The effect of fermentation conditions on the structure and anti-tumor activity of polysaccharides from Cordyceps gunnii

A structure-functionality insight into the bioactivity of microbial polysaccharides toward biomedical applications: A review

Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

The function and application of edible fungal polysaccharides

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

Antitumor effects of polysaccharides from medicinal lower plants: A review

Cancer is one of the leading causes of death worldwide, yet the drugs currently approved for cancer treatment are associated with significant side effects, making it urgent to develop alternative drugs with low side effects. Polysaccharides are natural polymers with ketone or aldehyde groups, which are widely found in plants and have various biological activities such as immunomodulation, antitumor and hypolipidemic. The lower plants have attracted much attention for their outstanding anticancer effects, and many studies have shown that medicinal lower plant polysaccharides (MLPPs) have antitumor activity against various cancers and are promising alternatives with potential development in the food and pharmaceutical fields. Therefore, this review describes the structure and mechanism of action of MLPPs with antitumor activity. In addition, the application of MLPPs in cancer treatment is discussed, and the future development of MLPPs is explored.

Mycelial biomass and intracellular polysaccharides production, characterization, and activities in Auricularia auricula-judae cultured with different carbon sources

The carbon source, an essential factor for submerged culture, affects fungal polysaccharides production, structures, and activities. This study investigated the impact of carbon sources, including glucose, fructose, sucrose, and mannose, on mycelial biomass and the production, structural characterization, and bioactivities of intracellular polysaccharides (IPS) produced by submerged culture of Auricularia auricula-judae. Results showed that mycelial biomass and IPS production varied with different carbon sources, where using glucose as the carbon source produced the highest mycelial biomass (17.22 ± 0.29 g/L) and IPS (1.62 ± 0.04 g/L). Additionally, carbon sources were found to affect the molecular weight (Mw) distributions, monosaccharide compositions, structural characterization, and activities of IPSs. IPS produced with glucose as the carbon source exhibited the best in vitro antioxidant activities and had the strongest protection against alloxan-damaged islet cells. Correlation analysis revealed that Mw correlated positively with mycelial biomass (r = 0.97) and IPS yield (r = 1.00), while IPS antioxidant activities correlated positively with Mw and negatively with mannose content; the protective activity of IPS was positively related to its reducing power. These findings indicate a critical structure-function relationship for IPS and lay the foundation for utilizing liquid-fermented A. aruicula-judae mycelia and the IPS in functional food production.

Contribution of Quercetin to the Composition and Antioxidant Properties of Monascus Exopolysaccharides

Exopolysaccharides are important metabolites of Monascus with healthy activities. However, the low production level limits their applications. Hence, the aim of this work was to increase the yield of exopolysaccharides (EPS) and optimize liquid fermentation by adding flavonoids. The EPS yield was optimized via both medium composition and culture conditions. The optional fermentation conditions achieved for EPS production of 7.018 g/L were 50 g/L sucrose, 3.5 g/L yeast extract, 1.0 g/L MgSO₄·7H₂O, 0.9 g/L KH₂PO₄, 1.8 g/L K₂HPO₄·3H₂O, 1 g/L quercetin, and 2 mL/L Tween-80, with pH 5.5, inoculum size 9%, seed age 52 h, shaking speed 180 rpm, and fermentation culture 100 h, respectively. Furthermore, the addition of quercetin increased EPS production by 11.66%. The results also showed little citrinin residue in the EPS. The exopolysaccharides' composition and antioxidant capacity of quercetin-modified exopolysaccharides were then preliminarily investigated. The addition of quercetin changed the composition of the exopolysaccharides and the molecular weight (Mw). In addition, the antioxidant activity of Monascus exopolysaccharides was monitored using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS⁺), and -OH. Monascus exopolysaccharides have good scavenging ability of DPPH and -OH. Furthermore, quercetin increased the scavenging ABTS+ ability. Overall, these findings provide a potential rationale for the application of quercetin in improving the EPS yield.

