Mycochemical study of the mushroom Tricholoma populinum

Tricholoma populinum J.E. Lange also known as cottonwood mushroom is a basidiomycetes species, which belongs to the fairly large genus of Tricholoma. It is widespread in Europe and North America, growing on sandy soil under cottonwood trees near a source of water. T. populinum is an edible mushroom largely consumed by Salish Indian peoples of British Columbia and also by locals of Sicily. Previous chemical investigations have revealed the presence of ergosterol peroxide, which showed immunosuppressive activity. Now we report on the isolation and structure determination of adenosine type compounds, besides the previously known sterol constituents.

Sporocarps of T. populinum were collected in the vicinity of Szeged, southern part of Hungary. The fresh mushroom material was freeze dried to eliminate water. The dried mushroom (310 g) was extracted with methanol at room temperature. The concentrated methanol extract was subjected to solvent-solvent partition first between n-hexane and then chloroform. The chloroform extract was fractionated by repeated rotational planar chromatography. The final chromatographic step was carried out using reversed phase HPLC to obtain pure compounds. The structure elucidation was performed by extensive spectroscopic analyses, including NMR and MS measurements. Based on spectral data the isolated compounds were identified as adenosine, and epimers of 5'-deoxy-5'-methylsulfinyladenosine, which are considered rare fungal metabolites, found previously only in Ganoderma lucidum. Pharmacological assays are planned to determine the biological activity of these purine base compounds.