Total Antioxidant Capacity of Some Commercial Fruit Juices: Electrochemical and Spectrophotometrical Approaches

Abstract

The aim of this paper was to assess the total antioxidant capacity of some commercial fruit juices (namely citrus), spectrophotometrically and by the biamperometric method, using the redox couple DPPH· (2,2-diphenyl-1-picrylhydrazyl)/DPPH (2,2-diphenyl-1-picrylhydrazine). Trolox® was chosen as a standard antioxidant. In the case of the spectrophometric method, the absorbance decrease of the DPPH· solution was followed. For the biamperometric method, the influence of some parameters like the potential diference, ΔE, DPPH· concentration, and Trolox® concentration was investigated. The calibration graph obtained for Trolox® presents linearity between 5 and 30 µM, (y = 0.059 x + 0.0564, where y represents the value of current intensity, expressed as μA and x the value of Trolox® concentration, expressed as μM; r2 = 0.9944). The R.S.D. value for the biamperometric method was 1.29% (n = 10, c = 15 μM Trolox®). In the case of the spectrophotometric method, the calibration graph obtained for Trolox® presents linearity between 0.01 and 0.125 mM (y = -9.5789 x+1.4533, where y represents the value of absorbance and x, the value of Trolox® concentration, expressed as mM; r2 = 0.9963). The R.S.D. value for the spectrophotometric method was 2.05%. Both methods were applied to total antioxidant activity determination in real samples (natural juices and soft drinks) and the results were in good agreement.

Atypical antidepressants extend lifespan of Caenorhabditis elegans by activation of a non‐cell‐autonomous stress response

“…1E). Free radical‐scavenging activity of a compound in vitro can be monitored using the free radical DPPH that absorbs light at 520 nm, while its reduced form does not (Pisoschi et al ., 2009). Neither Mirtazapine nor Mianserin showed a DPPH‐scavenging activity at any relevant concentration.…”

“…The DPPH radical absorbs light at 520 nm, while its reduced form does not, allowing to monitor scavenging activity (Pisoschi et al ., 2009). Mianserin, Mirtazapine, and Trolox stock solutions (10x) were prepared in ethanol (see Appendix S1 for catalog numbers and chemical information) and tested at increasing concentrations for their ability to scavenge DPPH (90 μ m ) using ethanol as a negative control.…”

Electrochemical Methods for Total Antioxidant Capacity and its Main Contributors Determination: A review

“…The molar ratio DPPH•/DPPH should be carefully chosen: in studies using this redox couple, conditions were employed with a DPPH• concentration lower than the DPPH one, so the measured current intensity is limitated by the smaller concentration of the radical [23,114]. Antioxidant addition diminishes the concentration of DPPH• and increases the concentration of DPPH, thus giving rise to a current linearly dependent on antioxidant concentration [23,114].…”

“…The reverse relationship between the consumption of fruits and vegetables and the development of oxidative stress-related disorders, confirmed by epidemiological studies, has been attributed to the presence of compounds endowed with high antioxidant activity [17][18][19][20]. The main biocompounds found in natural sources are phenolics (flavonoids or non-flavonoids), associated to health benefits resulted from the inhibition of low-density lipoprotein oxidation [19,[21][22][23][24][25].…”

Electrochemical Sensing of Ascorbic Acid on ZnO-decorated Reduced Graphene Oxide Electrode

“…Electrochemical determination of ascorbic acid is gaining interest due to its fast analysis, ability to detect lower concentrations, and simplicity of operation. Further, a lab-on-a-chip electrochemical sensing platform has the potential to simultaneously determine multiple antioxidants such as polyphenols as well as other micronutrients in a food sample [5,[10][11][12][13][14][15][16][17]. Therefore, the development of electrochemical sensing platforms that have the ability to determine multiple analytes relevant in nutritive food formulations and nutraceuticals is of paramount interest.…”