Extraction, purification, bioactivities and prospect of lentinan: A review

Immunogenic cell death inducers for cancer therapy: An emerging focus on natural products

BACKGROUND

Immunogenic cell death (ICD) is a specific form of regulated cell death induced by a variety of stressors. During ICD, the dying cancer cells release damage-associated molecular patterns (DAMPs), which promote dendritic cell maturation and tumor antigen presentation, subsequently triggering a T-cell-mediated anti-tumor immune response. In recent years, a growing number of studies have demonstrated the potential of natural products to induce ICD and enhance tumor cell immunogenicity. Moreover, there is an increasing interest in identifying new ICD inducers from natural products.

PURPOSE

This study aimed to emphasize the potential of natural products and their derivatives as ICD inducers to promote research on using natural products in cancer therapy and provide ideas for future novel immunotherapies based on ICD induction.

METHOD

This review included a thorough search of the PubMed, Web of Science, Scopus, and Google Scholar databases to identify natural products with ICD-inducing capabilities. A comprehensive search for clinical trials on natural ICD inducers was also conducted using ClinicalTrials.gov, as well as the approved patents using the Espacenet and CNKI Patent Database.

RESULTS

Natural compounds that induce ICD can be categorized into several groups, such as polyphenols, flavonoids, terpenoids, and alkaloids. Natural products can induce the release of DAMPs by triggering endoplasmic reticulum stress, activation of autophagy-related pathways, and reactive oxygen species generation, etc. Ultimately, they activate anti-tumor immune response and improve the efficacy of cancer treatments.

CONCLUSION

A growing number of ICD inducers from natural products with promising anti-cancer potential have been identified. The detailed information presented in this review will contribute to the further development of natural ICD inducers and cancer treatment strategies based on ICD-induced responses.

Lipid metabolism regulation by dietary polysaccharides with different structural properties

Lipid metabolism plays an important role in energy homeostasis maintenance in response to stress. Nowadays, hyperlipidemia-related chronic diseases such as obesity, diabetes, atherosclerosis, and fatty liver pose significant health challenges. Dietary polysaccharides (DPs) have gained attention for their effective lipid-lowering properties. This review examines the multifaceted mechanisms that DPs employ to lower lipid levels in subjects with hyperlipidemia. DPs could directly inhibit lipid intake and absorption, promote lipid excretion, and regulate key enzymes involved in lipid metabolism pathways, including triglyceride and cholesterol anabolism and catabolism, fatty acid oxidation, and bile acid synthesis. Additionally, DPs indirectly improve lipid homeostasis by modulating gut microbiota composition and alleviating oxidative stress. Moreover, the lipid-lowering mechanisms of particular structural DPs (including β-glucan, pectin, glucomannan, inulin, arabinoxylan, and fucoidan) are summarized. The relationship between the structure and lipid-lowering activity of DPs is also discussed based on current researches. Finally, potential breakthroughs and future directions in the development of DPs in lipid-lowering activity are discussed. The paper could provide a reference for further exploring the mechanism of DPs for lipid regulations and utilizing DPs as lipid-lowering dietary ingredients.

Extraction of Lentinus Edodes Polysaccharides with Ultrasound Enhanced with Deep Eutectic Solvent and Their Structural Characterization and Antioxidant Activity

Ultrasound extraction (UE) enhanced with deep eutectic solvent (DES) was used to extract Lentinus edodes polysaccharides. Box-Behnken design (BBD) was applied to investigate the influences of water content (10-90 %), solid-liquid solvent (1 : 10-1 : 50 g/mL), time (4-12 min), temperature (40-80 °C) and ultrasonic power (100-500 W) on the yield of Lentinus edodes polysaccharides. The optimal extraction conditions were ultrasonic power of 300 W, extraction time of 8 min, water content of 80 %, a solid-liquid ratio of 1 : 30 g/mL and a temperature of 60 °C, respectively. The highest extraction yield of Lentinus edodes polysaccharide was 10.17 % under optimal conditions. The results of FT-IR, SEM, and monosaccharide composition confirmed that the extracts possessed the characteristics of polysaccharides. In addition, the polysaccharides obtained with the UE enhanced with DES method exhibited higher antioxidant activities than the polysaccharides extracted with the UE method and HWE method. This extraction method can further expand the production efficiency and structural diversity of Lentinus edodes polysaccharides and meet the supply and demand relationship. It can be foreseen that this method can be applied to the extraction of more active substances.

