Redox Reactions of a [RuIII(hedtra)(pz)] Complex with Biochemically Important Reductants: Kinetic, Mechanistic and Antimicrobial Studies

Abstract

AbstractThe kinetics of the reduction of [RuIII(hedtra)(pz)] (hedtra3– = N‐hydroxyethylethylenediaminetriacetate; pz = pyrazine) by biologically important reducing agents, Red (Red = L‐ascorbic acid, catechol and cysteine), resulting in the formation of the corresponding red‐coloured ruthenium(II) complex has been studied spectrophotometrically using both conventional mixing and stopped‐flow techniques. The time course of the reaction was followed as a function of [Red], pH and temperature. Alkali metal ions were found to have an insignificant effect on the reaction rate. Kinetic data and activation parameters are interpreted in terms of an outer‐sphere electron‐transfer mechanism, and discussed with reference to the data reported for the corresponding RuIII–edta (edta4– = ethylenediamineteraacetate) complex. The antibacterial activity of the [RuIII(hedtra)(pz)] complex in inhibiting the growth has been explored. Results of the biological studies have been discussed in terms of the cleavage of chromosomal DNA of the bacteria by the [RuIII(hedtra)(pz)] complex in the presence of cysteine under aerobic conditions.