IndexChelating effect of metalsReducing powerAntioxidant activity in linoleic acid emulsionTotal polyphenolic compoundsIn cells, free radicals are continuously produced as by-products of metabolism or deliberately as in phagocytes (Cheeseman and Slater 1993). The DPPH radical scavenging model is particularly useful for evaluating chain-breaking activity in the propagation phase of lipid (and protein) oxidation (Manzocco et al. 1998). The effect of antioxidants on the scavenging of DPPH radicals was thought to be a result of their ability to donate hydrogen (Gulcin et al. 2004). Figure 1 shows the dose-response curves for the DPPH radical scavenging activities of five nanoemulsions. The DPPH scavenging activity of aqueous E. ulmoides extracts increases with increasing amount of extract. The leaf extract showed significantly (p < 0.05) stronger DPPH scavenging activity ((i.e. a [IC.sub.50] less than 0.274 [+ or -] 0.010 mg/mL) compared to other extracts, and its polyphenolic content (112.79 [+ or -] 7.18 mg/g) was significantly higher than other extracts. Although the polyphenolic content of the male flower extract was not significantly different from that of the bark , its DPPH scavenging effect (I[C.sub.50] - 0.596 [+ or -] 0.003 mg/mL) was significantly stronger than that of the cortex (I[C.sub.50] - 0.955 [+ or -] 0.037 mg/mL The order of DPPH scavenging activity was ascorbic). acid > BHT > leaf > male flower > bark > fruit. Say no to plagiarism Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get Original Essay Chelating Effect of Metals Chelating ability of metals is considered one of the chelating properties of metals. mechanisms of antioxidant activity (Diplock (1996, Yildirim et al. 2001), since it reduces the concentration of the catalyzing transition metal in lipid peroxidation (Hsu et al. 2003). It has been reported that chelating agents, which complex with metallic bonds through [sigma] bonds, they are effective as secondary antioxidants because they reduce the redox potential, thus stabilizing the oxidized form of the metal ion (Gordon 1990). E. ulmoides extract the formation of the complex is disrupted resulting in the red color of the complex decreasing. As shown in Table 1, the leaf extract and ascorbic acid show a significantly higher metal chelating effect than others. extracts and BHT. At the concentration of 1 mg/ml, their metal chelating effects were 69.73 [+ or -] 2.12% and 67.70 [+ or -] 2.43% respectively fruit and bark extracts have also demonstrated a certain ability to chelate metal ions. However, BHT and male flower extract show very poor (negligible) iron chelating capacity. The decreasing order of metal chelating effect was leaf > ascorbic acid > fruit > bark > male flower and BHT. Reducing power The reducing capacity of a compound can serve as an indicator of its potential antioxidant activity (Meir et al. 1995). In the reducing power test, the antioxidant activity of the samples was measured based on their ability to reduce the [Fe.sup.3+]/ferriccianide complex forming ferrous products. Figure 2 shows the reductive power of E. ulmoides with respect to BHT and ascorbic acid. Similar to the antioxidant activity, the reducing power of E. ulmoides increases with increasing dosage. All E. ulmoides extracts showed some reducing power. However, the reducing powers of the.