Current Advances in the Functional Genes of Edible and Medicinal Fungi: Research Techniques, Functional Analysis, and Prospects

Functional genes encode various biological functions required for the life activities of organisms. By analyzing the functional genes of edible and medicinal fungi, varieties of edible and medicinal fungi can be improved to enhance their agronomic traits, growth rates, and ability to withstand adversity, thereby increasing yield and quality and promoting industrial development. With the rapid development of functional gene research technology and the publication of many whole-genome sequences of edible and medicinal fungi, genes related to important biological traits have been mined, located, and functionally analyzed. This paper summarizes the advantages and disadvantages of different functional gene research techniques and application examples for edible and medicinal fungi; systematically reviews the research progress of functional genes of edible and medicinal fungi in biological processes such as mating type, mycelium and fruit growth and development, substrate utilization and nutrient transport, environmental response, and the synthesis and regulation of important active substances; and proposes future research directions for functional gene research for edible and medicinal fungi. The overall aim of this study was to provide a valuable reference for further promoting the molecular breeding of edible and medicinal fungi with high yield and quality and to promote the wide application of edible and medicinal fungi products in food, medicine, and industry.

The effect of lentinan on dexamethasone-induced immunosuppression in mice

The immune system acts as a vital defense barrier against pathogenic invasions, and its stable operation is crucial for maintaining body health. Nevertheless, various natural or artificial factors can compromise the body's immune function, leading to immunosuppression, which may interfere with the efficacy of vaccination and increase the susceptibility of the body to disease-causing pathogens. In an effort to ensure successful vaccinations and improve overall physical well-being, the search for appropriate immune regulators to enhance immunity is of paramount importance. Lentinan (LNT) has a significant role in immune regulation and vaccine adjuvants. In the present study, we constructed an immunosuppressive model using dexamethasone (DEX) and demonstrated that LNT could significantly improved antibody levels in immunosuppressive mice and stimulated T-lymphocyte proliferation and differentiation in intestinal Peyer's patches. LNT also increased the production of secretory immunoglobulin A (sIgA) in the duodenal fluid, the number of goblet cells, and the proportion of mucin area. Moreover, LNT modulated the intestinal microbiota and increased the production of short-chain fatty acids. Additionally, LNT promoted the proliferation, differentiation, and pro-inflammatory cytokines production of DEX-treated splenic T lymphocytes in vitro. Thus, the present study highlights the potential of LNT in reversing immunosuppression and avoiding the failure of vaccination.

Changes in flavor and biological activities of Lentinula edodes hydrolysates after Maillard reaction

This study aimed to elucidate how the Maillard reaction (MR) affects the flavor and bioactivities of Lentinula edodes hydrolysates (LEHs). Changes in flavor were investigated using non-targeted metabolomics techniques (GC-MS and LC-MS/MS) and sensory evaluation. Simultaneously, UV absorption, fluorescence, and FT-IR spectra were used to characterize the process of MR. We also evaluated the effects of MR on the antioxidant activity, hypoglycemic activity and antimicrobial activity of LEHs in vitro. The results revealed that MR produced many volatile aldehydes and ketones and decreased the content of most amino acids, sugars and flavonoids in the LEHs while increasing the content of l-theanine and succinic acid. MRPs had a strong caramel and like-meat flavor and an obvious improvement in umami, taste continuity, and total acceptability. Furthermore, MR improved the antioxidant and antimicrobial properties of LEHs. This research establishes a theoretical foundation for MR in the deep processing of edible mushrooms.

