ABSTRACT
This study is reporting the in vitro antioxidant activity of the fruiting body of the edible mushroom Pleurotuspulmonarius (Fr.) Quel. The fruiting body of the edible mushroom was defatted with n-hexane and furtherextracted by successive maceration in dichloromethane (DCM) and 80% aqueous ethanol (AQE) to obtainthe DCM and AQE extracts, respectively. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavengingand iron chelating assays were used for antioxidant evaluation in vitro with ascorbic acid as the referencestandard for comparison. Isolation and structural elucidation of the steroid were done using chromatographicand spectroscopic techniques, respectively. The trend for the DPPH radical scavenging activity: ascorbic acid[inhibition concentration (IC)50 = 0.012 mg/ml] > AQE (IC50 = 0.525 mg/ml) > DCM (IC50 = 1.820 mg/ml)and for the iron chelating activity: ascorbic acid (IC50 = 0.214 mg/ml) > AQE (IC50 = 1.318 mg/ml) > DCM(IC50 = 7.586 mg/ml) were observed. From the DCM was isolated a pure compound 1 elucidated to be theknown steroidal isoprenoid: ergosta-5, 7, 22-trien-3β-ol. This study aside reporting the isolation of the knowncompound 1 from this species of Pleurotus, has also shown that compound 1 has a significant iron chelatingactivity at 0.001 mg/ml of 77.06% compared to 4.56% at same concentration for DPPH scavenging activity.