseburia. It also influenced lipid metabolism, suggesting that it reduced the levels of TGs, lysophosphatidylcholine (LPC), phosphatidylcholine (PC), and ceramide (Cer). Moreover, it suppressed oxidative response by increasing nuclear factor erythroid 2 (Nrf2)-related factor expression and activating the antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) to reduce the level of reactive oxygen species (ROS). Meanwhile, it showed anti-inflammatory effects partially related to the inhibition of toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) signaling induced by lipopolysaccharide (LPS) in RAW 264.7 cells, as well as in the aorta of HFD-fed ApoE-/- mice. This study provides experimental evidence of the auxiliary applicability of PAPS2 in atherosclerosis treatment.

Investigation of the structural and immunomodulatory properties of alkali-soluble β-glucans from Pleurotus eryngii fruiting bodies

Fungal β-glucans have received a lot of interest due to their proinflammatory activity towards cells of the innate immune system. Although commonly described as (1➔3)-β-glucans with varying degree of (1➔6)-branching, the fungal β-glucans constitute a diverse polysaccharide class. In this study, the alkali-soluble β-glucans from the edible mushroom Pleurotus eryngii were extracted and characterized by GC, GC-MS and 2D NMR analyses. The extracts contain several structurally different polysaccharides, including a (1➔3)-β-d-glucan with single glucose units attached at O-6, and a (1➔6)-β-d-glucan, possibly branched at O-3. The immunomodulatory activities of the P. eryngii extracts were assessed by investigating their ability to bind to the receptor dectin-1, and their ability to induce production of the proinflammatory cytokines TNF-α, IL-6 and IL-1β in LPS-differentiated THP-1 cells. Although the samples were able to bind to the dectin-1a receptor, they did not induce production of significant levels of cytokines in the THP-1 cells. Positive controls of yeast-derived (1➔3)-β-d-glucans with branches at O-6 induced cytokine production in the cells. Thus, it appears that the P. eryngii β-glucans are unable to induce production of proinflammatory cytokines in LPS-differentiated THP-1 cells, despite being able to activate the human dectin-1a receptor.

Nature's soothing solution: Harnessing the potential of food-derived polysaccharides to control inflammation

Reducing inflammation by diet is a major goal for prevention or lowering symptoms of a variety of diseases, such as auto-immune reactions and cancers. Natural polysaccharides are increasingly gaining attention due to their potential immunomodulating capacity. Structures of those molecules are highly important for their effects on the innate immune system, cytokine production and secretion, and enzymes in immune cells. Such polysaccharides include β-glucans, pectins, fucoidans, and fructans. To better understand the potential of these immunomodulatory molecules, it is crucial to enhance dedicated research in the area. A bibliometric analysis was performed to set a starting observation point. Major pillars of inflammation, such as pattern recognition receptors (PRRs), enzymatic production of inflammatory molecules, and involvement in specific pathways such as Nuclear-factor kappa-B (NF-kB), involved in cell transcription, survival, and cytokine production, and mitogen-activated protein kinase (MAPK), a regulator of genetic expression, mitosis, and cell differentiation. Therefore, the outcomes from polysaccharide applications in those scenarios are discussed.

Post-COVID-19 syndrome management: Utilizing the potential of dietary polysaccharides

The COVID-19 pandemic has caused significant global impact, resulting in long-term health effects for many individuals. As more patients recover, there is a growing need to identify effective management strategies for ongoing health concerns, such as post-COVID-19 syndrome, characterized by persistent symptoms or complications beyond several weeks or months from the onset of symptoms. In this review, we explore the potential of dietary polysaccharides as a promising approach to managing post-COVID-19 syndrome. We summarize the immunomodulatory, antioxidant, antiviral, and prebiotic activities of dietary polysaccharides for the management of post-COVID-19 syndrome. Furthermore, the review investigates the role of polysaccharides in enhancing immune response, regulating immune function, improving oxidative stress, inhibiting virus binding to ACE2, balancing gut microbiota, and increasing functional metabolites. These properties of dietary polysaccharides may help alleviate COVID-19 symptoms, providing a promising avenue for effective treatment strategies.

