<p class="first" id="d35170265e53">Antioxidants had a growing interest owing to their
protective roles in food and pharmaceutical
products against oxidative deterioration and in the body and against oxidative stress-mediated
pathological processes. Screening of antioxidant properties of plants and plant-derived
compounds requires appropriate methods, which address the mechanism of antioxidant
activity and focus on the kinetics of the reactions including the antioxidants. Many
studies evaluating the antioxidant activity of various samples of research interest
using different methods in food and human health have been conducted. These methods
are classified, described, and discussed in this review. Methods based on inhibited
autoxidation are the most suited for termination-enhancing antioxidants and for chain-breaking
antioxidants, while different specific studies are needed for preventive antioxidants.
For this purpose, the most common methods used in vitro determination of antioxidant
capacity of food constituents were examined. Also, a selection of chemical testing
methods was critically reviewed and highlighted. In addition, their advantages, disadvantages,
limitations and usefulness were discussed and investigated for pure molecules and
raw extracts. The effect and influence of the reaction medium on the performance of
antioxidants are also addressed. Hence, this overview provides a basis and rationale
for developing standardized antioxidant methods for the food, nutraceuticals, and
dietary supplement industries. In addition, the most important advantages and shortcomings
of each method were detected and highlighted. The chemical principles of these methods
are outlined and critically discussed. The chemical principles of methods of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulphonate)
radical (ABTS·+) scavenging, 1,1-diphenyl-2-picrylhydrazyl (DPPH·) radical scavenging,
Fe3+-Fe2+ transformation assay, ferric reducing antioxidant power (FRAP) assay, cupric
ions (Cu2+) reducing power assay (Cuprac), Folin-Ciocalteu reducing capacity (FCR
assay), peroxyl radical (ROO·), superoxide radical anion (O2·-), hydrogen peroxide
(H2O2) scavenging assay, hydroxyl radical (OH·) scavenging assay, singlet oxygen (1O2)
quenching assay, nitric oxide radical (NO·) scavenging assay and chemiluminescence
assay are outlined and critically discussed. Also, the general antioxidant aspects
of main food components were discussed by a number of methods, which are currently
used for the detection of antioxidant properties of food components. This review consists
of two main sections. The first section is devoted to the main components in the food
and pharmaceutical applications. The second general section comprises some definitions
of the main antioxidant methods commonly used for the determination of the antioxidant
activity of components. In addition, some chemical, mechanistic and kinetic basis,
and technical details of the used methods are given.
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