Activation of oxidative stress response by hydroxyl substituted chalcones and cyclic chalcone analogues in mitochondria.

We investigated the effect of hydroxyl substituted chalcone (1a) and some chalcone analogues (1b-d) on isolated rat liver mitochondria to gain new insights into the cytotoxic mechanism of these compounds. We observed an inhibitory effect on phosphorylation and the partial uncoupling of compounds 1a and 1d. Increased radical generation and possible covalent interaction of the compounds with cellular thiols resulted in glutathione (GSH) depletion and modulation of the investigated mitochondrial activities. Disruption of interconnected mechanisms as electron transport chain and energetic metabolism, ROS production and insufficiency of antioxidant defensive system could lead to induction of cell death.

Comparison of effects of some cyclic chalcone analogues on selected mitochondrial functions.

In earlier studies, cytotoxity of chalcones (1) and cyclic chalcone analogues E-2-arylidene-tetralones (2) and -benzosuberones (3) towards various murine and human tumour cells has been tested. Preliminary biochemical investigations showed the compounds to inhibit protein and DNA syntheses. It was also found that the compounds affect the cellular thiol status of the treated cells. In order to gain new insights into the cytotoxic mechanism of the compounds effects of some previously investigated 2 and 3 derivatives on isolated rat liver mitochondria was investigated. It was found that the most cytotoxic compounds 2c and 3b significantly decreased the GSH level of the mitochondria. Incubation of the investigated chalcones with reduced GSH under cell-free conditions indicated spontaneous conjugation (non-redox) reaction at pH 7.4 and pH 9.0. Investigation of antioxidant capacity of the compounds by monitoring time course of the Fenton-reaction initiated in vitro degradation of 2-deoxyribose showed the compounds to display hydroxyl radical scavenger activity. Investigation of respiratory control ratio of 2c and 3b showed the compounds to display an inhibitory effect on respiration, compound 2b, however, displayed rather an uncoupling effect. The experiments provide further details of cytotoxic effects of the synthetic chalcones displaying dual - cytotoxic and cytoprotective - effects.

Effect of quercetin on daunorubicin-induced heart mitochondria changes in rats.

Cancer therapy with daunorubicin is limited by its cardiotoxicity. It has been suggested that daunorubicin-induced free radical generation can be involved. The precise molecular mechanism of daunorubicin-induced cardiotoxicity is still not well understood but it is believed that mitochondria play an important role in this process. It has been reported that flavonoids with antioxidant properties may prevent anthracycline-induced cardiotoxicity. In this work, we investigated the effects of daunorubicin and quercetin on mitochondrial enzyme activities such as ATPase, glutathione peroxidase (GPx) and glutathione reductase (GR). Moreover, we also studied the changes of outer mitochondrial membrane using synchronous fluorescence spectra. The activity of ATPase and GR were significantly increased after daunorubicin application. Pretreatment with quercetin significantly alleviated this increase. On the other hand, GPx activity was significantly decreased and quercetin prevented this decrease. Treatment with quercetin alone had no significant effect on the enzyme activity studied. Quercetin also completely prevented daunorubicin-induced changes in fluorescence of the outer mitochondrial membrane. In conclusion, our data indicate that quercetin may be useful in mitigating daunorubicin-induced cardiotoxicity.

Humoral immune response after vaccination against influenza in patients with breast cancer.

The aim of this pilot study was to assess a humoral response to influenza vaccine in 9 women with breast cancer. In the epidemic season 1998/1999 the patients received a single 0.5-ml dose of split influenza vaccine (Vaxigrip, Pasteur Merieux). Humoral response was measured by the hemagglutinin inhibition test in sera collected before vaccination and 1 month after vaccination. All results were compared with a control group of 19 healthy vaccinated women. The mean 'fold' increases ranged from 12.0 to 22.2 in patients with breast cancer and from 10.5 to 29.2 in healthy women. After vaccination, protection rates ranged from 44.4% to 88.9% and 63.2% to 94.7%, respectively. Response rates were between 44.4% and 88.9% in women with cancer and between 63.2% and 78.9% in the control group. After vaccination, antihaemagglutinin antibody titers were significantly higher than the prevaccination titers. During the whole study there were no statistically significant differences in humoral response between patients with breast cancer and healthy women. The results of the present study clearly show that women with breast cancer, including those undergoing chemotherapy, were able to develop a good serological response to influenza vaccine.

[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.)

[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.