Neuroprotection of low-molecular-weight galactan obtained from Cantharellus cibarius Fr. against Alzheimer's disease

The large molecular weight of polysaccharides limits their absorption and utilization by organisms, affecting their biological activities. In this study, we purified α-1,6-galactan from Cantharellus cibarius Fr. (chanterelle) and reduced its molecular weight from approximately 20 kDa to 5 kDa (named CCP) to increase its solubility and absorption. In APP/PS1 mice, CCP improved both spatial and non-spatial memory loss in Alzheimer's disease (AD) mice, as confirmed by the Morris water maze, step-down, step-through, and novel object recognition tests, and dampened the deposition of amyloid-β plaques, as assessed by immunohistochemical analysis. Proteomic analysis suggested that the neuroprotective effects of CCP are related to anti-neuroinflammation. Immunofluorescence analysis and western blotting confirmed that CCP attenuated AD-like symptoms partly by inhibiting neuroinflammation, which was related to the blocking of complement component 3. Our study provides theoretical support and experimental evidence for the future application of chanterelle-extracted polysaccharides in AD treatment, promoting the modern development of traditional medicines originating from natural polysaccharides.

Dietary Plant Polysaccharides for Cancer Prevention: Role of Immune Cells and Gut Microbiota, Challenges and Perspectives

Dietary plant polysaccharides, one of the main sources of natural polysaccharides, possess significant cancer prevention activity and potential development value in the food and medicine fields. The anti-tumor mechanisms of plant polysaccharides are mainly elaborated from three perspectives: enhancing immunoregulation, inhibiting tumor cell growth and inhibiting tumor cell invasion and metastasis. The immune system plays a key role in cancer progression, and immunomodulation is considered a significant pathway for cancer prevention or treatment. Although much progress has been made in revealing the relationship between the cancer prevention activity of polysaccharides and immunoregulation, huge challenges are still met in the research and development of polysaccharides. Results suggest that certain polysaccharide types and glycosidic linkage forms significantly affect the biological activity of polysaccharides in immunoregulation. At present, the in vitro anti-tumor effects and immunoregulation of dietary polysaccharides are widely reported in articles; however, the anti-tumor effects and in vivo immunoregulation of dietary polysaccharides are still deserving of further investigation. In this paper, aspects of the mechanisms behind dietary polysaccharides' cancer prevention activity achieved through immunoregulation, the role of immune cells in cancer progression, the role of the mediatory relationship between the gut microbiota and dietary polysaccharides in immunoregulation and cancer prevention are systematically summarized, with the aim of encouraging future research on the use of dietary polysaccharides for cancer prevention.

Mycochemicals against Cancer Stem Cells

Since ancient times, mushrooms have been considered valuable allies of human well-being both from a dietary and medicinal point of view. Their essential role in several traditional medicines is explained today by the discovery of the plethora of biomolecules that have shown proven efficacy for treating various diseases, including cancer. Numerous studies have already been conducted to explore the antitumoural properties of mushroom extracts against cancer. Still, very few have reported the anticancer properties of mushroom polysaccharides and mycochemicals against the specific population of cancer stem cells (CSCs). In this context, β-glucans are relevant in modulating immunological surveillance against this subpopulation of cancer cells within tumours. Small molecules, less studied despite their spread and assortment, could exhibit the same importance. In this review, we discuss several pieces of evidence of the association between β-glucans and small mycochemicals in modulating biological mechanisms which are proven to be involved with CSCs development. Experimental evidence and an in silico approach are evaluated with the hope of contributing to future strategies aimed at the direct study of the action of these mycochemicals on this subpopulation of cancer cells.

Preparation of Albatrellus ovinus β-Glucan Microparticles with Dectin-1a Binding Properties

Fungal β-glucans are compounds with the potential to activate the innate immune system, in part through binding to the receptor dectin-1. In the present study, small-scale methods for preparing dectin-1a binding microparticles from Albatrellus ovinus alkali-soluble β-glucans were investigated. Mechanical milling was time-consuming and yielded large particles with wide size distributions. Precipitation was more successful: the β-glucan was dissolved in 1 M NaOH, diluted, and precipitated in 1:1 mol equiv HCl. This yielded particles in sizes ranging from 0.5-2 μm. The dectin-1a binding activity was determined using HEK-Blue reporter cells. The prepared particles were able to bind to dectin-1a to the same extent as baker's-yeast-derived β-glucan particles. The precipitation method was convenient as a quick method for small-scale preparation of β-glucan microparticle dispersions from mushroom β-glucans.

