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E Ivancheva

Publications and source records attributed to E Ivancheva.

18 recordsLinked to original sources
PubMed1995

Lipid peroxidation and antioxidant enzyme activity in aspirin-treated rats.

1. Malondialdehyde formation and antioxidant enzyme activity after oral or intraperitoneal treatment of rats with various doses of aspirin was studied. 2. Aspirin, orally, had no effect on spontaneous, Fe(II)- or Fe(II)/ascorbate-induced malondialdehyde formation in liver homogenates; orally, ascorbate-induced malondialdehyde production was inhibited but only after 5-day treatment with 500 mg/kg aspirin; after intraperitoneal injection, the drug inhibited ascorbate- and Fe(II)/ascorbate-induced production of malondialdehyde. 3. Aspirin had no effect on malondialdehyde formation in erythrocytes, irrespective of the dose and route of drug administration. 4. Aspirin increased glutathione peroxidase activity in liver after 5-day treatment with an oral dose of 500 mg/kg and decreased enzyme activity in both liver and erythrocytes, 24 hr after a single injection of the same dose. 5. Aspirin, in vivo slightly affected lipid peroxidation and antioxidant enzyme activity.

Administration, Oral↗
PubMed1994

In vitro effects of aspirin on malondialdehyde formation and on activity of antioxidant and some metal-containing enzymes.

The in vitro effects of aspirin in different concentrations on malondialdehyde formation and on the activity of antioxidant and some metal-containing enzymes in rat liver homogenate and erythrocytes were studied. Aspirin showed a biphasic dependence on concentration: low concentrations (to 1.0 mM) stimulated the spontaneously formed malondialdehyde in the liver homogenate and the high concentration (5.0 mM) inhibited it; all aspirin concentrations tested had no effect on the liposomes; 5.0 mM aspirin inhibited the Fe(2+)-induced lipid peroxidation in the liver homogenate but had an opposite effect on the liposomes. Aspirin dose-dependently inhibited nitro-blue tetrazolium reduction and decreased deoxyribose degradation. The higher aspirin concentrations inhibited the activity of antioxidant and some metal-containing enzymes. It is suggested that these aspirin effects are determined by the aspirin-metal complexes formed rather than by aspirin itself.

Animals↗
PubMed1994

Lipid peroxidation and antioxidant enzymes in vanadate-treated rats.

Male Wistar rats received an aqueous solution of ammonium metavanadate (AMV) of 0.15 mg/V/ml concentration instead of water for 14 days. The erythrocyte count and haemoglobin level in blood were not changed; the haematocrit index was slightly increased. The spontaneous lipid peroxidation in kidney and liver homogenates was increased. The Fe(II)- or ascorbate-induced lipid peroxidation was more pronounced in the kidney than in the liver. No changes in lipid peroxidation were observed in erythrocytes after AMV treatment. The AMV treatment resulted in a decrease in the activity of the antioxidant enzymes, catalase and glutathione peroxidase in the kidney and liver; the cytosolic Cu,Zn-SOD and mitochondrial Mn-SOD were unchanged. The activity of the enzymes in blood was not changed. The results are discussed with a view to the participation of lipid peroxidation in vanadium toxicity.

Animals↗
PubMed1991

Vanadyl causes hydroxyl radical mediated degradation of deoxyribose.

Vanadyl caused a time- and dose-dependent degradation of deoxyribose to carbonyl products detectable with thiobarbituric acid. This process was inhibited by catalase, ethanol or HEPES; whereas superoxide dismutase was without effect. Vanadate did not substitute for vanadyl even in the presence of a source of O2- plus H2O2; but it did so in the presence of reductants such as thiols or NADH. It appears that hydrogen peroxide, generated by the autoxidation of vanadyl, is reduced by vanadyl to the hydroxyl radical; which, in turn, was responsible for the degradation of deoxyribose. A similar process might contribute to the toxic and pharmacological effects of vanadium salts.

Catalase↗
PubMed1989

Effects of vanadate on the oxidation of NADH by xanthine oxidase.