Natural deep eutectic solvents for the extraction of lentinan from shiitake mushroom: COSMO-RS screening and ANN-GA optimizing conditions

Using natural deep eutectic solvents (NDES) for green extraction of lentinan from shiitake mushroom is a high-efficiency method. However, empirical and trial-and-error methods commonly used to select suitable NDES are unconvincing and time-consuming. Conductor-like screening model for realistic solvation (COSMO-RS) is helpful for the priori design of NDES by predicting the solubility of biomolecules. In this study, 372 NDES were used to evaluate lentinan dissolution capability via COSMO-RS. The results showed that the solvent formed by carnitine (15 wt%), urea (40.8 wt%), and water (44.2 wt%) exhibited the best performance for the extraction of lentinan. In the extraction stage, an artificial neural network coupled with genetic algorithm (ANN-GA) was developed to optimize the extraction conditions and to analyze their interaction effects on lentinan content. Therefore, COSMO-RS and ANN-GA can be used as powerful tools for solvent screening and extraction process optimization, which can be extended to various bioactive substance extraction.

Atomic force microscopy based conformation and immunological activity of Lentinan injections

The purpose of this study was to investigate the morphological characteristics of different brands of lentinan injections produced in China using atomic force microscopy (AFM) and their relationship to immunological activity. Based on AFM imaging, chain height could be used as characterizing the conformation of lentinan, and the heights of 95 % confidence interval for triple, double and single helix were 1.746 ± 0.039 nm, 1.564 ± 0.037 nm and 1.243 ± 0.031 nm, respectively, which were calculated using self-developed MATLAB protocol. AFM characters and their immunological activity of different lentinan injection were compared. In detail, two parameters, triple helix ratio 51.3 % and adhesion force 800 pN, of Jinling (JL) lentinan injection are much higher than samples of other four manufacturers. In addition, immunological activity of JL lentinan injection is also significantly higher than Yineng's. High performance size exclusion chromatography (HPSEC) profiles of different lentinans were also compared, and the data were in accordance with those from AFM. Molecular weight accumulation curves could be used for evaluation of quality consistence of different batches of lentinan from same manufacturer and/or different manufacturers. The results showed that quality consistence of lentinan from different manufactures is poor, which should be greatly improved.

The physicochemical, antioxidant, hypoglycemic and prebiotic properties of γ-irradiated polysaccharides extracted from Lentinula edodes

In this study, the influence of γ-irradiation with different dose (0, 4, 8, and 16 kGy) on chemical composition, physicochemical features and bioactivities of polysaccharides extracted from Lentinula edodes (LEP) were investigated. The carbohydrate content (from 59.47 to 70.96%), the solubility, the ⋅OH and DPPH scavenging ability of LEP increased with the increased γ-irradiation dose, while the protein content, the weight-average and number-average molecular weight of LEP were significantly decreased with the increased γ-irradiation dose. Moreover, γ-irradiation treatment caused LEP color changes and surface topography destroyed. γ-Irradiated LEP showed higher hypoglycemic activities in vitro than that of non-irradiated LEP. Moreover, γ-irradiated LEP had better proliferation promoting effects on Lactobacillus rhamnosus and L. plantarum. These results showed that γ-irradiation treatment changes the physicochemical features of LEP, thus affects its antioxidant, hypoglycemic and prebiotic properties, which suggests that γ-irradiated LEP has potential application in the pharmaceutical industries and functional foods.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-022-01234-5.

Biopharmaceutical applications of microbial polysaccharides as materials: A review

Biological characteristics of natural polymers make microbial polysaccharides an excellent choice for biopharmaceuticals. Due to its easy purifying procedure and high production efficiency, it is capable of resolving the existing application issues associated with some plant and animal polysaccharides. Furthermore, microbial polysaccharides are recognized as prospective substitutes for these polysaccharides based on the search for eco-friendly chemicals. In this review, the microstructure and properties of microbial polysaccharides are utilized to highlight their characteristics and potential medical applications. From the standpoint of pathogenic processes, in-depth explanations are provided on the effects of microbial polysaccharides as active ingredients in the treatment of human diseases, anti-aging, and drug delivery. In addition, the scholarly developments and commercial applications of microbial polysaccharides as medical raw materials are also discussed. The conclusion is that understanding the use of microbial polysaccharides in biopharmaceuticals is essential for the future development of pharmacology and therapeutic medicine.

