In vitro effect of stobadine on Fe(2+)-induced oxidative stress in rat liver mitochondria.

The authors have studied the susceptibility of two key protective enzymes, glutathione peroxidase (GPX) and glutathione reductase (GR) to the reactive oxygen species (ROS) known to induce oxidative damage in vitro system containing Fe2+/EDTA. The ability of ROS scavanger stobadine to prevent oxidative damage was also studied. Incubation of GPX with Fe2+/EDTA resulted in the significant decrease in its enzyme activity while under the same condition the activity of GR was not changed. The presence of stobadine was effective in protecting GPX from the loss of its activity by in vitro oxidizing agents. The monitoring of the mitochondrial outer membrane dynamics by the method of synchronous fluorescence fingerprint showed that the membrane is involved in these processes. (Fig. 3, Ref. 35.)

[Fe2+-induced oxidative processes in the liver mitochondria of rats]. / Oxidacné procesy mitochondrií pecene potkana indukované Fe2+.

The study investigated the prooxidative in vitro effect of various Fe(2+)-EDTA concentrations on biochemical parameters of the energetic metabolism of rat liver mitochondria. Fe(2+)-EDTA was added in concentrations 150, 300 and 400 mmol/mg of mitochondrial protein. The study included the investigation of consumption of oxygen in state 4 (without ADP addition) and in state 3 (with ADP addition), and the activities of ATP-ase, superoxide dismutase (SOD) and glutathione reductase. The mitochondrial outer membrane dynamics were simultaneously monitored by the method of synchronous fluorescence fingerprint. When compared with the control group, the results imply that in state 4, the addition of 150 mmol of Fe2+/mg of mitochondrial protein caused an insignificant increase in respiration to 104%, whereas in state 3, the oxygen consumption was insignificantly inhibited to 82%. The activity of ATPase was insignificantly raised to 105%, whereas the superoxide dismutase activity has decreased significantly to 77%. The activity of glutathione reductase increased significantly to 124%. The addition of 300 mmol of Fe2+/mg of mitochondrial protein has caused a significant inhibition of oxygen consumption to 67% in state 4 and to 31% in state 3. The activity of ATPase showed an insignificant elevation to 104%. The activity of superoxide dismutase was significantly reduced to 52% and that of glutathione reductase dropped to 72%. The addition of 400 Fe2+/mg of mitochondrial protein strongly diminished the oxygen consumption to 36% in state 4, and similarly to 37% in state 3. The activity of ATP-ase was significantly decreased to 39%, the superoxide dismutase activity diminished to 17% and glutathione reductase activity dropped to 37%. The monitoring of the mitochondrial outer membrane by the analysis of synchronous fluorescence fingerprint showed that the membrane is involved in these processes. (Fig. 5, Ref. 12.)

Stobadine and heart mitochondria.

Previous work has shown, that stobadine-hydrochloride (-)cis-2,8-dimethyl-2,3,4,4a,5,9b-hexahydro-14-pyrido(4,3b) indole administered in a single dose 2 mg/kg of body weight reduces cardiotoxic effect of isoproterenol (1 mg/kg) as shown by lowered serum enzyme activities of AST, CPK, LDH and ALT. We studied the effect of stobadine in vivo on respiration, the level of ATP, malondialdehyde (MDA) and superoxiddismutase (SOD) in heart mitochondria. Serum enzyme activities of AST, CPK and LDH after stobadine application were significantly decreased. In mitochondria, respiration and activity of SOD were inhibited, level of MDA was increased and level of ATP was unchanged. The cardioprotective effect of stobadine is not linked to preservation of mitochondrial function. This effect is probably more complex and mediated on the level of the whole organism.

[Peroxidative effects of tetracycline antibiotics]. / Prooxidacní úcinok tetracyklínových antibiotík.

After six-day administration of rolitetracycline (RTC) in the cardiac mitochondria of old rabbits the rate of oxygen consumption (glutamate-malate as well as 2-oxoglutarate) declines, while the malonic dialdehyde (MDA) rises. This provides evidence of more intense lipoperoxidation due to rolitetracycline. However, the ATP-ase activity increases and therefore this parameter is unsuitable in this experimental set-up (presence of tetracycline antibiotic) as an indicator of impaired integrity of mitochondrial membranes. After administration of RTC the activity of superoxide dismutase (SOD) increases markedly, but in case of concurrent administration of vitamin E it declines which is evidence of the prooxidative action of tetracyclines. Tetracycline itself and its metabolites which are formed during the biotransformation and degradation of epianhydrotetracycline (ETC) do not alter significantly the oxygen consumption nor the ATP-ase activity in cardiac mitochondria of old rabbits in vitro. Of these metabolites only anhydrotetracycline (ATC) and in particular epianhydrotetracycline (EATC) inhibit both parameters. From experiments in vitro ensues the relationship between the action and structure of the antibiotic and its metabolites the structure of cycle C and the nature of the substituents in positions C6 and C1 of this tetracycline cycle, as prerequisites are created for the formation of prooxidative structures.

[The effect of tetracycline and vitamin E on energy metabolism in cardiac mitochondria of old rabbits pretreated with isoproterenol]. / Ucinok tetracyklínu a vitamínu E na energiu mitochondrií srdca starých králikov po izoproterenolovej premedikácii.

The possibility of eliminating adverse effects of tetracycline and isoproterenol pretreatment on energy generation of myocardial mitochondria by vitamin E administration was investigated in old rabbits. Vitamin E administered in doses of 1.5 mg per kg body weight over 6 days was found to improve energy metabolism in old rabbits whose metabolism had been deranged by isoproterenol pretreatment in the dose of 1.5 mg per kg body weight. Subsequent administration of vitamin E to rabbits pretreated with isoproterenol and tetracycline in doses of 15 mg per kg body weight daily over 6 days also resulted in improvement of energy metabolism parameters studied. Under the given conditions vitamin E was found to exert a protective effect on oxidative phosphorylation of the myocardium damaged by isoproterenol and tetracycline.