|
Everyone suffers from the damage by the reactive oxygen species generated in the process of respiration and/or metabolism of exogenous materials. Free radical oxidation can also be a major problem in the storage of fatty food. Therefore, a lot of effort has been made around the world to utilize naturally occuring substances as health promoting foods as well as antioxidants. The intrinsic chemical property of these radical quenching substances, however, grants a possible role in the propagation of the radical depending on the microenvironment. In the present study, selected plant extracts with reported antioxidative activity against lipid peroxidation were screened in vitro for the pro-oxidant activity. The ultimate purpose of the present report was to establish a method that can be used in the search for biologically safe antioxidants. Most of the eighteen plant extracts, aqueous and ethanol, showed a powerful protective effect on lipid peroxidation and hydroxy radical scavenging activity in aqueous environment. Several samples, including aqueous extract of perssimon leaf and ethanolic extract of green tea, induced DNA damage and deoxyribose breakdown in the test system, suggesting the presence of reducing agents powerful enough to convert ferric ion to the more destructive ferrous form. Aqueous extracts of pleurotus and codonopsis showed oxidative mutagenesis in bacterial assay using Salmonella typhimurium TA 102. Among the four test methods, the deoxyribose assay showed the best correlation with other assays, suggesting its use as a rapid screening method.
|