Innate immune receptors co-recognition of polysaccharides initiates multi-pathway synergistic immune response

The law and mechanism of the interaction between polysaccharides and pattern recognition receptors (PRRs) has been unclear. Herein, three glucomannans with different structures were selected to explore the universal mechanism for PRRs to recognize glucomannans. Screening results showed that the silence of TLR4 but not TLR2 severely blocked the production of inflammatory cytokines and the transduction of signal pathways. In-depth results revealed that the participation of myeloid differentiation protein 2 (MD2) and CD14 and the dimerization of the TLR4-MD2 complex were required for glucomannan-activated TLR4 signal transduction. Mannose receptor (MR) was also engaged in glucomannan-induced respiratory burst, endocytosis, and inflammatory signaling pathways in a spleen tyrosine kinase-dependent manner. The internalization of glucomannans into the cytoplasm by MR directly initiated complex intracellular signaling cascades. Finally, molecular docking characterized the binding energy and binding sites between glucomannans and multiple receptors from other perspectives. The essence of glucomannans recognized by PRRs was the non-covalent interaction of multiple receptors and the subsequent transmission of the signal cascade was triggered in a multi-channel and cooperative manner. As a result, the hypothesis that "Innate immune receptors co-recognition of polysaccharides initiates multi-pathway synergistic immune response" was proposed to outline these meaningful phenomena.

Antioxidant Activity of Polysaccharides from the Edible Mushroom Pleurotus eryngii

In this study the antioxidant and neuroprotective activity of an enriched polysaccharide fraction (EPF) obtained from the fruiting body of cultivated P. eryngii was evaluated. Proximate composition (moisture, proteins, fat, carbohydrates and ash) was determined using the AOAC procedures. The EPF was extracted by using, in sequence, hot water and alkaline extractions followed by deproteinization and precipitation with cold ethanol. Total α- and β-glucans were quantified using the Megazyme International Kit. The results showed that this procedure allows a high yield of polysaccharides with a higher content of (1-3; 1-6)-β-D-glucans. The antioxidant activity of EPF was detected from the total reducing power, DPPH, superoxide, hydroxyl and nitric oxide radical scavenging activities. The EPF was found to scavenge DPPH, superoxide, hydroxyl and nitric oxide radicals with a IC50 values of 0.52 ± 0.02, 1.15 ± 0.09, 0.89 ± 0.04 and 2.83 ± 0.16 mg/mL, respectively. As assessed by the MTT assay, the EPF was biocompatible for DI-TNC1 cells in the range of 0.006-1 mg/mL and, at concentrations ranging from 0.05 to 0.2 mg/mL, significantly counteracted H₂O₂-induced reactive oxygen species production. This study demonstrated that polysaccharides extracted from P. eryngii might be used as functional food to potentiate the antioxidant defenses and to reduce oxidative stress.

Hypolipidemic mechanism of Pleurotus eryngii polysaccharides in high-fat diet-induced obese mice based on metabolomics

Objective

In this study, the structure of Pleurotus eryngii polysaccharides (PEPs) was characterized, and the mechanism of PEP on obesity and hyperlipidemia induced by high-fat diet was evaluated by metabonomic analysis.

Methods

The structure of PEPs were characterized by monosaccharide composition, Fourier transform infrared spectroscopy and thermogravimetry. In animal experiments, H&E staining was used to observe the morphological difference of epididymal adipose tissue of mice in each group. Ultrahigh performance liquid chromatography (UHPLC)-(QE) HFX -mass spectrometry (MS) was used to analyze the difference of metabolites in serum of mice in each group and the related metabolic pathways.

Results

The PEPs contained nine monosaccharides: 1.05% fucose, 0.30% arabinose, 17.94% galactose, 53.49% glucose, 1.24% xylose, 23.32% mannose, 1.30% ribose, 0.21%galacturonic acid, and 1.17% glucuronic acid. The PEPs began to degrade at 251°C (T0), while the maximum thermal degradation rate temperature (Tm) appeared at 300°C. The results histopathological observation demonstrated that the PEPs had signifificant hypolipidemic activities. After PEPs intervention, the metabolic profile of mice changed significantly. A total of 29 different metabolites were selected as adjunctive therapy to PEPs, for treatment of obesity and hyperlipidemia-related complications caused by a high-fat diet. These metabolites include amino acids, unsaturated fatty acids, choline, glycerol phospholipids, and other endogenous compounds, which can prevent and treat obesity and hyperlipidemia caused by a high-fat diet by regulating amino acid metabolism, fatty acid metabolism, and changes in metabolic pathways such as that involved in the citric cycle (TCA cycle).

