Recently, the formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been implicated in the oxidative deterioration of food products as well as in the pathogenesis of several human diseases such atherosclerosis, diabetes mellitus, chronic inflammation, neurodegenerative disorders and certain types of cancer. Plant secondary metabolites mainly phenolics and flavonoids are commonly found in various fruits, vegetables and herbs. The plant-derived antioxidants may use as therapeutics for before mentioned diseases. They play this role through acting as reducing agents by donating hydrogen, acting as chelators, quenching singlet oxygen and scavenging free radicals. In the present study, four extracts of Platycladus orientalis (L.) Franco leaves by maceration in water, methanol, ethanol and ethyl acetate, were prepared and the antioxidant activities of the extracts have been investigated by DPPH method, H2O2 scavenging activity and reducing power assays. The total phenol and flavonoid contents of these extracts were determined and compared with their antioxidant potential. The results showed that antioxidant effect of these extracts is increased in the following order: water < ethyl-acetate < ethanol< methanol extract. Among the extracts, the methanol extract showed as strong extract in both DPPH radical (IC50: 11.45 μg/ml) and H2O2 (IC50: 49.9 μg/ml) scavenging activity assays. The ethanol extract was shown a highest reductive potential in comparison with other extracts. There was positive and significant correlation between antioxidant properties and total phenol and flavonoid content of P. orientalis. It was concluded that the extracts of P. orientalis can use as a source of natural antioxidants in preventation of cellular oxidation.
