Applicability of a Voltammetric Assay Based on the Electroreduction of Oxygen to Evaluate the Antioxidant Capacity of Pequi (Caryocar brasiliense Camb.) Pulp

Abstract

This study aimed to use a differential pulse voltammetric (DPV) assay, based on the electroreduction of oxygen, to evaluate the antioxidant capacity of pequi pulp. The results were expressed in coefficient of antioxidant capacity (K), at different pH values and in trolox equivalent antioxidant capacity (TEAC), and were compared to the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) spectrophotometric assays. The principal component analysis showed higher K for pequi pulp extract and pH tending to 7.15. The antioxidant capacity was related to the presence of gallic acid in its composition. Regarding the TEAC value, the best result was obtained by the DPV test (53.43 ± 5.14 µmol trolox g -1 pulp). The pequi pulp showed antioxidant capacity, compared to the standard antioxidant compounds evaluated. It was concluded that the voltammetric protocol was efficient to assess the total antioxidant capacity of pequi pulp and can be an alternative to conventional spectrophotometric assays, for the analysis of food matrices.

Efeito dos extratos de jabuticaba e pequi na expressão gênica de enzimas antioxidantes em células musculares C2C12 de camundongos

“…Prior to the determination of plant extracts cytotoxicity, the phenolic compounds content was determined and the antioxidant capacity was evaluated (ABTS and DPPH assays), according to the methodology described by Re et al (1999) and Brand-Williams, Cuvelier and Berset (1995), respectively, with modifications described by Pinheiro et al (2018). Results were expressed as trolox equivalent (µmol trolox mL -1 extract).…”

Influence of the extraction process on the antioxidant capacity of pequi pulp extracts

“…Total antioxidant capacity of the pequi pulp extracts was evaluated based on oxygen electroreduction in 0.1 mol L -1 Britton-Robinson buffer support electrolyte, applying the voltammetric differential pulse technique (DPV), according to Pinheiro et al (2018). The antioxidant capacity was expressed by the coefficient of antioxidant capacity (K) at pH 2.20; 4.05; 7.15 and 10.05, and by trolox equivalent (μmol trolox mL -1 pequi extract), based on the intensity values of the cathodic oxygen current obtained at pH 7.15.…”

“…The spectrophotometric methods used to evaluate the antioxidant capacity were based on the DPPH and ABTS assays, described by Brand-Williams, Cuvelier and Berset (1995) and Re et al (1999), respectively, with modifications described by Pinheiro et al (2018).…”

“…Comparing average antioxidant capacity between the assays (Figure 6), it can be seen that higher antioxidant action was obtained by the DPV assay for all extracts (AM: 11.13 ± 1.07 μmol trolox mL -1 extract; ALC: 9.61 ± 0.10 μmol trolox mL -1 extract and AQ: 9.64 ± 0.41 μmol trolox mL -1 extract). According to Pinheiro et al (2018), the electrochemical technique makes possible the evaluation of the antioxidant action by the synergism of the bioactive compounds, unlike the ABTS and DPPH tests, which are more specific for certain compounds. In addition, the electrochemical technique presents simplicity in the analyzes and high performance (Jiang et al, 2019).…”

“…In recent years, research has reported on the importance of the pequi in relation to antioxidant capacity, attributed mainly to pulp, due to its composition rich in compounds with antioxidant properties (Ferreira et al, 2021a;Ferreira et al, 2021b;Nascimento, Alves, Silva, & Naves, 2017;Pinheiro et al, 2018;Ribeiro, Fernandes, Alves, Margareth, & Naves, 2014).…”