Activity, thermostability and isozymes of superoxide dismutase in 17 edible mushrooms

Activity, thermostability and isozymes of superoxide dismutase (SOD) of 17 edible mushrooms from China were investigated in this study. The results indicated that most of these mushrooms have high SOD activities, especially Pleurotus citrinopileatus, Agaricus bisporus, Pleurotus ostreatus, Volvariella volvacea and Agrocybe aegerita, which contained SOD activities of higher than 1000 units per gram fresh weight (U/g FW). The cap of Coprinus comatus and P. citrinopileatus contain the highest SOD specific activities. Usually the SOD activity of the cap was higher than in the stipe. SODs of edible mushrooms show high thermal stability, with 40–95% activity still present after treatment at 90 °C for 10 min. Both manganese superoxide dismutase (MnSOD) and iron superoxide dismutase (FeSOD) were identified. The main isozymes were MnSODs and ranged from 0.8 to >10 μg/g FW in whole mushrooms, from 0.1 to 6.2 μg/g FW in cap, and from 0.06 to 3.5 μg/g FW in stipe. This was much higher than the concentration of FeSODs at 31–489 ng/g FW. MnSOD content of the cap was higher than that of the stipe and the highest level of MnSODs occurring in A. bisporus and the cap and stipe of A. aegerita.