Coordinate cis-[Cr(C(2)O4)(pm)(OH(2))2](+) Cation as Molecular Biosensor of Pyruvate's Protective Activity Against Hydrogen Peroxide Mediated Cytotoxity

In this paper instrumental methods of carbon dioxide (CO(2)) detection in biological material were compared. Using cis-[Cr(C(2)O(4))(pm)(OH(2))(2)](+) cation as a specific molecular biosensor and the stopped-flow technique the concentrations of CO(2) released from the cell culture medium as one of final products of pyruvate decomposition caused by hydrogen peroxide were determined. To prove the usefulness of our method of CO(2) assessment in the case of biological samples we investigated protective properties of exogenous pyruvate in cultured osteosarcoma 143B cells exposed to 1 mM hydrogen peroxide (H(2)O(2)) added directly to culture medium. Pyruvic acid is well known scavenger of H(2)O(2) and, moreover, a molecule which is recognized as one of the major mediator of oxidative stress detected in many diseases and pathological situations like ischemia-reperfusion states. The pyruvate's antioxidant activity is described as its rapid reaction with H(2)O(2), which causes nonenzymatic decarboxylation of pyruvate and releases of CO(2), water and acetate as final products. In this work for the first time we have correlated the concentration of CO(2) dissolved in culture medium with pyruvate's oxidant-scavenging abilities. Moreover, the kinetics of the reaction between aqueous solution of CO(2) and coordinate ion, cis-[Cr(C(2)O(4))(pm)(OH(2))(2)](+) was analysed. The results obtained enabled determination of the number of steps of the reaction studied. Based on the kinetic equations, rate constants were determined for each step.