Antioxidant activities and phenolic constituents of Cephalotaxus oliveri Mast. aerial parts

The antioxidant activity and the responsible chemical constituents in Cephalotaxus oliveri Mast. aerial parts were analyzed in the present study. The DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azinobis(3-ethyl-benzothiazoline-6-sulfonic acid)), reducing power and total phenolic content assays indicated that the methanol extract of the aerial parts was the most potent radical-scavenger and reducing agent and had the highest content of phenolics among the tested extracts. The high positive linear correlations implied that the four assays had a similar capacity to predict the antioxidant potential of the aerial parts and that the present phenolic compounds contribute significantly to the DPPH and ABTS radical scavenging activities and to the reducing power of the extracts. The plant also displayed considerable superoxide anion radical scavenging activity. LC-MS/MS and GC-MS analyses resulted in the identification of 22 compounds in the methanol extract, of which 15 were phenolic compounds. The total amount of the phenolic compounds in the methanol extract determined by the HPLC method was more than 5.62 mg g(-1) dry weight. The considerable antioxidant potential and a high content of phenolic antioxidants suggest that C. oliveri aerial parts are a potential source of natural antioxidants.