Redox Conversions of 5-Methyl-6-nitro-7-oxo-4,7-dihydro-1,2,4triazolo[1,5-a]pyrimidinide l-Arginine Monohydrate as a Promising Antiviral Drug

This article presents the results of a study of electrochemical transformations in aqueous and aprotic media of 5-methyl-6-nitro-7-oxo-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidinide l-arginine monohydrate (1a, Triazid) obtained by electrochemical methods and ESR spectroscopy. The effect of pH on the current and the reduction potential of 1a in an aqueous Britton–Robinson buffer solution was studied. It was found that 1a is irreversibly reduced in aqueous acidic media on a glassy carbon electrode in one stage with the participation of six electrons and the formation of 5-methyl-6-amino-7-oxo-1,2,4-triazolo[1,5-a]pyrimidin. The electroreduction of 1a in DMF on a background of tetrabutylammonium salts proceeds in two stages, controlled by the kinetics of second-order reactions. In the first stage, the reduction of 1a is accompanied by protonation by the initial compound of the basic intermediate products formed in the electrode reaction (self-protonation mechanism). The second quasi-reversible stage of the electroreduction 1a corresponds to the formation of a dianion radical upon the reduction of the heterocyclic anion 5-methyl-6-nitro-7-oxo-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidin, which is formed upon the potentials of the first peak. The ESR spectrum of the radical dianion was recorded upon electroreduction of Triazid in the presence of Bu4NOH. The effect of the formation of ion pairs on the reversibility of the second peak of the 1a transformation is shown. A change in the rate and regioselectivity of the protonation of the dianion radical in the presence of Na+ and Li+ ions is assumed. The results of studying the electroreduction of 1a by ESR spectroscopy with a TEMPO trap make it possible to assume the simultaneous formation of both a nitroxyl radical and a radical with the spin density localized on the nitrogen at the 4 position of the six-membered ring. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: This work was supported by the Russian Foundation for Basic Research (RFBR, project No. 19-29-08015 mk)

Acceleration and increase of hydrogen production by simultaneous fermentation of Clostridium butyricum and Rhodobacter sphaeroides on wine-vinasse substrate

A fermentation process for hydrogen production as a result of the simultaneous effect of Rhodobacter sphaeroides and Clostridium butyricum on a wine-vinasse substrate was realized in a single illuminated bioreactor. The kinetics of the cooperative process indicates rapid and enhanced production of hydrogen showing yield of 65.41 mmol/l vinasse with a mixed culture as compared to processes using the two bacteria separately that have yields of 27.41 and 25.49 mmol/l vinasse for Rhodobacter and Clostridium, respectively. The experiment with a mixture of the two bacteria revealed co-operative assimilation of almost all components studied in the following sequence: malic acid > lactic acid > residual sugars> tartaric acid > citric acid. The use of vinasse substrate for hydrogen production would be a significant ecological energy resource for enterprises producing wine brandies together with waste utilization