However, interactive actions among components in these multi-herbs and the involved mechanism remain poorly understood. Phenolic substances and flavonoids are increasingly recognized as the major bioactive components contributing to the antioxidant potency of many herbs. For example, Fattahi et al. found that the significant antioxidant activity of Dracocephalum kotschyi was correlated with the flavonoid content. Misbah et al. reported that the antioxidant activities of the fruits of F. deltoidea might be asserted by the phenolic content. The SUN B8155 combination of Vernonia amygdalina and Azadirachta indica showed a positive synergism in antioxidant action, due to a boost in the flavonoid content of the extracts. The mechanisms of antioxidant activity of phenolics and flavonoids can be characterized not only by directly scavenging or quenching free radicals, but also by inducing various intracellular antioxidant enzymes. Nagata et al. revealed that cytoprotective effect of quercetin and catechin against H2O2 cytotoxicity in rat hepatocytes BL-9 was related to the activation of GPx. Leung et al. provided evidence that luteolin-induced human lung carcinoma CH27 cell apoptosis was accompanied by activation of SOD and CAT. Furthermore, some antioxidant effects may be a reset of a combination of radical scavenging and the interaction with enzyme functions. For instance, ethyl acetate-extracted fraction of Ficus glomerata, rich in phenolic compounds, possessed high potency to scavenge reactive oxygen species/free radicals and restore the levels of GSH, SOD and CAT. However, these studies mainly focused on the cytoprotective or antioxidant effects of the phenolic compound, flavonoid or extracts from single herb, and limited information is available regarding interactive actions among them. Atractylodes PF-06737007 macrocephala and Paeonia lactiflora are very popular medicinal herbs in some Asian countries, which are commonly used in combination as dietary supplements. Our preliminary results indicated that AME and PL were able to result in a significant synergy in scavenging the DPPH radical, hydroxyl radical and superoxide radical anions.