Differences in antioxidant activities of outdoor- and indoor-cultivated Agaricus brasiliensis, and protective effects against carbon tetrachloride-induced acute hepatic injury in mice

Background: Agaricus brasiliensis (A. brasiliensis) is a medicinal mushroom that exerts various pharmacological actions. We previously demonstrated that different cultivation conditions altered the activity of the polyphenol-related enzymes from this mushroom. However, the influence of cultivation conditions on the antioxidant activity of the fruiting bodies remains unclear. Therefore, in this study we compared the antioxidative effects of fruiting bodies of A. brasiliensis cultivated outdoors and indoors. In addition, we assessed whether different cultivation methods affected the hepatoprotective effects against CCl4-induced liver injury. Methods: We assessed the antioxidative effects of mushrooms cultivated in open-air or indoors using the DPPH radical-scavenging assay. Furthermore, we prepared experimental feeds containing outdoor-or indoor-cultivated A. brasiliensis. Acute liver injury was induced by CCl4 injection in mice that consumed feed containing outdoor- or indoor-cultivated A. brasiliensis. The hepatoprotective effects of these mushrooms were then evaluated by monitoring the reduction in the circulating levels of alanine aminotransferase, aspartate aminotransferase, and lactate dehydrogenase. The significance of the differences between the means was assessed using Student's t-test. Finally, histopathological analysis of liver was performed. Results: In the DPPH assay, the antioxidant activity of outdoor-cultivated A. brasiliensis was higher than that of indoor-cultivated mushroom. Moreover, in the mouse model of CCl4-induced hepatitis, the oral administration of outdoor-cultivated A. brasiliensis reduced liver damage significantly, but indoor-cultivated mushrooms failed to inhibit hepatitis. The hepatoprotective effects of outdoor-cultivated A. brasiliensis were observed even when ingestion commenced only 1 day before CCl4 injection, and these effects were not affected by excessive heat treatment. Conclusions: Outdoor cultivation significantly enhanced the antioxidative activity of A. brasiliensis fruiting bodies. In addition, outdoor-cultivated A. brasiliensis was more effective at protecting against CCl4-induced liver injury in mice than mushrooms grown in a greenhouse.