Redox Mechanism, Antioxidant Activity and Computational Studies of Triazole and Phenol Containing Schiff Bases

Abstract

Electrochemical behavior of three biologically important triazole and phenol containing Schiff bases (E)-3-((4H-1,2,4 triazol-4ylimino) methyl)benzene-1,2-diol (TMB), (E)-3-((4H-1,2,4 triazol-4-ylimino) methyl)para-phenol (p-TMP) and (E)-3-((4H-1,2,4 triazol-4-ylimino) methyl)ortho-phenol (o-TMP) were investigated by electrochemical, spectroscopic and computational methods. The peak potential of all the three compounds showed a linear dependence on pH under acidic conditions, but under alkaline conditions, electron transfer was not coupled to proton transfer. The acid-base dissociation constant (pKa) values of the compounds were evaluated both by electrochemical and UV-Vis spectroscopic techniques. On the basis of experimental and theoretical findings, redox mechanisms of the compounds were proposed and certain important kinetic and thermodynamic parameters were determined from their temperature and pH responsive redox response. Our studies showed a) low cytotoxicity for all three triazoles and b) antioxidant properties of these triazoles. TMB was found as the most promising antioxidant, which makes this compound interesting as a basis for further development as food supplement.

Colorimetric Detection of Antioxidants in Food Samples Using MnO2/Graphene Quantum Dot Composites with Oxidase-like Activity

“…The limits of detection (LODs) were calculated by 3σ/S (where σ is the standard deviation of the lowest concentration, and S is the slope of the calibration curve) for the three analytes and were found to be 0.07, 0.28, and 0.69 μmol L –1 for GA, TA, and AA, respectively. It is worth noting that the narrow concentration range obtained for the detection of TA is due to its structure (Figure S2), which contains more hydroxyl groups available to participate in the reduction of the oxTMB substrate . In this way, a smaller amount of TA is sufficient to produce the same color change as higher concentrations of GA.…”

“…It is worth noting that the narrow concentration range obtained for the detection of TA is due to its structure (Figure S2), which contains more hydroxyl groups available to participate in the reduction of the oxTMB substrate. 53 In this way, a smaller amount of TA is sufficient to produce the same color change as higher concentrations of GA.…”

Comparative analysis of oxidative mechanisms of phloroglucinol and dieckol by electrochemical, spectroscopic, cellular and computational methods

“…4A ). The number of electrons ( n ) and protons ( m ) involved in PL oxidation can be obtained from half peak width ( W 1/2 ) of DPVs and slope of the plots of E p as a function of pH using equations 18 and 19 α value, the anodic charge transfer coefficient, was evaluated from equation 20 where E p/2 is the potential where the current is at half the peak value. We obtained W 1/2 ≈ 130 mV and α = 0.75 for peak 1a of PL, therefore, the ratio of protons to electrons ( m : n ) involved in the oxidation process of PL was calculated as 0.9 : 1 ≈ 1 : 1.…”

Voltammetric, spectroscopic, and cellular characterization of redox functionality of eckol and phlorofucofuroeckol‐A: A comparative study

“…The DPVs of EL solution exhibited a linear region in the E p versus pH plots for E pa 1 , E pa 2 , and E pa 3 in the range of 2.0 ≤ pH ≤ 7.0 (Figure a). Considering the reversibility of redox process of EL, it can be assumed that anodic charge transfer coefficient α = 0.5, thus according to following Equations (2) and (3) (Nimal et al, ) and the slope of E p –pH plots (Table ), the number of electron ( n ) and proton ( m ) transfer corresponding to individual step of EL oxidation can be calculated, which are listed in Table .…”

“…The oxidation patterns of EL and PFF-A in both cyclic and DP voltammograms were highly pH-dependent. As depicted in Figure 3a can be assumed that anodic charge transfer coefficient α = 0.5, thus according to following Equations (2) and (3) (Nimal et al, 2016) and…”