Functional activity and morphology of isolated rat cardiac mitochondria under calcium overload. Effect of naringin.

The function of mitochondria as a regulator of myocyte calcium homeostasis has been extensively discussed. The aim of the present work was further clarification of the details of modulation of the functional activity of rat cardiac mitochondria by exogenous Ca2+ ions either in the absence or in the presence of the plant flavonoid naringin. Low free Ca2+ concentrations (40-250 nM) effectively inhibited the respiratory activity of heart mitochondria, remaining unaffected the efficacy of oxygen consumption. In the presence of high exogenous Ca2+ ion concentrations (Ca2+ free was 550 µM), we observed a dramatic increase in mitochondrial heterogeneity in size and electron density, which was related to calcium-induced opening of the mitochondrial permeability transition pores (MPTP) and membrane depolarization (Ca2+free ions were from 150 to 750 µM). Naringin partially prevented Ca2+-induced cardiac mitochondrial morphological transformations (200 µM) and dose-dependently inhibited the respiratory activity of mitochondria (10-75 µM) in the absence or in the presence of calcium ions. Our data suggest that naringin (75 µM) promoted membrane potential dissipation, diminishing the potential-dependent accumulation of calcium ions by mitochondria and inhibiting calcium-induced MPTP formation. The modulating effect of the flavonoid on Ca2+-induced mitochondria alterations may be attributed to the weak-acidic nature of the flavonoid and its protonophoric/ionophoric properties. Our results show that the sensitivity of rat heart mitochondria to Ca2+ ions was much lower in the case of MPTP opening and much higher in the case of respiration inhibition as compared to liver mitochondria.

In Vitro Study of Cytostatic Activity of Baicalin, Baicalein, and Chlorophyllipt on HeLa-v Cell Line.

Cytostatic activity of baicalin, baicalein, and neogalenical drug Chlorophyllipt was studied in vitro on HeLa-v cells. Standard samples of Eucalimin, baicalin, and baicalein, as well as Chlorophyllipt and paclitaxel (reference drug Taxacad) were used. The cell deaths were determined by MTT assay in a Multiskan FC microplate reader with incubator. The effective inhibition concentration (IC50) of the tested substances were: paclitaxel (4.0±0.4 µM)-baicalein (10.5±1.1 µM)-baicalin (16.5±1.7 µM)-sum of euglobals in Chlorophyllipt (24.1±2.5 µM). Chlorophyllipt was found to exhibit cytostatic activity. Cytostatic activity of baicalein, baicalin, and Chlorophyllipt was lower than cytostatic activity of the reference drug by 2.6, 4.1, and 6 times, respectively. The prospects of further evaluation of the synergetic effect of baicalin, baicalein, and chlorophyllipt used in combinations with different cytostatic agents for finding the most effective combination have been shown.

The flavonoids fisetin, apigenin, kaempferol, naringenin, naringin regulate respiratory activity and membrane potential of rat liver mitochondria and inhibit oxidative processes in erythrocytes.

Flavonoids, secondary plant metabolites, represent the most abundant heterogeneous group of phytochemicals. The aim of this study to compare antioxidant activity and regulatory properties of several representatives of different classes of flavonoids, fisetin, apigenin, kaempferol, naringenin, naringin, using liver mitochondria and erythrocytes as research objects. In the concentration range of 2.5-25 µM fisetin, apigenin, kaempferol, naringenin, and naringin dose-dependently prevented oxidative damage of erythrocytes induced by 700 µM tert-butyl hydroperoxide: accumulation of lipid peroxidation (LPO) products and oxidation of glutathione GSH. The IC50 values corresponding to the flavonoid concentration inhibiting the LPO process in erythrocyte membranes by 50%, were 3.9±0.8 µM in the case of fisetin, 6.5±1.6 µM in the case of kaempferol, 8.1±2.1 µM in the case of apigenin, 37.8±4.4 µM in the case of naringenin, and 64.7±8.6 µM in the case of naringin. The antioxidant effect of flavonoids was significantly higher in the membrane structures compared to the cytoplasm of cells. All flavonoids studied (10-50 µM) effectively inhibited the respiratory activity of isolated rat liver mitochondria and, with the exception of kaempferol, stimulated Ca²âº-induced dissipation of the mitochondrial membrane potential. Cyclosporine A and ruthenium red inhibited flavonoid-stimulated Ca²âº-dependent membrane depolarization, thus indicating that the mitochondrial calcium uniporter and the mitochondrial permeability transition pore opening were involved in the flavonoid effects. Flavonoids, as the redox-active compounds with antioxidant properties, are able to regulate mitochondrial potential and respiratory activity, and prevent mitochondrial oxidative stress. They can be considered as effective pharmacological agents or nutraceuticals.

Rat liver mitochondrial damage under acute or chronic carbon tetrachloride-induced intoxication: protection by melatonin and cranberry flavonoids.

