Antioxidant and antimicrobial activity of mushrooms Daedalea quercina and Fistulina hepatica

Daedalea quercina and Fistulina hepatica are lignicolous mushrooms, which belong to medicinally important mushrooms. They contribute to the breakdown of lignocellulosic substrates, using N, P, C, K, Fe, Mg, Zn, Cu, compounds necessary for their growth and development. The objectives of this study were: 1) to determine the antimicrobial ability of hot water and hot alkali extracts, obtained from the fruiting bodies of Daedalea quercina and Fistulina hepatica, towards pathogenic bacteria Salmonella Enteritidis ATCC 13076 and Listeria monocytogenes ATCC 19115, using a microdilution method; 2) to assess their antioxidant ability through the possibility of neutralizing free DPPH radicals and the ability to reduce copper ions. The minimum inhibitory concentration (MIC) of both examined extracts of D. quercina was 5 mg/mL against S. Enteritidis, while a bit higher concentrations of hot water (MIC-20 mg/mL) and hot alkali (MIC-10 mg/mL) extract of this mushroom where needed for inhibition of L. monocytogenes. The minimum bactericidal concentration (MBC) was not reached at the tested concentrations of the extracts. The growth inhibition of both bacteria was achieved by hot water (MIC-20 mg/mL) and hot alkali (MIC-10 mg/mL) extracts of F. hepatica; the microbicidal effect towards L. monocytogenes was obtained by the hot alkali extract of this mushroom (MBC-20 mg/mL). The antioxidative activity assays were based on their ability to neutralize 1,1diphenyl-2-picrylhydrazil radical (DPPH) and reduction of copper ions. Hot water extract of D. quercina has an extremely pronounced ability to neutralize DPPH radicals (EC50 <0.1 mg/mL), while the water extract of F. hepatica also exhibited this capacity (EC50 = 1.96 mg / mL). Alkali extracts of both mushrooms showed a lower ability to scavenge DPPH radicals (EC50>20 mg/mL). All the extracts exhibited poor copper ion reduction (EC50>20 mg/mL) at the tested concentrations. The extracts examined in this investigation possess antimicrobial and antioxidant properties but further research is needed in order to apply them as a potential food additives or pharmaceutical agents.