Critical Review—Electrochemical Properties of 13 Vitamins: A Critical Review and Assessment

Abstract

Review of the literature on the currently recognized, thirteen vitamins yields an overview of the electrochemical properties that include estimates of the formal potentials at physiological pH and identification of the general classes of redox mechanisms. All vitamins are electroactive and map a range of formal potentials E 0 over a 3 V window. The vitamins are grouped as lipid soluble (vitamins A, D, E, and K) and water soluble (B vitamins and vitamin C). Mechanisms are grouped as single electron transfer agents (B3, B7, B2, C, and D), vitamins that can be both oxidized and reduced (B1, B5, B6, B9, and E), and vitamins that undergo two successive, distinct reductions (B12 and K). Vitamin A voltammetry is uniquely complex. Plot of the formal potentials on a potential axis allows assessment of mechanistic paths to vitamin recycling, antioxidant behavior, pH dependence, electrochemical stability in air, acid, and water, electrochemical instability of vitamin pairs, and cooperative interactions between vitamins in medicine. The potential axis is shown as an effective tool for mapping thermodynamically complex interactions. By modern standards, the US federal government identifies 13 vitamins.3 The water soluble vitamins are vitamin C and the eight B vitamins (B1, B2, B3, B5, B6, B7, B9, B12). The lipid or fat soluble vitamins are A, D, E, and K. The fat soluble vitamins can accumulate in the body whereas the water soluble vitamins do not. There are no current vitamins designated beyond E except for K because materials historically assigned the interposed letter designations either no longer fall under the modern definition of vitamin or several related materials were reclassified. Several vitamins exist in different but related chemical structures.Questions considered in this perspective include whether all vitamins are electroactive; what is the redox potential of the vitamins; what are the kinetics and mechanisms of vitamins on oxidation and reduction; when are vitamins antioxidants; are vitamins stable to water and oxygen; do vitamins interact cooperatively. Although papers are available on the electrochemistry and voltammetry of individual vitamins, no single resource summarizes the electrochemical data for all vitamins. This review compiles and critically assesses the available literature on vitamin voltammetry. The compiled data serve to develop perspective on the electrochemical properties of vitamins and the role of vitamins individually and collectively as electroactive species. This CRES 3 T review assimilates fundamentals of thermodynamics and estimated formal potentials, kinetics, and mechanisms as assessed voltammetrically for individual vitamins to provide perspective on the collective electrochemical properties of the thirteen vitamins. Perspective on vitamin electrochemical properties may contribute to assess yet more complex bioelectrochemical processes. * Electrochemical Society Student Member.* * Electrochemical Society Fellow. z E-mail: johna-leddy@uiowa.eduThe review contains two main sections....

Improving the Stability of EGFR Inhibitor Cobalt(III) Prodrugs

“…For AA, usually 0.06 V for dehydro- l -ascorbate/AA at pH 7.0 is reported. 42 However, recent literature also suggests even higher values in the range of 0.35–0.50 V. 43 , 44 GSH is produced in cells at concentrations (1–10 mM) at least one order of magnitude higher than those of NADH (30–100 μM). 45 , 46…”

The acid–base and redox properties of menaquinone MK-4, MK-7, and MK-9 (vitamin K2) in DMPC monolayers on mercury

“…A very recent review of the electrochemistry of vitamins highlights the importance of solid thermodynamic data, and it also shows that no reliable data concerning Vitamin K are available (Lovander et al 2018). Vitamin K, in its hydroquinone state, functions as an exclusive coenzyme of γ-glutamyl carboxylase (GGCX, EC 4.1.1.90), which catalyzes the post-translational γ-carboxylation of a number of vitamin K-dependent proteins (Kleuser 2018).…”

Quick and Cost-Effective Estimation of Vitamin C in Multifruit Juices Using Voltammetric Methods

“…This asseveration is justified as follows. As depicted in [44], 10·10-5 M of Vitamin B1 produces a current response around 0.8 µA. Assuming a linear behavior in all the concentration intervals, the higher amount of B1 found in juices (0.092 mg as showed in Table 2) would entail a negligible current response of around 0.31 µA.…”

“…First, the sugar is the compound which is in higher proportion in the juices (the water is not considered in this study because it is not electroactive), followed by potassium, vitamin C, magnesium, phosphorus, calcium, sodium, and other vitamins such as B1, B2, B6, A, E, and K. According to [40], both magnesium and calcium have a negative oxidation potential, very distant from the AA one, which does not imply a significant interference. In the same way, potassium [41] and most of the vitamins, such as B2 voltammetric [42], B6 [43], A, E, and K [44], have a very different oxidation potential with respect to the AA oxidation potential. Regarding vitamin B1, it is an exception since its oxidation potential is around 0.6 V. However, the calculated TIE is very low, and the resulting interference is not remarkable either.…”