Conclusions

The presented results indicate that PEPs treatment can alleviate the obesity and hyperlipidemia caused by a high-fat diet and, thus, may be used as a functional food adjuvant, providing a theoretical basis and technical guidance for the prevention and treatment of high-fat diet-induced obesity and hyperlipidemia.

Transglycosylation of Stevioside by a Commercial β-Glucanase with Fungal Extracted β-Glucans as Donors

Abstract

Alternative sweeteners, such as steviol glucosides from the plant Stevia rebaudiana Bertoni, are becoming increasingly popular for the design of next-generation foodstuffs. However, the bitter aftertaste of native steviol glucosides is one of the main reasons behind consumer reluctance towards stevia-containing products. Biocatalysis could be a sustainable solution to this problem, through addition of glucosyl moieties to the molecule. Glycoside hydrolases are enzymes performing transglycosylation reactions, and they can be exploited for such modifications. In the present work, the commercial β-glucanase Finizym 250L® was employed for the transglycosylation of stevioside. After optimization of several reaction parameters, the maximal reaction yield obtained was 19%, with barley β-glucan as the glycosyl donor. With the aim to develop a sustainable process, β-glucan extracts from different fungal sources were prepared. Pulsed Electric Field pretreatment of mycelial biomass resulted in extracts with higher β-glucan content. The extracts were tested as alternative glucosyl donors, reaching up to 15.5% conversion yield, from Pleurotus-extracted β-glucan. Overall, in the present work a novel enzymatic process for the modification of stevioside is proposed, with concomitant valorization of β-glucans extracted from fungal biomass, potentially generated as a byproduct from other applications, in concert with the principles of circular economy.

Graphical Abstract

Chemical characterization and biological effect of exopolysaccharides synthesized by Antarctic yeasts Cystobasidium ongulense AL101 and Leucosporidium yakuticum AL102 on murine innate immune cells

The current study aimed to investigate exopolysaccharides (EPSs) produced by two Antarctic yeasts isolated from soil and penguin feathers samples collected on Livingston Island (Antarctica). The strains were identified as belonging to the species Leucosporidium yakuticum (LY) and Cystobasidium ongulense (CO) based on molecular genetic analysis. The EPS production was investigated using submerged cultivation. Different chemical, chromatographic, and spectral analyses were employed to characterize EPSs. LY accumulated 5.5 g/L biomass and 4.0 g/L EPS after 120 h of cultivation, while CO synthesized 2.1 g/L EPS at the end of cultivation, and the biomass amount reached 5.5 g/L. LY-EPS was characterized by a higher total carbohydrate content (80%) and a lower protein content (18%) by comparison with CO-EPS (62%, 30%). The LY-EPS mainly consisted of mannose (90 mol%), whereas CO-EPS had also glucose, galactose, and small amounts of uronic acids (8-5 mol%). Spectral analyses (FT-IR and 1D, 2D NMR) revealed that LY-EPS comprised a typical β-(1 → 4)-mannan. Branched (hetero)mannan, together with β/α-glucans constituted the majority of CO-EPS. Unlike LY-EPS, which had a high percentage of high molecular weight populations, CO-EPS displayed a large quantity of lower molecular weight fractions and a higher degree of heterogeneity. LY-EPS (100 ng/mL) elevated significantly interferon gamma (IFN-γ) production in splenic murine macrophages and natural killer (NK) cells. The results indicated that newly identified EPSs might affect IFN-γ signaling and in turn, might enhance anti-infectious responses. The data obtained also revealed the potential of EPSs and yeasts for practical application in biochemical engineering and biotechnology.

