Activity-guided isolation and structural identification of immunomodulating substances from Pleurotus eryngii...

A two-step extraction process was used to investigate the bioactive substances from the byproducts of the fungus Pleurotus eryngii. Methanol extraction followed by extraction using different polar solvents coupled with silica column chromatography was carried out to separate the bioactive components. The immunomodulating activity of the extracts was investigated using Ana-1 mouse macrophage cells. At 25μg/mL, the butyl alcohol extract showed the highest enhancement of Ana-1 cell proliferative activity and secretion of cytokines. Using silica-gel column chromatography, the butyl alcohol extract was purified to seven elution fractions. Fr. 2 showed the highest promotion of Ana-1 macrophage cell proliferation and TNF-α, IL-6 secretion. HPLC-QTOF-MS/MS was used to determine the structure of the active substance in Fr. 2. Adenosine was identified as the primary active component in Fr. 2 with a chemical formula of C₁₀H₁₃N₅O₄. Adenosine may be useful as a natural immunostimulatory agent and anti-tumor agent.