Reactive nitrogen and oxygen species are produced in cells and play an important role in the oxidative metabolism; when in abnormal concentrations, they are able to induce oxidative damage on biomolecules, namely in DNA. In this paper it is described, an electrochemical DNA-based sensor against NO center dot radical developed for total antioxidant capacity (TAC) evaluation. The sensor consisted on dA(20) (adenine-rich oligonucleotide) physically adsorbed into carbon paste electrode (CPE). When this dA(20)-CPE was damaged, by immersion in a freshly generated NO center dot radical, a protective effect onto dA(20) was observed in the presence of antioxidants (ascorbic, gallic, caffeic, p-coumaric acids). Electrochemical studies were performed through square wave voltammetry. The construction of the sensor is simple, fast and the results indicated that the DNA-based sensor is suitable, accurate, and can be used to the assessment of TAC in commercial samples of juices. (C) 2016 Elsevier B.V. All rights reserved.