Ru^III(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

Reactivity of polyaminocarboxylatoruthenium(III) complexes with serine and their protease inhibition

Reaction of [Ru(edta)(H2O)]� (edta4�¼ethylenediaminetetraacetate), [Ru(pdta)(H2O)]� (pdta4�¼propylenediaminetetraacetate) and [Ru(hedtra)(H2O)] (hedtra3�¼N-hydroxyethylethylenediaminetriacetate) with S-serine (Ser) was studied spectrophotometrically and kinetically. Serine protease inhibition studies were performed with the three complexes using the serine protease enzymes chymotrypsin and subtilisin with azoalbumin as substrate. Results are discussed in terms of the reactivity of the Ru-pac (pac¼polyaminopolycarboxylates) complexes with serine. The order of protease inhibition efficacy of the Ru-pac complexes is [Ru(pdta)(H2O)]�>[Ru(edta)(H2O)]��[Ru(hedtra)(H2O)], in good agreement with the observed reactivity of Ru-pac complexes with serin