Analogy in selenium enrichment and selenium speciation between selenized yeast Saccharomyces cerevisiae and Hericium erinaceus (lion's mane mushroom)
Résumé
Human selenium supplementation is vastly dominated by selenized yeasts based products not only due to regulation issues but due to the fact that yeasts convert inorganic selenium into organic forms up to 2000 μg g-1 through a well characterized selenium metabolism. Though both yeasts and the higher mushroom Agaricomycetes belong to the kingdom of fungi, their selenometabolic pathways are different. Agaricomycetes, the most widely researched higher fungi tend to store the excess of selenium in inorganic forms. A sample of Hericium erinaceus (lion's mane mushroom), also belonging to Agaricomycetes, was examined in our study after moderate selenium enrichment from inorganic selenium source. Enzymatic digestion and ion-pairing chromatography coupled to ICP-MS revealed that nearly 50% of the selenium was in organic forms: selenomethionine and Se-methylselenocysteine. To explore the background of this, directed orthogonal chromatographic purification was executed in search for Se-adenosyl compounds, typical for yeast metabolism. After HPLC-ESI-QTOFMS analyses three Se-adenosyl-compounds were identified: Se-methyl-5-selenoadenosine, Se-methyl-5-selenoadenosine-Se-oxide and the previously unreported Se-dimethyl-5-selenonium-adenosine. Two of these species have been linked only to the selenium metabolism of yeasts. The high selenomethionine content and the presence of Se-adenosyl compounds in Hericium erinaceus open the possibility for a functional food alternative to selenized yeast based dietary supplements. © 2015 Elsevier Ltd.