Fabrication of an Eficient Antioxidant Capacity Assay Using Peroxidase-mimicking Trivalent DNAzyme

So far, several methods, including DPPH, FRAP and TEAC have been suggested for considering the antioxidant capacity, each with disadvantages, including the need for expensive tools, low sensitivity, and complexity. One of the most accurate methods is the TEAC method, due to the use of protein enzymes, which possesses disadvantages such as activity in the limited temperature range, and instability against hydrolysates and hard storage conditions. Therefore, antioxidant capacity measurements were performed using the peroxidase-like trivalent deoxyribozyme. The results showed that trivalent deoxyribozyme has more catalytic activity than monomeric deoxyribozyme. Also, kinetic parameters such as kcat, Km, and Vmax were calculated in the presence of H2O2, which were equal to 4.32 (min-1), 8.744 (μM), and 0.864 (μM min-1), respectively. The results of calculating RAC for the extracts of Dacrocephalum and Black cardamom plants were estimated to be 28.59 and 11.79, respectively. Also, the limit of detection (LOD) found for trolox, ferulic acid, and caffeic acid was about o.27, 0.14 and 0.28 (μM), respectively, by UV-Vis spectroscopy. The LOD values were 5.0, 2.0 and 2.5 (μM) by the naked eye for the mentioned antioxidants, respectively. These results indicated that antioxidant capacity measurements using the peroxidase-like trivalent deoxyribozyme have advantages such as cheapness, simplicity, observation with naked eye, stability, and high sensitivity to the other methods.