Structure identification, antitumor activity and mechanisms of a novel polysaccharide from Ramaria flaccida (Fr.) Quél

Abstract

It is an important aspect of current cancer research to search for effective and low-toxicity anticancer drugs and adjuvants. Polysaccharides, as immunomodulators, can improve the immune function of the body, kill tumor cells directly and prevent tumor development by increasing the resistance of the body to carcinogenic factors. The aim of the present study was to identify natural polysaccharide compounds with novel structure and antitumor activity via the separation and analysis of polysaccharide components from Ramaria flaccida (Fr.) Quél. (RF-1). In the present study, high-performance gel permeation chromatography, gas chromatography-mass spectrometry and nuclear magnetic resonance were used to identify the structure of polysaccharides from RF-1. Subsequently, the antitumor activity and mechanism of RF-1 were studied by establishing an in vivo S180 tumor model, and by using Illumina sequencing technology and enzyme-linked immunosorbent assay (ELISA). The present results revealed that the average molecular weight of RF-1 was 17,093 Da and that RF-1 was composed of the monosaccharides glucose and galactose, with a 2:1 ratio. The main chain of RF-1 consisted of (1→6, 2)-α-D-galactopyranose and (1→6, 4)- α-D-glucopyranose. One of the branched chains was linked to 4-O of the main glucose chain by (1→6)-α-D-glucopyranose and next linked by one (→4)-β-D-glucopyranose. The other two branched chains were both linked to 2-O of the main glucose chain by one (→4)-β-D-glucopyranose. In addition, RF-1 inhibited the growth of S180 tumors in vivo . When the concentration of RF-1 was 20 mg/kg, the inhibition rate of S180 tumors in mice was 48.4%. Compared with the blank control group, 1,971 differentially expressed genes were identified, of which 818 were upregulated and 1,153 were downregulated in the RF-1 group. A Gene Ontology enrichment analysis generated 47,091 assignments to biological processes, 5,250 assignments to cellular components, and 6,466 assignments to molecular functions. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that the Wnt and MAPK signaling pathways were significantly enriched. The number of differentially annotated genes in these two pathways was 19 and 33, respectively. Additionally, ELISA results revealed that the protein levels of interleukin (IL)-1β, IL-6, vascular endothelial growth factor (VEGF) and VEGF receptor in the RF-1 group were significantly downregulated compared with the S180 blank control group (P<0.01).

A preliminary study on preparation, characterization, and prebiotic activity of a polysaccharide from the edible mushroom Ramaria flava

“…The relative molar percent were 40.61%, 26.97%, 17.72%, 7.78%, 6.31%, 0.11%, 0.06% and 0.44% (Table 1). This was consistent with previous literature which suggested that Ramaria polysaccharides mainly consist of glucose, galactose, and mannose (Bhanja et al, 2013; Dong et al, 2020; Li, 2017). Beyond that, proteins and sulfates separately took up 8.18% and 4.12% of DRFP mass.…”

“…According to the calibration curve connecting the Mw and elution volume of Dextran T‐series, the Mw of DRFP was calculated to be 101.68 kDa. The Mw was lower than immunoenhancing glucan from R. botrytis (Bhanja et al, 2013), and much higher than the antitumor polysaccharide from R. flaccida and antioxidant polysaccharides from R. botrytis (Dong et al, 2020; Li, 2017). This difference might be explained by differences in the strains or growth conditions.…”

“…It could be speculated that monosaccharide residues of DRFP were mostly in the form of β‐pyranose configuration, different from R. flaccida (Fr.) Quél polysaccharides (Dong et al, 2020).…”

“…Furthermore, when signals were below δ 5.0 ppm, they were in the form of β-pyranose unit, while others were α-pyranose unit (Liu et al, 2020). In Figure 2d, Quél polysaccharides (Dong et al, 2020).…”

The first two mitochondrial genomes for the genus Ramaria reveal mitochondrial genome evolution of Ramaria and phylogeny of Basidiomycota

“…Some Ramaria fruiting bodies are considered to be poisonous, including Ramaria flavo-brunnescens and Ramaria rufescens (Huang et al 2009 ; Perez-Moreno and Ferrera-Cerrato 1995 ; Scheid et al 2022 ), while other Ramaria species are edible, such as Ramaria botrytis , Ramaria madagascariensis , Ramaria largentii , Ramaria flava , and Ramaria formosa (Aprotosoaie et al 2017 ; Khaund and Joshi 2014 ; Liu et al 2014 , 2015 ). Polysaccharide, sesquiterpenes, and glucan extracted from the basidiocarps of Ramaria exhibited antioxidant, antigenotoxic, antitumor, antimicrobial, and immunoenhancing activities (Barros et al 2008 ; Bhanja et al 2013 ; Centko et al 2012 ; Dong et al 2020 ; Fu et al 2022 ; Li 2017 ; Liu et al 2013 ; Zou et al 2021 ). All in all, the accurate identification and classification of Ramaria species is very important for the development and utilization of Ramaria species.…”