Comparison of antioxidant activity and extraction techniques for commercially and laboratory prepared extracts from six mushroom species

Mushrooms are a potent source of dietary antioxidants and are often marketed for their capability of decreasing oxidative stress and preventing diseases. To date, however, little research has been done on the antioxidant activity of commercially available mushroom extractions, or their stability over time. Herein, the antioxidant capacity of six commercially available mushroom tinctures (hydro-alcoholic extracts of chaga, maitake, shiitake, reishi, lion's mane, and turkey tail) were evaluated using a panel of five antioxidant assays: Oxygen Radical Absorbance Capacity (ORAC), Nanoceria Reducing Antioxidant Capacity (NanoCerac), DPPH radical scavenging, Total Phenolic Content (TPC), and Ferric Reducing Antioxidant Power (FRAP). Commercial samples were compared to our own laboratory preparations of the same species, in a preliminary assessment of extraction technique and antioxidant stability. Mushroom extracts exhibited different antioxidant capacities depending on species and extraction method (e.g., 0.023 to 0.63 μmol TE/mg for commercial ORAC vs. 0.05 to 1.8 μmol TE/mg for laboratory ORAC for all species). In all cases, laboratory extracts exhibited considerably higher antioxidant activities than commercial extracts. In both extract types, chaga and maitake consistently demonstrated higher antioxidant activity than the other mushrooms. Preliminary antioxidant stability testing of our samples revealed stable ORAC values for one month at room temperature, followed by a 48% decrease after 4 months. Our results provide important insights regarding the effects of extraction techniques and storage conditions, on the antioxidant activity in mushroom extracts, particularly those made and sold commercially.