Vanadate (V(V)) stimulates the oxidation of NADH by xanthine oxidase and superoxide dismutase eliminates the effect of V(V). Paraquat stimulates both the oxidation of NADH by xanthine oxidase and the V(V) enhancement of that oxidation. Xanthine, which is a better substrate for xanthine oxidase than is NADH, causes a V(V)-dependent co-oxidation of NADH which is transient and eliminated by SOD. Urate inhibits the V(V)-stimulated oxidation of NADH by xanthine oxidase or by Rose Bengal plus light. Measurement of rates of both O2- production and V(V)-stimulated NADH oxidation showed that many molecules of NADH were oxidized per O2-. These chain lengths were an inverse function of overall reaction rate. Minimum chain lengths, calculated on the basis of 100% univalent reduction of O2 to O2-, were smaller than measured average chain lengths by a factor of five. All of these results are in accord with the view that V(V) does not directly affect the activity of the enzyme, but rather catalyzes the free radical chain oxidation of NADH by O2-. It was further shown that phosphate was not involved and that the active form of V(V) was orthovanadate, rather than decavanadate.

Animals↗
PubMed1988

Vanadyl- and vanadate-induced lipid peroxidation in mitochondria and in phosphatidylcholine suspensions.

Vanadyl (V(IV] was found to induce rapidly developing lipid peroxidation in intact and sonicated mitochondria as well as in phosphatidylcholine suspension. The ability of vanadate (V(V] to induce lipid peroxidation was much less pronounced compared to that of vanadyl. The peroxidative action of vanadate on phosphatidylcholine much increased in the presence of NADH and ascorbate. Preincubation of vanadate with glucose had the same effect. Vanadyl-induced lipid peroxidation was not essentially influenced by SOD, catalase and ethanol but was completely inhibited by butylated hydroxytoluene. All these effects of vanadyl and vanadate are thought to participate in the insulin-like and other biological actions of vanadium.

Animals↗
PubMed1988

Phosphatidylcholine peroxidation induced by Cu(II) and some Cu(II) complexes.

We established that Cu(II) and its complexes with aspirin, indomethacin and cimetidine produced lipid peroxidation in phosphatidylcholine suspension. Ionic copper was found to have the most pronounced effect, while the effect of the complexes depends on the ligand. Neither of the ligands exerted a prooxidative effect. NADH sharply increased the effects of Cu(II) and its complexes. In contrast, in the presence of ascorbate the prooxidative effect of Cu(II) and its complexes decreased. Cu(II) and its complexes strongly inhibited ascorbate-induced lipid peroxidation. Using antioxidant substances, enzymes and copper-chelating agents, we attempted to explain the observed effects of Cu(II) and its complexes.

Ascorbic Acid↗
PubMed1987

The hemolytic effect of copper complexes with different ligands.

The effect of Cu(II) and Cu(II) complexes/Cu(II)(cimetidine)2 Cu(II)(glycine) and Cu(II)(glycine)2/on the rat and human erythrocytes was studied. Time- and dose-dependence of the Cu(II) complexes-induced hemolysis, oxidation of hemoglobin and formation of precipitates of denaturated hemoglobin were established. The hemolytic effect of Cu(II)complexes was abolished by strong complexons of Cu(II) and by physiological concentrations of albumin and histidine. The hemolysis greatly decreased in the presence of chelator of Cu(I) and superoxide dismutase, which suggested oxi-reduction transitions and participation of superoxide in the process. The results are considered with the view to clarifying the differences in the stability and reaction ability of the different complexes, the possibility of their parenteral application.

Animals↗
PubMed1986

In vitro study of paraquat effects on malondialdehyde formation in thymus cells.

The present experiments have shown that paraquat enhanced both O2- production and oxidation of exogenous NADPH in thymus cells by NADPH-dependent enzyme system. The effects of paraquat on malondialdehyde formation were also NADPH-dependent and opposite in the absence and in the presence of ferrous ions: Paraquat inhibited the NADPH-dependent malondialdehyde formation in the absence of Fe2+; it activated this formation in the presence of Fe2+ and had no effect on the nonenzymic Fe2+- and Fe2+-ascorbate-stimulated lipid peroxidation. It is suggested that the activating effect of paraquat on the enzymic NADPH-dependent MDA formation in the presence of Fe2+ is due to the formation of a powerful oxidant product (FeO2)+ or to some Fe2+-paraquat radical complex, acting similarly to the ADP-chelated ferrous ions.

Adrenochrome↗
PubMed1985

Lipid peroxidation in liver mitochondria from copper-loaded rats.

The amount of phospholipids in liver mitochondria decreased after chronic alimentary copper-loading of rats (40 mg CuSO4 per rat per day in the course of two weeks), while 24 hours after a single intraperitoneal injection of copper (20 mg CuSO4 per kg body weight) it remained unchanged, notwithstanding that both copper treatments highly increased the copper level in mitochondria. Alimentary copper-loading led to a decrease in the relative proportions of the majority of unsaturated fatty acids in mitochondrial phospholipids. Both the spontaneous and Fe2+-induced formation of malonaldehyde were more enhanced in the mitochondria from the two experimental groups as compared to the controls.