Activities and metabolomics of Cordyceps gunnii under different culture conditions

Many active metabolites have been identified from various species of the fungal genus Cordyceps. A predominant species of this genus is Cordyceps gunnii, but there are limited reports on the active ingredients from this species. This study aimed to conduct activity assays and metabolome analysis on extracts of C. gunnii obtained under different culture conditions. Five different solid media were selected to culture the mycelium of C. gunnii and the metabolites were extracted with organic solvents; concurrently, the wild stroma and host complexes of C. gunnii were extracted by ethyl acetate. Extracts were subsequently assayed for various biological activities and were analyzed by untargeted metabolomics. There were significant differences in the activities and metabolites of C. gunnii extracts from different culture conditions and from wild stroma and host complexes. The extracts of stroma and host complexes and mycelia cultured on WGA medium for 21 days exhibited similar effective inhibitory activity against five cell lines. A total of 51 metabolites were annotated and included various structural types. The literatures indicate that most of the identified compounds have a variety of different biological activities. These findings provide the basis for further systematic excavation of C. gunnii and improved utilization of this fungal species.

Genomic Sequence and Transcriptome Analysis of the Medicinal Fungus Keithomyces neogunnii

The filamentous fungus Keithomyces neogunnii can infect the larvae of Lepidoptera (Hepialus sp.) and form an insect-fungi complex, which is utilized as an important traditional Chinese medicine. As a valuable medicinal fungus, K. neogunnii produces diverse bioactive substances (e.g., polysaccharide, vitamins, cordycepic acid, and adenosine) under cultivation conditions. Herein, we report the first high-quality genome of the K. neogunnii single-spore isolate Cg7.2a using single-molecule real-time sequencing technology in combination with Illumina sequencing. The assembled genome was 32.6 Mb in size, containing 8,641 predicted genes and having a GC content of 52.16%. RNA sequencing analysis revealed the maximum number of differentially expressed genes in the fungus during the stroma formation stage compared with those during the mycelium stage. These data are valuable to enhance our understanding of the biology, development, evolution, and physiological metabolism of K. neogunnii.

Role of genistein on the yield, structure and immunomodulatory activity of Monascus exopolysaccharides

Manipulating the structures, physicochemical properties, and monosaccharide compositions of exopolysaccharides (EPS) isolated from microorganisms has been reported to enhance their biological activities. Hence, the aim of this work was to examine the effects of genistein addition during fermentation on the amount, physicochemical properties, and immunomodulatory activity of EPS secreted by M. purpureus. Results showed that genistein addition significantly increased M. purpureus biomass and EPS yield to 2.42 g L^-1 and 6.08 g L^-1, respectively, and affected the physicochemical properties and structures of EPS. Furthermore, EPS produced by genistein-treated M. purpureus (G-EMP) improved the immunomodulatory activity of RAW264.7 macrophages by increasing the secretion of nitric oxide and cytokines. Moreover, phospho-Jun N-terminal kinase (p-JNK), phospho-extracellular regulated protein kinase (p-ERK), phospho-p38 (p-p38) mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) phospho-p65 (p65) proteins were remarkably upregulated by G-EMP stimulation, blocking Toll-like receptor 4 (TLR4) that dramatically reduced the pinocytic and phagocytic capacities. Overall, these findings provide potential rationales for the application of genistein in improving the EPS yield of M. purpureus.

Studies on characteristics and anti-diabetic and -nephritic effects of polysaccharides isolated from Paecilomyces hepiali fermentation mycelium in db/db mice

Type 2 diabetes mellitus plagues many people in China and the world, and its nephritis complication is the leading cause of death for patients. Paecilomyces hepiali contained various functional components, especially polysaccharides, which possesses well pharmacological activities. In this study, polysaccharide purified from Paecilomyces hepiali fermented mycelium entitled PHEA was obtained, and its structure was systemically characterized using fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR). In C57BL/KsJ (BKS).Cg-Dock7^m +/+ Lepr^db/JNju mice (db/db mice), via detecting the alternations on biochemical criterions, pathological indicators and protein expressions related to nuclear factor-E2-related factor 2 (Nrf2) and nuclear factor-κB (NF-κB) signaling in serum and/or tissues including muscle, liver and kidney after 8-week PHEA administration, the hypoglycemic, hypolipidemic, and anti-diabetic nephropathic activities of PHEA were confirmed. The purified P. Hepiali polysaccharide with the anti-diabetic and -nephritic properties was first reported in this study via regulating Nrf2-meadited NF-κB signaling in db/db mice.