In vitro antioxidant activity of olive leaf extract (Olea europaea L.) and its protective effect on oxidative damage in human erythrocytes

Patricia Goldschmidt Lins; Silvana Marina Piccoli Pugine; Antonio Márcio Scatolini; Mariza Pires de Melo

doi:10.1016/j.heliyon.2018.e00805

In vitro antioxidant activity of olive leaf extract (Olea europaea L.) and its protective effect on oxidative damage in human erythrocytes

Heliyon. 2018 Sep 20;4(9):e00805. doi: 10.1016/j.heliyon.2018.e00805. eCollection 2018 Sep.

Authors

Patricia Goldschmidt Lins¹, Silvana Marina Piccoli Pugine¹, Antonio Márcio Scatolini¹, Mariza Pires de Melo¹

Affiliation

¹ Department of Basic Science, Faculty of Animal Science and Food Engineering (FZEA), University of São Paulo, Pirassununga, SP, Brazil.

Abstract

Aims: 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.

Main methods: 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 ( ${O_{2}}^{\cdot -}$ ), 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.

Key findings: 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 ${O_{2}}^{\cdot -}$ (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.

Significance: OLE is an important source of natural antioxidants; it has effective antioxidant activity against different reactive species and protects human erythrocytes against oxidative damage.

Keywords: Food science; Food technology; Nutrition.