The Structural Characterization and Immunomodulatory Activity of Polysaccharides from Pleurotus abieticola Fruiting Bodies

Polysaccharides obtained from mushrooms have been reported to possess immunomodulatory properties. In this study, a water-soluble polysaccharide was purified from the fruiting bodies of Pleurotus abieticola, entitled PAPS1. After its composition and structural analysis, the immunomodulatory activity was investigated in immunosuppressed mice induced by cyclophosphamide (CTX) at a dosage of 70 mg/kg by intraperitoneal injection for 7 days. After 28 days of intragastric administration, PAPS1 alleviated cyclophosphamide (CTX)-induced histopathological damage and increased the expressions of splenic CD4, CD8, CD56 and IgM in the serums of immunosuppressed mice. PAPS1 suppressed the oxidative stress indicated by preventing the increases in ROS and MDA levels. According to the intestinal microflora analysis, PAPS1 regulated 11 bacteria at the gene level, including Helicobacter and Paraprevotella, which are related to immunity and oxidative capacity. Compared with CTX-treated mice, significant increases in immune-related cytokines, such as interleukin (IL)-2, IL-6 and IL-12 in the serums of mice treated with PAPS1, were observed. Finally, PAPS1 can strongly increase the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its downstream proteins. In conclusion, PAPS1-boosted immunity may be related to its suppression on oxidative stress via enhancing the activity of Nrf2 signaling. Thus, PAPS1 can be investigated as a candidate for immunomodulatory therapy.

The discovery of novel immunomodulatory medicinal plants by combination of historical text reviews and immunological screening assays

ETHNOPHARMACOLOGICAL RELEVANCE

With the advent of immunotherapies against cancers, autoimmune diseases and infections, there is a steady demand for novel medicines. New sources for discovery of potentially novel immunomodulatory compounds are therefore needed. Nature contains a large and diverse reservoir of novel compounds that can be exploited for their potential as new drugs, and exploring the pharmaceutical potential of medicinal plants used in traditional medicine is highly relevant.

AIM OF THE STUDY

We aimed with this study to explore usage of medicinal plants in Scandinavian folk medicine against diseases interpreted to involve the immune system, and to further screen water extracts from previously overlooked medicinal plants in order to discover potential new sources of immunomodulatory compounds.

MATERIALS AND METHODS

We systematically investigated historical records dating back to the 1800s with an emphasis on plants used as treatment for wounds or diseases interpreted to be inflammatory. Of 74 candidate plants, 23 pharmacologically under-studied species were selected for further characterization. The plants were collected from their natural habitats in Southern Norway, air-dried, and subjected to boiling water and accelerated solvent extraction. The crude extracts were separated into polysaccharide-enriched fractions and C-18 solid phase extracted fractions. Immunological screenings were performed with all extracts and fractions. Monosaccharide composition and total phenolic content were determined and compared across all species.

RESULTS

We identified 10 species with clear immune activating effects and 8 species with immune inhibitory effects by comparing cytokine production by human peripheral blood mononuclear cells, primary human T- and NK-cell proliferation, and nitric oxide production from macrophages.

CONCLUSIONS

With this study, we provide a comprehensive overview of Scandinavian medicinal plants and their usage, and our findings support an approach of combining historical sources with modern pharmacology in the discovery of plant sources containing potentially new pharmacological compounds.

Immunoregulatory activity of a low-molecular-weight heteropolysaccharide from Ganoderma leucocontextum fruiting bodies in vitro and in vivo

The chemical structure of GLP-1, a novel water-soluble heteropolysaccharide purified Ganoderma leucocontextum fruiting bodies, has been characterized in our previous study. This study aimed to investigate the immunostimulatory activity of GLP-1 in vitro and in vivo by using RAW264.7 macrophages and cyclophosphamide-induced immunosuppressed mice model. Results showed that GLP-1 was able to enhance phagocytic activity and promote the production of reactive oxygen species, nitric oxide, tumor necrosis factor-α, interleukin-6, and monocyte chemoattractant protein-1 in RAW264.7 macrophages. Moreover, GLP-1 could activate mitogen-activated protein kinase, phosphatidylinositol-3-kinase/protein kinase B, and nuclear factor-kappa B signaling pathways through toll-like receptor 2 and dectin-1 receptors. Furthermore, GLP-1 increased the thymus index, serum immunoglobulin levels, and percentage of CD3⁺ T lymphocytes in cyclophosphamide-induced immunosuppressed mice. These results demonstrated that GLP-1 possessed significant immunostimulatory effects in vivo and in vitro and could be developed as an effective immunomodulator for application in functional foods.

