Measurement of antioxidant activity

Natural antioxidants are widely distributed in food and medicinal plants. These natural antioxidants, especially polyphenols and carotenoids, exhibit a wide range of biological effects, including anti-inflammatory, anti-aging, anti-atherosclerosis and anticancer. The effective extraction and proper assessment of antioxidants from food and medicinal plants are crucial to explore the potential antioxidant sources and promote the application in functional foods, pharmaceuticals and food additives. The present paper provides comprehensive information on the green extraction technologies of natural antioxidants, assessment of antioxidant activity at chemical and cellular based levels and their main resources from food and medicinal plants.

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Natural Antioxidants in Foods and Medicinal Plants: Extraction, Assessment and Resources

Because there is no widely adopted “total antioxidant parameter” as a nutritional index for labeling food and biological fluids, it is desirable to establish and standardize methods that can measure the total antioxidant capacity (TAC) level directly from plant-based food extracts and biological fluids. In this review, we (i) present and classify the widely used analytical approaches (e.g., in vitro and in vivo, enzymatic and nonenzymatic, electron transfer (ET)- and hydrogen atom transfer (HAT)-based, direct and indirect assays) for evaluating antioxidant capacity/activity; (ii) discuss total antioxidant capacity/activity assays in terms of chemical kinetics and thermodynamics, reaction mechanisms, and analytical performance characteristics, together with advantages and drawbacks; and (iii) critically evaluate ET-based methods for analytical, food chemical, biomedical/clinical, and environmental scientific communities so that they can effectively use these assays in the correct places to meet their needs.

http://pubs.acs.org/doi/pdf/10.1021/acs.jafc.5b04739

Antioxidant Activity/Capacity Measurement. 1. Classification, Physicochemical Principles, Mechanisms, and Electron Transfer (ET)-Based Assays.

Spices and herbs: Natural sources of antioxidants – a mini review

Reprint of “Hurdles and pitfalls in measuring antioxidant efficacy: A critical evaluation of ABTS, DPPH, and ORAC assays”

Kinetics and stoichiometry of reactions between the 2,2-diphenyl-1-picrylhydrazyl (DPPH) stable radical and 25 antioxidant compounds with different structure, molecular weight, number of −OH groups, and redox potential were investigated by recording the loss of DPPH• absorbance at 515 nm continuously for 10 min. A series of antioxidant concentrations was tested to determine linear response ranges and reaction saturation points. The primary feature distinguishing antioxidant activity—rate of initial reaction (<30 s)—was controlled by whether the dominant antioxidant mechanism was electron (very fast) or hydrogen atom (slow) transfer and by impairment of steric accessibility to the DPPH radical site by bulky ring adducts and multiple phenolic rings. Results raise serious questions regarding application of the DPPH assay for ranking antioxidants and natural extracts and suggest possible redirection of this assay to distinguish active reaction mechanisms by comparing reactions rates and patterns in different ...

Re-evaluation of the 2,2-Diphenyl-1-picrylhydrazyl Free Radical (DPPH) Assay for Antioxidant Activity

A review on rosemary as a natural antioxidation solution

Thinking outside the classical chain reaction box of lipid oxidation: Evidence for alternate pathways and the importance of epoxides

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Jia Xie

Papers

Reprint of “Hurdles and pitfalls in measuring antioxidant efficacy: A critical evaluation of ABTS, DPPH, and ORAC assays”

Re-evaluation of the 2,2-Diphenyl-1-picrylhydrazyl Free Radical (DPPH) Assay for Antioxidant Activity

A review on rosemary as a natural antioxidation solution

Thinking outside the classical chain reaction box of lipid oxidation: Evidence for alternate pathways and the importance of epoxides

Evidence for multiple oxidation pathways from non-volatile products of methyl linoleate