Theoretical investigation of the alloxan-dialuric acid redox cycle

Abstract

The redox cycle between alloxan, a mild oxidizing agent, and its reduction partner, dialuric acid, is investigated using density functional theory. It is found that the initial step is the one‐electron reduction of alloxan followed by protonation, yielding a stable neutral radical, AH·. The radical can then accept another electron to form the dialuric acid anion. The formation of this anion is thermodynamically favored in both the gas phase and in solution. The radical may also undergo dimerization to alloxantin, followed by the transfer of a proton from one moiety to another, yielding alloxan and dialuric acid. This reduction is thermodynamically feasible in the gas phase, but not in aqueous solution. In the case of reduction of alloxan by glutathione at the physiological pH, computed redox potentials indicate that a two‐electron reduction is the favored course of reaction, yielding directly the dialuric acid anion, which then undergoes aerial oxidation to yield the superoxide radical. The redox cycling between alloxan and dialuric acid is responsible for the diabetogenic activity of alloxan, producing cytotoxic radicals on reoxidation of dialuric acid. © 2013 Wiley Periodicals, Inc.

Determination of reduced glutathione by spectrophotometry coupled with anti-interference compensation

“…The detection principle is that the GSH reacts with alloxan and oxygen in alkaline conditions, generates a substance with a highest absorption peak at 305 nm, utilizing absorbance with a certain concentration of GSH showing a linear relationship to detect the concentration of GSH. 14,15 To date, the alloxan method hasn't been reported for the detection of the content of GSH in enzymatic reaction liquid, with the elimination of Cys interference.…”

Family Tree for Aqueous Organic Redox Couples for Redox Flow Battery Electrolytes: A Conceptual Review

“…The best-known relative of alloxan-type compounds is the barbituric acid, which is the mother compound of the earliest sleeping drugs, such as barbital. The compound alloxan itself is a mild oxidation agent with a formal potential of around −0.145 V (vs. SHE, at pH 7.4) [130], with the reduced form dialuric acid.…”

A theoretical assessment of the structural and electronic features of some retrochalcones

“…The NICS values were computed at the GIAO‐SCF/6‐311++G** level [24]. The gas and solution phase basicities and sequential p K a values of each deprotonation site were calculated using the procedure reported in our previous work [25].…”

“…Retrochalcones contain two or three hydroxyl groups which may get ionized depending on the pH of the medium. Thus, we have calculated the p K a value of each hydroxyl group present in compounds 1–6 for the step‐wise proton release in aqueous solution using the same methodology as that reported in our previous work [25]. GPB refers to the gas‐phase basicity and was computed as the negative of the Gibbs energy change for the protonation of the mono, di and tri‐anionic forms of the retrochalcones corresponding to p K a 1 , p K a 2 , and p K a 3 , respectively, in the gas phase.…”