Department of Chemistry, Sechenov First Moscow State Medical University, Trubetskaya Str. 8/2, 119991 Moscow, Russia.
Int J Mol Sci. 2020 Feb 8;21(3):1131. doi: 10.3390/ijms21031131.
The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation-based assays are among the most abundant antioxidant capacity assays, together with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-based assays according to the Scopus citation rates. The main objective of this review was to elucidate the reaction pathways that underlie the ABTS/potassium persulfate decolorization assay of antioxidant capacity. Comparative analysis of the literature data showed that there are two principal reaction pathways. Some antioxidants, at least of phenolic nature, can form coupling adducts with ABTS, whereas others can undergo oxidation without coupling, thus the coupling is a specific reaction for certain antioxidants. These coupling adducts can undergo further oxidative degradation, leading to hydrazindyilidene-like and/or imine-like adducts with 3-ethyl-2-oxo-1,3-benzothiazoline-6-sulfonate and 3-ethyl-2-imino-1,3-benzothiazoline-6-sulfonate as marker compounds, respectively. The extent to which the coupling reaction contributes to the total antioxidant capacity, as well as the specificity and relevance of oxidation products, requires further in-depth elucidation. Undoubtedly, there are questions as to the overall application of this assay and this review adds to them, as specific reactions such as coupling might bias a comparison between antioxidants. Nevertheless, ABTS-based assays can still be recommended with certain reservations, particularly for tracking changes in the same antioxidant system during storage and processing.
2,2'-偶氮双（3-乙基苯并噻唑啉-6-磺酸）（ABTS）自由基阳离子测定法是最常用的抗氧化能力测定法之一，根据 Scopus 引文率，与 2,2-二苯基-1-苦基肼（DPPH）自由基测定法一起。本综述的主要目的是阐明 ABTS/过硫酸钾褪色法测定抗氧化能力的反应途径。对文献数据的比较分析表明，存在两种主要的反应途径。一些抗氧化剂，至少是酚类物质，可以与 ABTS 形成偶联加合物，而其他抗氧化剂可以在不发生偶联的情况下进行氧化，因此偶联是某些抗氧化剂的特异性反应。这些偶联加合物可以进一步发生氧化降解，分别生成带有 3-乙基-2-氧代-1,3-苯并噻唑啉-6-磺酸盐和 3-乙基-2-亚氨基-1,3-苯并噻唑啉-6-磺酸盐的腙基和亚胺类加合物，作为标记化合物。偶联反应对总抗氧化能力的贡献程度以及氧化产物的特异性和相关性需要进一步深入阐明。毫无疑问，人们对该测定方法的总体应用存在疑问，本综述增加了这些疑问，因为偶联等特定反应可能会影响抗氧化剂之间的比较。尽管如此，ABTS 测定法仍可推荐使用，但需有一定的保留意见，特别是在跟踪储存和加工过程中同一抗氧化系统的变化时。