Food By-Products and Agro-Industrial Wastes as a Source of β-Glucans for the Formulation of Novel Nutraceuticals

Food and agro-industrial by-products provoke a great environmental and economic impact that must be minimized by adding value to these wastes within the framework of circular economy. The relevance of β-glucans obtained from natural sources (cereals, mushrooms, yeasts, algae, etc.), in terms of their interesting biological activities (hypocholesterolemic, hypoglycemic, immune-modulatory, antioxidant, etc.), has been validated by many scientific publications. Since most of these by-products contain high levels of these polysaccharides or can serve as a substrate of β-glucan-producing species, this work reviewed the scientific literature, searching for studies that utilized food and agro-industrial wastes to obtain β-glucan fractions, attending to the applied procedures for extraction and/or purification, the characterization of the glucans and the tested biological activities. Although the results related to β-glucan production or extraction using wastes are promising, it can be concluded that further research on the glucans’ characterization, and particularly on the biological activities in vitro and in vivo (apart from antioxidant capacity), is required to reach the final goal of formulating novel nutraceuticals based on these molecules and these raw materials.

Effects of molecular weight on intestinal anti-inflammatory activities of β-D-glucan from Ganoderma lucidum

To investigate the influence of molecular weight (Mw) on the anti-inflammatory activity of β-D-glucan from Ganoderma lucidum, ultrasonic irradiation was applied to treat the β-D-glucan (GLP, 2.42 × 106 g/mol) solution to obtain two degraded fractions with molecular weight of 6.53 × 105 g/mol (GLPC) and 3.49 × 104 g/mol (GLPN). Structural analysis proved that the degraded fractions possessed similar repeated units with the original β-D-glucan. The in vitro anti-inflammatory activity studies showed that all fractions could significantly inhibit LPS-induced expression of cytokines including TNF-α, IL-8, MIF and MCP-1 in Caco-2 cells at certain concentrations. Moreover, GLPC and GLPN exhibited better anti-inflammatory activity than GLPC. The intestinal anti-inflammatory activity evaluated by dextran sulfate sodium (DSS)—induced colitis mice model showed that intragastric administration of GLPN (lower Mw fraction) could significantly recover inflamed tissues of mice. Compared with GLP and GLPC, GLPN exhibited stronger ability to inhibit the secretion of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). The results revealed that Mw of β-D-glucan influenced its anti-inflammatory activity and decreasing of Mw would improve the activity, which provided evidence for the potential use of β-D-glucan from G. lucidum as anti-colitis ingredients.

Galactofuranose side chains in galactomannans from Penicillium spp. modulate galectin-8-mediated bioactivity

Polysaccharides from fungi have many bioactivities. Previous studies showed that galactomannans from Penicillium oxalicum antagonize galectin-8-mediated activity. Here, two intracellular and two extracellular galactomannans were purified and their structures were comparatively characterized by NMR, partial acid hydrolysis and methylation. All four of them were identified to be galactomannans with similar mannan backbones having 1,2-/1,6-linkages (~3:1) and various amounts of galactofuranan side chains. The interaction of those polysaccharides with galectin-8 was assessed by hemagglutination and biolayer interferometry. These results show that side chains are important for the interaction, and the more the side chains, the stronger the interaction. But the side chains alone did not show act on galectin-8, which indicated that the cooperation between backbone and side chains is another necessary factor for this interaction. Our findings provide important information about structure-activity relationships and the galactofuranose-containing galactomannans might be as potential therapeutic of galectin-8 related diseases.

Effects of Ultrasound Modification with Different Frequency Modes on the Structure, Chain Conformation, and Immune Activity of Polysaccharides from Lentinus edodes

Highlights

Abstract

The aim of this study was to investigate the effects of ultrasound with different frequency modes on the chemical structure, chain conformation, and immune activity of lentinan from Lentinus edodes; the structure–activity relationship of lentinan was also discussed. The results showed that, compared with original lentinan (extracted using hot water), although ultrasonic treatment did not change the monosaccharide composition and main functional groups of lentinan, it significantly changed its chain conformation. Especially at 60, 40/60, and 20/40/60 kHz, according to atomic force microscopy and solution chain conformation parameters, lentinan transformed from a rigid triple-helix chain to a flexible single-helix chain, and the side-chain was severely broken. Under this condition, lentinan had the worst immune activity. However, at 20/40 and 20/60 kHz, the rigid triple-helix chain transformed into a loose and flexible triple-helix chain, showing the strongest immune activity. These results indicated that dual-frequency ultrasound had significant effects on the conformation of lentinan, and the conformation characteristics of polysaccharide chain such as spiral number, stiffness and flexibility, and side-chain played an important role in immune activity. This study shows the great potential of ultrasound with different frequency modes in carbohydrate food processing, which may have important reference value and practical significance.

