ABSTRACT
Gymnopilus consists of a widely distributed genus of basidiomycetes, especially in tropical regions of the world, such as Japan, Australia, Paraguay, and Brazil. This genus biosynthesizes interesting bioactive compounds, such as sesquiterpenoids, oligoisoprenoids, styrylpyrones, and lectins. In the present study, the aqueous extract of the basidiomata of Gymnopilus imperialis (Basidiomycota, Agaricomycetes, Agaricales, Hymenogastraceae) was obtained by using the accelerated solvent extraction (ASE) technique, followed by the precipitation of polysaccharide fraction with ethanol. Further purification by freeze-thawing processes, Fehling solution precipitation, and membrane dialysis with different pore sizes yield three main polysaccharide fractions (Gi-MRSW, Gi-PFME, and Gi-SFME). According to monosaccharide composition and 13C-NMR data, the Gi-MRSW and Gi-SFME fractions showed to be composed mainly of ß-glucans and Gi-PFME by a heterogalactan. Moreover, the immunomodulatory potential of Gi-MRSW was evaluated using RAW 264.7 murine macrophage as a study model. The nitric oxide production was significantly increased in treated samples, and the expression of inducible nitric oxide synthase (iNOS) showed that the fraction Gi-MRSW from G. imperialis induces the M1 polarization phenotype.
ABSTRACT
Gymnopilus consists in a widely distributed genus of mushroom-forming fungi, especially in tropical regions of the world. Literature on Gymnopilus representatives reports the presence of oligoisoprenoids, and styrylpyrones. Considering the large number of secondary metabolites that basidiomycetes might contain, dereplication tools such as GNPS (Global Natural Products Social Molecular Networking), has become important in prospecting metabolites, saving time and work on isolation and characterization of natural products. Thus, this work identified the wild mushroom Gymnopilus imperialis and dereplicated their extracts with the aid of GNPS to annotate oligoisoprenoids. It was possible to annotate 24 oligoisoprenoids from methanol, dichloromethaneand ethyl acetate extracts of G. imperialis, 4 of them from GNPS spectral library match, and 20 from prediction based on molecular network. Moreover HRMS-ESI-(+) dereplication of the acetate extract annotated bisnoryangonin and hispidin. To the best of our knowledge, this is the first report on the annotation of a series of gymnopilins analogues based on GNPS molecular network. Our findings suggest that GNPS might be an effective, rapid, and open-source device to identify compounds and predict analogues.
