Antioxidant Activity Evaluation in Biological Systems

Antioxidant activity evaluation in biological systems encompasses a range of chemical, biochemical and cellular assays designed to measure the ability of compounds or extracts to neutralise reactive species and protect biomolecules from oxidative damage. In chemical assays, radical-scavenging capacity is often quantified by colourimetric or spectrophotometric methods such as DPPH•- and ABTS•⁺-scavenging, ferric-reducing antioxidant power (FRAP) and metal-chelation assays. Complementary cell-based models, employing cultured mammalian cells subjected to oxidative insults (for example via hydrogen peroxide or lipopolysaccharide stimulation), enable assessment of cytoprotection, modulation of inflammatory mediators and intracellular reactive oxygen species (ROS) levels. Advanced hyphenated techniques, notably ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-Q-orbitrap MS/MS), permit simultaneous identification and quantification of antioxidant constituents in complex matrices. Collectively, these approaches inform structure–activity relationships, reveal mechanistic pathways such as electron transfer and hydrogen-atom transfer, and guide the optimisation of dietary supplements, pharmaceuticals and cosmetic actives. The global significance of this research lies in its contribution to chronic-disease prevention, food preservation, skincare innovation and the rational design of redox-modulating therapeutics.

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Antioxidant Activity Evaluation in Biological Systems publication trend

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Technical terms

Reactive oxygen species (ROS): chemically reactive molecules derived from oxygen, including free radicals and peroxides, that can damage lipids, proteins and DNA.

DPPH•-scavenging assay: a colourimetric method that measures the capacity of antioxidants to quench the stable free radical DPPH•, monitored by a decrease in absorbance.

Ferric-reducing antioxidant power (FRAP): an assay that evaluates the ability of an antioxidant to reduce Fe³⁺ to Fe²⁺, indicated by the formation of a coloured ferrous–tripyridyltriazine complex.

Electron transfer (ET): a fundamental mechanism in antioxidant action whereby an electron is donated from the antioxidant to neutralise a radical species.

Hydrogen-atom transfer (HAT): a pathway in which an antioxidant transfers a hydrogen atom (proton plus electron) to a free radical, terminating radical chain reactions.

Metal chelation: the process by which antioxidants bind transition metal ions (e.g., Fe²⁺, Cu²⁺), preventing catalysis of radical-forming reactions.

UHPLC-Q-orbitrap MS/MS: an advanced liquid chromatography–mass spectrometry technique combining high chromatographic resolution with accurate-mass detection for compound identification and quantification.

References

1. Database-aided UHPLC-Q-orbitrap MS/MS strategy putatively identifies 52 compounds from Wushicha Granule to propose anti-counterfeiting quality-markers for pharmacopoeia. Chinese Medicine (2023).
2. Quercetin and Quercitrin Attenuates the Inflammatory Response and Oxidative Stress in LPS‐Induced RAW264.7 Cells: In Vitro Assessment and a Theoretical Model. BioMed Research International (2019).
3. Comparison of the Antioxidant Effects of Quercitrin and Isoquercitrin: Understanding the Role of the 6″-OH Group. Molecules (2016).