[RuIII(medtra)(H2O)] (medtra = N-methyl.ethylenediaminetriacetate) complex -: A highly efficient NO inhibitor with low toxicity

Stopped-flow kinetic measurements were used to compare the reactivities of [Ru(medtra)(H2O)] (medtra(3-) = N-methylethylenediaminetriacetate) (1) and [Ru(hedtra)(H2O)] (2) (hedtra(3-) = N-hydroxyethylethylenediaminetriacetate) with NO in aqueous solution at 15 degrees C, pH 7.2 (phosphate buffer). The measured second-order rate constants (3 x 10(3) and 6 x 10(4) m(-1) s(-1) for 1 and 2, respectively) are three to four order of magnitudes lower than that for the reaction between [Ru-III(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. (c) 2006 Elsevier B.V. All rights reserved.