Electrochemical study of the interactions between anionic species of menadione and alkylated nucleobases in dimethylsulfoxide

Abstract

The electrochemical behavior of menadione reduction (MQ) in the presence of alkylated derivatives of the following nucleobases is reported for the first time in the present work: 9-nonyladenine (NAH), 1-nonylthymine (NTH), 1-nonylcytosine (NCH), and 9-phenylethylguanine (PEGH). Through voltammetric simulation, it was possible to characterize the MQ reduction mechanisms in the presence of NAH and NCH, including the hydrogen-bonding association between reduced species of menadione and nucleobases. In the case of the NAH nucleobase, the best fit between the simulated and the experimental voltammograms was achieved when a comproportionation reaction involving MQ2−(NAH) and MQ is considered. The analysis of MQ voltammograms with different NTH concentrations led to the formation of an MQ.−(NTH) association complex, and the concerted reduction and deprotonation of MQ.−(NTH) resulted in the protonated species MQH−, in agreement with the literature. Finally, in the case of the reduction of MQ with PEGH, the voltammetric response, evinced the protonation process of the semiquinone and confirmed a second-order disproportionation mechanism.