We report the dual facets of 2-methoxyestradiol, that causes cancer cell death, but on the other hand may play a key role as a neurotoxin.

a b s t r a c tThere is growing evidence of mitochondrial membrane raft-like microdomains that are involved in the apoptotic pathway. The aim of this study was to investigate the effect of methyl-beta-cyclodextrin (MbCD), being a well-known lipid microdomain disrupting agent and cholesterol chelator, on the structure and bioenergetics of rat liver mitochondria (RLM). We observed that MbCD decreases the function of RLM, induces changes in the mitochondrial configuration state and decreases the calcium chloride-induced swelling. These data suggest that disruption of mitochondrial raft-like microdomains by cholesterol efflux on one hand impairs mitochondrial bioenergetics, but on the other hand it protects the mitochondria from swelling.

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In this paper instrumental methods of carbon dioxide (CO2) detection in biological material were compared. Using cis-[Cr(C2O4)(pm)(OH2)2]+ cation as a specific molecular biosensor and the stopped-flow technique the concentrations of CO2 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 CO2 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 (H2O2) added directly to culture medium. Pyruvic acid is well known scavenger of H2O2 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 H2O2, which causes nonenzymatic decarboxylation of pyruvate and releases of CO2, water and acetate as final products. In this work for the first time we have correlated the concentration of CO2 dissolved in culture medium with pyruvate's oxidant-scavenging abilities. Moreover, the kinetics of the reaction between aqueous solution of CO2 and coordinate ion, cis-[Cr(C2O4)(pm)(OH2)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.