[RuIII(medtra)(H2O)] (medtra = N-methylethylenediaminetriacetate) complex – A highly efficient NO inhibitor with low toxicity

Stopped-flow kinetic measurements were used to compare the reactivities of [Ru(medtra)(H2O)] (medtra3− = N-methylethylenediaminetriacetate) (1) and [Ru(hedtra)(H2O)] (2) (hedtra3− = N-hydroxyethylethylenediaminetriacetate) with NO in aqueous solution at 15 °C, pH 7.2 (phosphate buffer). The measured second-order rate constants (3 × 103 and 6 × 104 M−1 s−1 for 1 and 2, respectively) are three to four order of magnitudes lower than that for the reaction between [RuIII(edta)(H2O)]− (3) with NO. However, NO scavenging studies of complexes 1–3, conducted by measuring the difference in nitrite production between treated and untreated murine macrophage cells, revealed that despite being less kinetically reactive toward NO, the [Ru(medtra)(H2O)] complex exhibited the highest NO scavenging ability and lowest toxicity of compounds 1–3.