Currently, there is a growing interest in screening and quantifying antioxidants from biological samples in the quest for natural and effective antioxidants to combat free radical-related pathological complications. Antioxidant assays play a crucial role in high-throughput and cost-effective assessment of antioxidant capacities of natural products such as medicinal plants and food samples. However, several investigators have expressed concerns about the reliability of existing in vitro assays. Such concerns arise mainly from the poor correlation between in vitro and in vivo results. In addition, in vitro assays have the problem of reproducibility. To date, antioxidant capacities are measured using a panel of assays whereby each assay has its own advantages and limitations. This unparalleled review hotly disputes on in vitro antioxidant assays and elaborates on the chemistry behind each assay with the aim to point out respective principles/concepts. The following critical questions are also addressed: (1) What make antioxidant assays coloured? (2) What is the reason for working at a particular wavelength? (3) What are the advantages and limitations of each assay? and (4) Why is a particular colour observed in antioxidant–oxidant chemical reactions? Furthermore, this review details the chemical mechanism of reactions that occur in each assay together with a colour ribbon to illustrate changes in colour. The review ends with a critical conclusion on existing assays and suggests constructive improvements on how to develop an adequate and universal antioxidant assay.

中文翻译：

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食品科学和安全化学中抗氧化剂分析的多功能性，应用，优势和局限性。

当前，对从生物样品中筛选和定量抗氧化剂的兴趣日益增长，以寻求天然和有效的抗氧化剂以对抗自由基相关的病理并发症。抗氧化剂分析在高通量和经济有效的天然药物（例如药用植物和食品样品）抗氧化能力评估中起着至关重要的作用。但是，一些研究人员对现有体外测定的可靠性表示担忧。这种担忧主要是由于体外和体内结果之间的不良关联。另外，体外测定法具有再现性的问题。迄今为止，抗氧化剂能力使用一组测定法来测量，由此每种测定法都有其自身的优点和局限性。这项无与伦比的评论对体外抗氧化剂测定法提出了强烈争议，并详细阐述了每种测定法背后的化学性质，目的是指出各自的原理/概念。还解决了以下关键问题：（1）是什么使抗氧化剂测定变色？（2）在特定波长下工作的原因是什么？（3）每种测定法的优点和局限性是什么？（4）为什么在抗氧化剂-氧化剂化学反应中观察到特定的颜色？此外，本篇文章详细介绍了每种测定法中发生的反应的化学机理以及色带，以说明颜色的变化。审查以对现有检测方法的关键结论作为结尾，并提出了关于如何开发适当的通用抗氧化剂检测方法的建设性改进。