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Simultaneous Detection of Superoxide Anion Radical and Determination of Superoxide Scavenging Activity of Antioxidants Using a N,N-Dimethyl-p-phenylene diamine/Nafion Colorimetric Sensor

Abstract

The widely used nitroblue tetrazolium (NBT) colorimetric method for superoxide anion radical (O2•-) detection suffers from limitations such as formazan solubility and interferences by similar electron-donors. This work reports the development a novel assay for superoxide, where O2•- generated by the NADH/PMS/O2 system oxidizes the N,N-Dimethyl-p-phenylene diamine (DMPD) reagent to the pink-colored DMPD-semiquinone (DMPDQ) cationic radicals retained by a cation exchange Nafion® membrane and measured colorimetrically. Antioxidants exhibiting superoxide radical scavenging activity (SRSA) cause less DMPDQ radical production, resulting in attenuated color intensity on the Nafion® membrane, the absorbance difference (∆A) at 514 nm being proportional to antioxidant concentration. The developed method was applied to 14 antioxidant compounds including trolox, phenolic and hydroxycinnamic acids, flavonoids, and thiols, and the linear concentration ranges, calibration equations (as ∆A versus concentration), and trolox-equivalent antioxidant capacities of these antioxidants were established. The results were discussed in the light of structure-activity relationships. The method was used in measuring SRSA of antioxidant mixtures and green tea extract. The Nafion® membrane‒contacted green tea extract was transferred to an online-HPLC post-column CUPRAC system to measure unconsumed catechins. The percentage inhibitions for green tea found with the developed method were compared to those measured by the reference NBT method.

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Publication details

The article was received on 05 Sep 2017, accepted on 03 Oct 2017 and first published on 04 Oct 2017


Article type: Paper
DOI: 10.1039/C7AY02132A
Citation: Anal. Methods, 2017, Accepted Manuscript
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    Simultaneous Detection of Superoxide Anion Radical and Determination of Superoxide Scavenging Activity of Antioxidants Using a N,N-Dimethyl-p-phenylene diamine/Nafion Colorimetric Sensor

    F. Dondurmacıoglu, A. Avan and R. Apak, Anal. Methods, 2017, Accepted Manuscript , DOI: 10.1039/C7AY02132A

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