Extraction, purification, structural characterization, and gut microbiota relationship of polysaccharides: A review

Intestinal dysbiosis is one of the major causes of the occurrence of metabolic syndromes, such as obesity, diabetes, nonalcoholic fatty liver disease, and cardiovascular diseases. Polysaccharide-based microbial therapeutic strategies have excellent potential in the treatment of metabolic syndromes, but the underlying regulatory mechanisms remain elusive. Identification of the internal regulatory mechanism of the gut microbiome and the interaction mechanisms involving bacteria and the host are essential to achieve precise control of the gut microbiome and obtain valuable clinical data. Polysaccharides cannot be directly digested; the behavior in the intestinal tract is considered a "bridge" between microbiota and host communication. To provide a relatively comprehensive reference for researchers in the field, we will discuss the polysaccharide extraction and purification processes and chemical and structural characteristics, focusing on the polysaccharides in gut microbiota through the immune system, gut-liver axis, gut-brain axis, energy axis interactions, and potential applications.

Rheological properties of polysaccharides from Pholiota nameko with different temperature extraction: Concentration, pH, temperature, and saltion

Cold and hot water extracted polysaccharides (CW-PNPs and HW-PNPs) were isolated from Pholiota nameko. The rheological properties of PNPs were investigated by steady shear and oscillatory rheological measurements. The PNPs exhibited typical non-Newtonian and shear-thinning behavior, which are affected by PNP concentration, temperature, pH value, salt ion, and concentration. Specifically, the apparent viscosity of the two PNPs solutions at concentration of 1% (w/w) was shown as HW-PNPs > CW-PNPs. The apparent viscosity of PNPs decreases under acidic and alkaline conditions and when the temperature rises; K⁺ and Na⁺ cause the apparent viscosity of CW-PNPs to decrease, while Ca²⁺ and Al³⁺ are opposite. The addition of four different salt ions all caused the apparent viscosity of the HW-PNPs to decrease. The results of dynamic rheological experiments show that G' and G″ showed slightly frequency dependency with G' exceeding G″ throughout the accessible range of frequency for CW-PNPs and HW-PNPs.

Effects of fermentation with Lactobacillus fermentum 21828 on the nutritional characteristics and antioxidant activity of Lentinus edodes liquid

BACKGROUND

Few studies to date have evaluated the use of Lactobacillus and Bifidobacterium in edible fungus fermentation. To obtain a fermented Lentinus edodes liquid product with good taste and effects, a strain with good fermentation performance from nine strains tested was selected, and the physicochemical properties and antioxidant capacity of the resulting product were evaluated.

RESULTS

Lactobacillus fermentum 21828 exhibited adhesion, tolerance to low pH and bile salts, and good fermentation performance. The number of viable bacteria was 1.05 × 10⁸  CFU mL^-1 , and the extraction rate of crude polysaccharide from L. edodes was 2.79% after fermentation. The effects of fermentation on the contents and composition of nutrients in L. edodes liquid were marked, with changes in total soluble protein, total soluble sugar, total acid, and total phenol levels. The 2,2-diphenyl-1-picrylhydrazyl radical-scavenging rate in the fermentation liquid was 93.01%, which was significantly higher than that in non-fermented liquid (80.33%). Furthermore, analysis of volatile and 5'-nucleotide contents showed that fermentation altered the flavor of the product, whereas sensory evaluation showed that the fermented product was preferred.

CONCLUSION

Our study demonstrated that the fermented L. edodes liquid exhibited better nutritional and functional properties, as well as sensory characteristics, compared with unfermented liquid. © 2021 Society of Chemical Industry.