Animals↗
PubMed1979

Ascorbate and Fe++-induced lipid peroxidation in liver mitochondria isolated from copper-deficient rats.

The effects of ascorbate and Fe++ on lipid peroxidation are compared in liver mitochondria isolated from control and copper-deficient rats. Spontaneous, Fe++- and ascorbate-induced formation of compounds reacting with the thiobarbituric acid (TBA) and the swelling in the mitochondria are studied as indicators of lipid peroxidation. The initial level of TBA-reacting compounds in freshly isolated copper-deficient mitochondria is higher than that in the control mitochonidria. Incubation at 20--22 degrees C for 60 min leads to a greater increase in the amount of the spontaneously formed TBA-reacting compounds in the copper-deficient mitochondria. Both the Fe++--ions and the ascorbate induce lipid peroxidation more intensively in the copper-deficient mitochondria than in the controls. The differences between the two types of mitochondria are manifested also with respect to the effect of antimycin A on the ascorbate-induced lipid peroxidation. The data obtained concerning a more enhanced spontaneous and induced lipid peroxidation in copper-deficient mitochondria are explained with the higher level of lipid peroxides, changes organization and fatty-acid composition of the membranes, and with lower activity of superoxide dismutase and catalase.

Animals↗
PubMed1979

Reduction of Cu2+ by isolated rat liver mitochondria.

The present work provided evidence that isolated rat liver mitochondria reduce the larger part of the added CU2+ and that the reduction is of important for copper accumulation in mitochondria. The process is rapid, energy-independent and affected by steric factors. Both mitochondrial thiols and cytochrome c could participate in the Cu2+-reduction. Blocking of these mitochondrial components decrease sharply but does not abolish the reduction ability of mitochondria. Copper ions undergoing reversible reduction and oxidation in the presence of cysteine and ferrocytochrome c lead to the formation of O2- and H2O2. Superoxide radicals arise only from reoxidation of Cu+.

Animals↗
PubMed1978

Cu2+-effects on mitochondrial resistance to sodium deoxycholate.

The effect of the preincubation of mitochondria with different doses of Cu2+ on the action of sodium deoxycholate (DOC) was studied. The amount of protein released from mitochondria upon their treatment with Cu2+ as an indice for the intactness of mitochondria was studied, too. On the account of Cu2+-influence on the level of mitochondrial SH groups Cu2+-effects on the action of DOC were compared with those of a thiol reagent p-chlormercuribenzoate (p-CMB). The results obtained show the following: Cu2+ in doses higher than 20 nmoles/mg protein induces conformational changes in mitochondrial membranes becoming more pronounced over 100 nmoles Cu2+/mg protein. These changes increase mitochondrial resistance to the action of DOC. Cu2+ in doses up to 100 nmoles/mg protein depending on the protein concentration of the suspension provokes a release of lower or higher amounts of protein from mitochondria. The higher resistance of mitochondria to DOC, as well as the release of protein from mitochondria after Cu2+-incubation are not due to mercaptide binding of SH groups as p-CMB does not affect these parameters.

Animals↗
PubMed1976

Effect of crataemon on the respiration of isolated mitochondria.

Crataemon is a drug containing the total mixture of flavonoids isolated from the leaves of Crataegus minogina. Crataemon causes activation and inhibition of the respiration of isolated liver and heart mitochondria, with different time and dose dependence and with different sensitivity to EDTA. The activating effect develops immediately, it is caused by small doses of crataemon, it is lacking in uncoupled mitochondria and completely abolished by EDTA. The inhibitory effect develops immediately or after the activation phase, it is caused by higher doses and the degree and the latency period depend on the dose. This effect is due to the action of crataemon on the flavoprotein-cytochrome c section of the electron transport chain. The inhibitory effect is partly abolished by EDTA. These effects are explained by the presence of at least two crataemon components: EDTA-sensitive and EDTA-insensitive. The EDTA-sensitive component is determined as a zinc-flavonoid complex. In small doses it uncouples oxidative phosphorylation, while large doses inhibit the electron transport between flavoprotein and cytochrome c. The EDTA-insensitive component causes only inhibition of the electron transport in the same part of the chain and manifests its effect in the higher doses.

Animals↗