Electrochemical Oxidation of Guanosine and Xanthosine at Physiological pH: Further Evidences of a Convergent Mechanism for the Oxidation of Purine Nucleosides

Abstract

The electrochemical oxidation of guanosine and xanthosine, which only differ in the presence of an oxygen atom at C2 position instead of an amine group, is studied on pyrolytic graphite electrodes at different electrolysis time scales in solutions of physiological pH. The oxidation products adsorbed on the electrode surface were electrochemical characterized in terms of variation of the formal potential with pH and catalytic activity towards the oxidation of NADH. The results were compared with those previously described for the oxidation of guanosine and adenosine in alkaline solutions. A common oxidation product is described, the oxidized form of 9-b-d-ribofuranosyluric acid, which is proposed as the point of convergence in the oxidation routes of all three purine nucleosides.

Nanoporous Nickel Microspheres: Synthesis and Application for the Electrocatalytic Oxidation and Determination of Acyclovir

“…Acyclovir bears two major groups of the guanine analog and the first-type alcohol. As a guanine derivative, acyclovir can be oxidized to the corresponding oxoguanine analog: 31,32 (10) In addition, as a primary alcohol, acyclovir, can also be oxidized to the corresponding aldehyde and/or carboxylic acid on nickel-based electrodes: 33 (11) (12) Figure 5 shows cyclic voltammograms of MCPE/Nf in a range of potential sweep rates of 2 to 100 mV s -1 in the presence of 300 μmol L -1 acyclovir. Upon increasing the potential sweep rate, the anodic peak current increased, and depended linearly on the square root of the potential sweep rate (Fig.…”

Electrocatalytic evaluation of DNA damage by superoxide radical for antioxidant capacity assessment

“…According to previous studies on the electro-oxidation of adenine derivatives on carbon electrodes in phosphate buffer [28,32,33], the compound responsible for redox process at +0.041 V is a diimine species strongly adsorbed on the electrode surface. This compound was also identified after oxidation of guanine derivatives [25][26][27]. Therefore, it can be concluded the existence of a common lesion on DNA generated by O ÅÀ 2 generated by the xanthine/XOD system and by electrochemical oxidation.…”

“…Based on previous work on electrochemical oxidation of adenine and guanine derivatives [25][26][27][28], a minor product of the radical oxidation was identified. The oxidative lesions were indirectly quantified after electrochemical oxidation of the remaining intact adenine bases to generate a well-known catalyst species that mediates the oxidation of NADH.…”

A simple and low-cost electrochemical sensor based on a graphite sheet electrode modified by carboxylated multiwalled carbon nanotubes and gold nanoparticles for detection of acyclovir

“…The oxidation mechanism can be explained by the three-step mechanism described in Scheme 4. 51,52 The product formed after two proton two electron exchange is 8-oxoacyclovir, which is structurally similar to the preliminary oxidation product of guanine. The proposed oxidation mechanism for this process is shown in Scheme 4.…”