Structural properties and antioxidant activities of polysaccharide from fruit bodies of Pholiota nameko

Analysis of microbial community evolution, autolysis phenomena, and energy metabolism pathways in Pholiota nameko endophytes

Introduction

Pholiota nameko is a widely consumed edible fungus. This study focuses on two crucial developmental stages of Pholiota nameko, namely, mycelium and ascospores. The objectives of this research were to investigate changes in microbial diversity and community structure during the growth of Pholiota nameko and to analyze the adaptability of the dominant strains to their respective habitats through metabolic.

Methods

Specifically, we conducted second-generation sequencing of the 16S rRNA gene (Illumina) on samples obtained from these stages. In addition, we isolated and characterized endophytes present in Pholiota nameko, focusing on examining the impact of dominant endophyte genera on autolysis. We also conducted a metabolic pathway analysis.

Results and discussion

The results unveiled 578,414 valid sequences of Pholiota nameko endophytic fungi. At the phylum level, the dominant taxa were Basidiomycota, Ascomycota, Zoopagomycota, and Mucoromycota. At the genus level, the dominant taxa observed were Pholiota, Inocybe, Fusarium, and Hortiboletus. For endophytic bacteria, we obtained 458,475 valid sequences. The dominant phyla were Proteobacteria, TM6, Firmicutes, and Bacteroidetes, while the dominant genera were Edaphobacter, Xanthomonas, Burkholderia, and Pseudomonas. Moreover, we identified the isolated strains in Pholiota nameko using 16S rDNA, and most of them were found to belong to the genus Pseudomonas, with Pseudomonas putida being the most prevalent strain. The findings revealed that the Pseudomonas putida strain has the ability to slow down the breakdown of soluble proteins and partially suppress the metabolic processes that generate superoxide anion radicals in Pholiota nameko, thereby reducing autolysis. Additionally, our results demonstrated that molybdenum enzyme-mediated anaerobic oxidative phosphorylation reactions were the primary energy metabolism pathway in the Pseudomonas putida strain. This suggests that the molybdenum cofactor synthesis pathway might be the main mechanism through which Pholiota nameko adapts to its complex and diverse habitats.

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.

Pholiota nameko Polysaccharides Protect against Ultraviolet A-Induced Photoaging by Regulating Matrix Metalloproteinases in Human Dermal Fibroblasts

Ultraviolet-A (UVA) exposure is a major cause of skin aging and can induce oxidative damage and accelerate skin wrinkling. Many natural polysaccharides exhibit a UV protective effect. In research on Pholiota nameko polysaccharides (PNPs), a natural macromolecular polysaccharide (4.4–333.487 kDa), studies have shown that PNPs can significantly decrease elastase activity to protect against UVA-induced aging in Hs68 human dermal fibroblasts. Cellular experiments in the present study indicated that PNPs can protect against UVA-induced oxidative damage in Hs68 cells by inhibiting the production of reactive oxygen species. Furthermore, PNPs significantly attenuated UVA-induced cell aging by decreasing the protein expression of matrix metalloproteinase 1, 3, and 9. Pretreatment of Hs68 cells with PNP-40, PNP-60, and PNP-80 before UVA irradiation increased protein expression of tissue inhibitor metalloproteinase 1 by 41%, 42%, and 56% relative to untreated cells. In conclusion, this study demonstrates that PNPs are a natural resource with potentially beneficial effects in protecting against UVA-induced skin aging.

Triple-helix polysaccharides: Formation mechanisms and analytical methods

Triple helix conformation of polysaccharides is generally believed to be associated with their biological activities. However, the formation mechanisms and analytical methods for the triple helix polysaccharides, to our best knowledge, have not been systematically investigated. This article reviews specifically the literature on the formation and characterization of triple-helix polysaccharides. The formation mechanisms and related structural-conformation-bioactivity relationships are discussed; various analytical methods for characterizing triple-helix polysaccharides are summarized. This review devotes to a better understanding of the formation of polysaccharides based triple-helix structure and related analytical methods. These could provide some insights and inspirations for their applications in both food and pharmaceutical industries.

Extraction and structural analysis of Angelica sinensis polysaccharide with low molecular weight and its lipid-lowering effect on nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is one of the prevalent and typical chronic liver diseases. In this study, we extracted a novel Angelica sinensis polysaccharide (ASP) with low molecular weight (MW) of 3.2 kDa through optimized "one-step" purification process. The major monosaccharide components of ASP were mannose, rhamnose, glucuronic acid, galactose, arabinose, and xylose with weight ratio of 0.23:0.17:14.41:0.39:1.68:0.87, respectively. Herein, "small" ASP could serve as an effective therapeutic option for NAFLD both in free fatty acid-induced L02 models and in high-fat diet-induced mice models. Results revealed that low MW ASP dose-dependently decreased TG, TC in vitro and TG, TC, ALT, HDL-C, and LDL-C in vivo. Oil Red O-positive area and Nile red fluorescence intensity decreased in ASP treatment groups both in vitro and in vivo which suggested ASP could reduce lipid accumulation and fatty regeneration. Hematoxylin-eosin staining results shown a decrease in hepatocytes ballooning indicating that ASP could ameliorate liver lipid degeneration. Briefly, a novel polysaccharide with low MW was successfully obtained which can prospectively act as NAFLD therapy.

Two new sesquiterpenes from cultures of the higher fungus Pholiota nameko

Two new sesquiterpenes (1-2), along with one known sesquiterpene (3), were isolated from cultures of the higher fungus Pholiota nameko. The structures of new compounds were elucidated by extensive spectroscopic methods. The known compound was identified by comparing its spectroscopic data with those reported in the literature. All compounds were evaluated for their cytotoxicities against five human cancer cell lines.