Phenolic compounds are commonly found in plants, both edible and inedible. They have been reported to have various biological effects such as their well known ability to scavenge free radicals [9], antimutagen [10], and anticarcinogen [11]. Recent studies showed that many dietary polyphenolic constituents derived from plants are more effective antioxidants in vitro than vitamins E or C, and thus might contribute significantly to the protective effects in vivo [12]. Flavonoids as one of the most diverse and widespread group of natural compounds, are likely to be the most important natural phenolics with free radical scavenging capacity [13]. These compounds posses a broad spectrum of biological activities i.e., inhibiting lipid oxidation by scavenging free radicals or by other mechanisms such as singlet oxygen quenching,metal chelation, and lipoxygenase inhibition [14].