In vitro antioxidant activity of olive leaf extract (Olea europaea L.) and its protective effect on oxidative damage in human erythrocytes
2018
Lins, Patricia Goldschmidt | Marina Piccoli Pugine, Silvana | Scatolini, Antonio Márcio | de Melo, Mariza Pires
This study aimed to evaluate in vitro antioxidant capacity of olive leaf extract (OLE), Olea europaea L., and its protective effect on peroxyl radical-induced oxidative damage in human erythrocytes. The OLE was evaluated by the following assays: i) total phenolic and flavonoid content; ii) oleuropein content; iii) Ferric reducing antioxidant power (FRAP); iv) antioxidant activity against ABTS⁺, DPPH and reactive oxygen and nitrogen species: superoxide anion (O2·−), hypochlorous acid (HOCl) and nitric oxide (NO) and v) protective effect on peroxyl radical-induced oxidative damages in human erythrocytes as hemolysis, thiobarbituric acid reactive substances (TBARS) formation and oxyhemoglobin oxidation. Total phenolic and flavonoid contents were 131.7 ± 9.4 mg gallic acid equivalents/g dry weight (dw) and 19.4 ± 1.3 mg quercetin equivalents/g dw, respectively. Oleuropein content was 25.5 ± 5.2 mg/g dw. FRAP analysis was 281.8 ± 22.8 mg trolox equivalent/g dw and OLE inhibited ABTS⁺ (50% effective concentration (EC₅₀) = 16.1 ± 1.2 μg/mL) and DPPH (EC₅₀ = 13.8 ± 0.8 μg/mL). The extract demonstrated effective ability to scavenge O2·− (EC₅₀ = 52.6 ± 2.1 μg/mL), NO (EC₅₀ = 48.4 ± 6.8 μg/mL) and HOCl (EC₅₀ = 714.1 ± 31.4 μg/mL). The extract inhibited peroxyl radical-induced hemolysis (EC₅₀ = 11.5 ± 1.5 μg/mL), TBARS formation (EC₅₀ = 38.0 ± 11.7 μg/mL) and hemoglobin oxidation (EC₅₀ = 186.3 ± 29.7 μg/mL) in erythrocytes. OLE is an important source of natural antioxidants; it has effective antioxidant activity against different reactive species and protects human erythrocytes against oxidative damage.
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