Characterization on structure and bioactivities of an exopolysaccharide from Lactobacillus curvatus SJTUF 62116

This study aimed to investigate the chemical structure, physicochemical properties, antioxidant capacity, antibacterial ability and anti-biofilm formation activity of an exopolysaccharide (EPS) produced by Lactobacillus curvatus SJTUF 62116 from the fish Gymnocypris przewalskii. The purified EPS, denoted as EPS-1, was mainly composed of glucose and mannose at a relative molar ratio of 1:1.05 with molecular weight of 31.9 kDa. The chemical structure of EPS-1 was consisted of →2)-α-D-Manp-(1→, →4)-α-D-Manp-(1→, →3,6)-α-D-Manp-(1→, T-β-D-Glcp-(1→, →6)-β-D-Glcp-(1→, and →3)-β-D-Glcp-(1→ glycosidic bonds. A sheet-like structure of dried EPS-1 was determined by scanning electron microscope (SEM), whilst a peak-shaped structure of EPS-1 was observed by atomic force microscope (AFM). The degradation temperature of EPS-1 was determined as 300.21 °C using thermogravimetric analysis (TGA). Moreover, the antioxidant capacity of EPS-1 at a concentration of 5.0 mg/mL against DPPH and ABTS was 84.50% and 92.53%, respectively. Furthermore, EPS-1 exhibited acceptable bacteriostatic efficacy against S. Enteritidis, E. coli, and S.aureus with significant inhibition of S. Enteritidis biofilm formation.

β-Glucans from Yeast—Immunomodulators from Novel Waste Resources

β-glucans are a large class of complex polysaccharides with bioactive properties, including immune modulation. Natural sources of these compounds include yeast, oats, barley, mushrooms, and algae. Yeast is abundant in various processes, including fermentation, and they are often discarded as waste products. The production of biomolecules from waste resources is a growing trend worldwide with novel waste resources being constantly identified. Yeast-derived β-glucans may assist the host’s defence against infections by influencing neutrophil and macrophage inflammatory and antibacterial activities. β-glucans were long regarded as an essential anti-cancer therapy and were licensed in Japan as immune-adjuvant therapy for cancer in 1980 and new mechanisms of action of these molecules are constantly emerging. This paper outlines yeast β-glucans’ immune-modulatory and anti-cancer effects, production and extraction, and their availability in waste streams.

Characterization of polysaccharide from Pleurotus eryngii during simulated gastrointestinal digestion and fermentation

Pleurotus eryngii is a valuable new edible mushroom variety cultivated on a large scale in China. The polysaccharides found in this mushroom are strong bioactive. This study used simulated digestion and fermentation model to study the digestion and fermentation characteristics of Pleurotus eryngii polysaccharide (PEP) and its effect on gut microbiota. The results showed that the molecular weight of PEP remained unchanged after simulated digestion, and the overall structure of PEP was not destroyed, indicating that PEP was not decomposed during digestion. However, during fermentation, PEP was degraded and utilized by intestinal flora to produce a variety of short-chain fatty acids (SCFAs), which reduced the pH value in fecal cultures. Meanwhile, PEP regulated the composition of intestinal flora, and the relative abundance of Firmicutes increased significantly. These suggests that PEP can be used as a functional food to promote intestinal health and prevent disease.

Structural Characterization and Anticoagulant Activity of a 3-O-Methylated Heteroglycan From Fruiting Bodies of Pleurotus placentodes

