Re-evaluation of ABTS•+ Assay for Total Antioxidant Capacity of Natural Products

Abstract

2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS+) is a stable free radical frequently used for estimating the total antioxidant capacity (TAC) of natural products. The existing methods for ABTS+ radical-scavenging activity assays are diverse in pre-diluting solvents and reaction time, which lead to errors in the TAC estimations. To develop an effective and universal method for estimating the ABTS+ capacity accurately and reasonably, five pre-dilution solvents [methanol, ethanol, phosphate buffer (Na 2 HPO 4-NaH 2 PO 4 , 200 mM, pH = 7.4), PBS buffer (Na 2 HPO 4-NaH 2 PO 4-NaCl, 200 mM, pH = 7.4), and distilled water] and different reaction times were investigated in ABTS+ assays of five typical antioxidants. The results showed that the solvent effects were very significant. When using different pre-diluting solvents, different detection wavelengths should be selected. ABTS+ assay could be measured within 2-10 min to obtain a rough result, which was mostly 6 min in the literature. However, full and accurate evaluation of antioxidant reactivity rather than capacity requires recording ABTS+ loss continuously during the whole reaction period. The present study makes a recommendation for estimating the ABTS+ capacity accurately and reasonably.

ABTS/PP Decolorization Assay of Antioxidant Capacity Reaction Pathways

“…The usually applied characteristic maxima to monitor are 414-417 nm and 730-734 nm ( Table 2); however, the latter is the recommended range due to the possible interference of many samples, which can be expected at lower wavelengths, resulting in the underestimated antioxidant capacity [37]. It is important to consider that ABTS •+ absorbance maximum bands shift a little in different solvents due to the solvatochromic effect: methanol (744-745 nm), ethanol (753 nm), and propanol-1 (757 nm) [38,39]. The pH impacts the λ max either, for example, in 0.1 M acetate buffer pH 5 a hypsochromic shift is observed with a maximum at 728 nm [40].…”

Incidence of hydrocolloid type on quality parameters in mango leathers (Mangifera indica L.) Yulima variety

“…The ABTS test, due to its chemical bipolarity, tells about plant extracts' total antioxidant capacity (Dong et al, 2015), whereas the stabilizing ability of the DPPH radical is often correlated with the ascorbic acid concentration, which in presence of citric acid, improves the stabilizing action of the radical (Scalzo, 2008). Ot is presumed that the partial thermal degradation of phenolic compounds in the mango pasteurized leathers, and the addition of citric and ascorbic acid in the formulation, was able to generate a synergistic effect-compensatory between acids and antioxidant metabolites from the pulp (Machado et al, 2007;Noguer et al, 2014).…”

Chemical composition and antioxidant capacities analysis of different parts of Brasenia schreberi

“…ABTS radical scavenging assay of the different samples was measured according to the method previously reported (Dong, Cai, Xing, Yu, & Ding, 2015). The measured results were compared with the IC50 of the ABTS radical scavenging rate of Vc, which was set as standard.…”