Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/22/2003
Publication Date: 10/22/2003
Citation: Lee, K-G., Shibamoto, T., Takeoka, G.R., Lee, S-E., Kim, J-H., Park, B-S. 2003. Inhibitory effects of plant-derived flavonoids and phenolic acids on malonaldehyde formation from ethyl arachidonate. Journal of Agricultural and Food Chemistry. Vol 51:7203-7207. Interpretive Summary: There is a strong need to find alternative natural antioxidants since some synthetic ones have been reported to be toxic to humans. Natural antioxidants including flavonoids have been shown not only to prevent oxidative deterioration in foods but also to inhibit oxidative damage caused by lipid peroxidation. It is thought that many diseases such as cancer, atherosclerosis, aging, leukemia, rheumatoid arthritis, liver diseases, and diabetes, are mediated by oxidative processes. In the present study, flavonoids and phenolic acids derived from plants were evaluated for antioxidant activity using a lipid peroxidation system. Although there is data available on the importance of antioxidants in conferring stability towards or protection from oxidation, the correlation between antioxidant activity and chemical structure is far from clear. The aim of this study was to elucidate the relationship between antioxidant activity and chemical structure of flavonoids and phenolic acids. This study may help to identify the active ingredients in beverages, fruits, vegetables and grains that protect against free radical damage, LDL oxidation, and cancer. This may provide useful information from the point of view of identifying appropriate foods that are rich in these protective compounds for the development of safe food products and additives with proper antioxidant properties.
Technical Abstract: The antioxidant activities of naturally occurring plant compounds were measured in a lipid peroxidation system consisting of ethyl arachidonate and Fenton's reagent. Inhibitory effects of 24 plant-derived flavonoids and 5 phenolic acids on malonaldehyde (MA) formation from ethyl arachidonate were examined using gas chromatography (GC) with a nitrogen-phosphorus detector (NPD). Luteolin, which showed the strongest antioxidant activity, inhibited MA formation by 94% and 97% at the levels of 0.5 and 1.0 mM, respectively. The antioxidant activities of the flavones and flavonols decreased in the following order: luteolin > rhamnetin > fisetin > kaempferol > morin > quercetin. Among the flavanones tested, hesperitin, taxifolin, and naringenin exhibited appreciable antioxidant activities (61-84%) at the 1.0 mM level. The inhibitory effect of epigallocatechin gallate (82.5% at the 1.0 mM level) was the strongest among the flavan-3-ols tested. Ferulic acid had the most potent antioxidant activity (74.6% at the 1.0 mM level) of the phenolic acids tested.