Pleurotus placentodes, a fungus, belongs to the Pleurotaceae family. The aim of the present study was to characterize the structure of a novel polysaccharide from fruiting bodies of P. placentodes (PPp-W) and evaluate its anticoagulant activity in vitro. The high-performance liquid chromatography and GC–MS analysis indicated that PPp-W with a molecular weight of 27.4 kDa was mainly composed of mannose (17.56%), glucose (6.37%), galactose (44.89%), and fucose (1.22%) with a certain amount of 3-O-methyled galactose. SEM, XRD, and AFM combined with Congo red test revealed that PPp-W was an irregular curly sheet with triple-helix conformation. The FT-IR, methylation, and nuclear magnetic resonance analysis indicated that PPp-W contained→6)-α-D-Galp-(1→, →6)-3-O-Me-α-D-Galp-(1→and →2, 6)-α-D-Galp-(1→ as main chain, partially substituted at O-2 and O-6 by non-reducing ends of β-D-Manp-(1→ and β-L-Fucp-(1→ with a small amount of α-1,3-linked-Glcp in backbone. PPp-W could significantly prolong APTT (12.9 ± 0.42 s, p < 0.001) and thrombin time (39.9 ± 0.28 s, p < 0.01) compared with the control group (11.45 ± 0.071 s and 38.05 ± 0.21 s), which showed that PPp-W had anticoagulant activity. These studies suggested that PPp-W was a 3-O-methylated heteroglycan and might be suitable for functional foods and natural drugs as an anticoagulant ingredient, which provided a basis for the application of polysaccharides from P. placentodes.

Understanding immune-modulatory efficacy in vitro

Boosting or suppressing our immune system represents an attractive adjunct in the treatment of infections including SARS-CoV-2, cancer, AIDS, malnutrition, age related problems and some inflammatory disorders. Thus, there has been a growing interest in exploring and developing novel drugs, natural or synthetic, that can manipulate our defence mechanism. Many of such studies, reported till date, have been designed to explore effect of the therapeutic on function of macrophages, being a key component in innate immune system. Indeed, RAW264.7, J774A.1, THP-1 and U937 cell lines act as ideal model systems for preliminary investigation and selection of dose for in vivo studies. Several bioassays have been standardized so far where many techniques require high throughput instruments, cost effective reagents and technical assistance that may hinder many scholars to perform a method demanding compilation of available protocols. In this review, we have taken an attempt for the first time to congregate commonly used in vitro immune-modulating techniques explaining their principles. The study detected that among about 40 different assays and more than 150 sets of primers, the methods of cell proliferation by MTT, phagocytosis by neutral red, NO detection by Griess reaction and estimation of expression of TLRs, COX-2, iNOS, TNF-α, IL-6 and IL-1β by PCR have been the most widely used to screen the therapeutics under investigation.

A synbiotic containing prebiotic prepared from a by-product of king oyster mushroom, Pleurotus eryngii and probiotic, Lactobacillus plantarum incorporated in diet to improve the growth performance and health status of white shrimp, Litopenaeus vannamei

This study aimed to evaluate the effects of a synbiotic composite an extract from a by-product of king oyster mushroom, Pleurotus eryngii (KOME), and probiotic Lactobacillus plantarum 7-40 on the growth performance and health status of white shrimp, Litopenaeus vannamei. The KOME was able to stimulate the growth of probiotic, but not the growth of Vibrio pathogens, including V. alginolyticus, V. parahaemolyticus, and V. harveyi. Four diets were formulated, including a control diet supplemented without prebiotic and probiotic, a basal diet supplemented with KOME (5 g kg^-1) (ME), a basal diet supplemented with probiotic (1 × 10⁸ CFU kg^-1) (LP), and a basal diet supplemented with KOME (5 g kg^-1) and probiotic (1 × 10⁸ CFU kg^-1) (SYN). Shrimp fed the ME, LP, and SYN diets had significantly higher survival than that of shrimp fed with the control diet for 8 weeks. Shrimp in the SYN group also had a significantly higher weight gain and total final weight in comparison with the control and other treatments. In the intestinal tract, lactic acid bacteria count was significantly higher in the SYN group, whereas the Vibrio-like bacteria count was significantly higher in the ME group than in the control group. For the health status assessment, the disease resistance of shrimp against V. alginolyticus was improved in all treatments compared to the shrimp in control. Shrimps in the SYN group had significantly lower cumulative mortality due to the significant increase in immune responses, including phenoloxidase, respiratory burst, and lysozyme activity, and the gene expression of pexn and pen4 in the haemocytes, and lgbp, sp, propoii, pexn, pen3a, pen4, and gpx in the haepatopancreas of shrimp as compared to the control. Therefore, it is suggested that a combination of KOME and probiotics can be used as a synbiotic to improve the growth performance and reduce the risk of infectious diseases caused by Vibrio and at the same time significantly contribute to the circular economy.