In current societies, the risk of toxic liver damage has markedly increased. The aim of the present work was to carry out further research into the mechanism(s) of liver mitochondrial damage induced by acute (0.8 g/kg body weight, single injection) or chronic (1.6g/ kg body weight, 30 days, biweekly injections) carbon tetrachloride - induced intoxication and to evaluate the hepatoprotective potential of the antioxidant, melatonin, as well as succinate and cranberry flavonoids in rats. Acute intoxication resulted in considerable impairment of mitochondrial respiratory parameters in the liver. The activity of mitochondrial succinate dehydrogenase (complex II) decreased (by 25%, p<0.05). Short-term melatonin treatment (10 mg/kg, three times) of rats did not reduce the degree of toxic mitochondrial dysfunction but decreased the enhanced NO production. After 30-day chronic intoxication, no significant change in the respiratory activity of liver mitochondria was observed, despite marked changes in the redox-balance of mitochondria. The activities of the mitochondrial enzymes, succinate dehydrogenase and glutathione peroxidase, as well as that of cytoplasmic catalase in liver cells were inhibited significantly. Mitochondria isolated from the livers of the rats chronically treated with CCl4 displayed obvious irreversible impairments. Long-term melatonin administration (10 mg/kg, 30 days, daily) to chronically intoxicated rats diminished the toxic effects of CCl4, reducing elevated plasma activities of alanine aminotransferase and aspartate aminotransferase and bilirubin concentration, prevented accumulation of membrane lipid peroxidation products in rat liver and resulted in apparent preservation of the mitochondrial ultrastructure. The treatment of the animals by the complex of melatonin (10 mg/kg) plus succinate (50 mg/kg) plus cranberry flavonoids (7 mg/kg) was even more effective in prevention of toxic liver injury and liver mitochondria damage.

[Structural and functional changes in rat liver mitochondria under calcium ion loading in the absence and presence of flavonoids]. / Strukturnye i funktsional'nye izmeneniia mitokhondrii pecheni krys pri nagruzke ionami kal'tsiia v otsutstvie i v prisutstvii flavonoidov.

The aim of the present work was to elucidate the mechanisms of calcium ion-induced impairments of the ultrastructure and functional activity of isolated rat liver mitochondria in the absence and presence of a number of flavonoids in vitro. In the presence of exogenous Ca²âº (20-60 µM), mitochondrial heterogeneity in size and electron density markedly increased: most organelles demonstrated a swollen electron-light matrix, bigger size, elongated cristae and a reduced their number, a damaged native structure of the inner membrane up to its detachment, and some mitochondria showed a more electron-dense matrix (condensed mitochondria). The calcium-induced opening of the mitochondrial permeability transition pores (MPTP) resulted in the ultrastructural disturbances and in the effective inhibition of the respiratory activity of rat liver mitochondria. The flavonoids (10-25 µM) naringenin and catechin, dose-dependently inhibited the respiratory activity of mitochondria and stimulated the MPTP opening in the presence of Ca²âº ions. Since Ruthenium red, an inhibitor of the mitochondrial Ca²âº uniporter, effectively prevented Ca²âº-induced MPTP opening both in the absence and presence of flavonoids, we hypothesized that the effect of flavonoids on the MPTP opening could be mediated by stimulation of the Ca²âº uniporter.

Activity of platelet hemostasis in children with spinal deformities.

An increase of adhesion and aggregation functions of platelets in vivo and in vitro was detected in 5-6-year-old children with scoliosis. These disorders were caused by hyperproduction of von Willebrand's factor in the vascular wall and intensification of thromboxane production in blood platelets. Activation of thromboxane formation is the main cause of platelet hyperactivity in children with scoliosis. Correction of platelet hemostasis may include pathogenetically substantiated complex of therapeutic exercises, swimming, and massage.

Protective effects of N-acetyl-L-cysteine against acute carbon tetrachloride hepatotoxicity in rats.

In recent years, N-acetyl-L-cysteine (NAC) has been widely investigated as a potentially useful protective and antioxidative agent to be applied in many pathological states. The aim of the present work was further evaluation of the mechanisms of the NAC protective effect under carbon tetrachloride-induced acute liver injuries in rats. The rat treatment with CCl4 (4 g/kg, intragastrically) caused pronounced hepatolysis observed as an increase in blood plasma bilirubin levels and hepatic enzyme activities, which agreed with numerous previous observations. The rat intoxication was accompanied by an enhancement of membrane lipid peroxidation (1.4-fold) and protein oxidative damage (protein carbonyl group and mixed protein-glutathione disulphide formations) in the rat liver. The levels of nitric oxide in blood plasma and liver tissue significantly increased (5.3- and 1.5-fold, respectively) as blood plasma triacylglycerols decreased (1.6-fold). The NAC administration to control and intoxicated animals (three times at doses of 150 mg/kg) elevated low-molecular-weight thiols in the liver. The NAC administration under CCl4-induced intoxication prevented oxidative damage of liver cells, decreased membrane lipid peroxidation, protein carbonyls and mixed protein-glutathione disulphides formation, and partially normalized plasma triacylglycerols. At the same time the NAC treatment of intoxicated animals did not produce a marked decrease of the elevated levels of blood plasma ALT and AST activities and bilirubin. The in vitro exposure of human red blood cells to NAC increased the cellular low-molecular-weight thiol levels and retarded tert-butylhydroperoxide-induced cellular thiol depletion and membrane lipid peroxidation as well as effectively inhibited hypochlorous acid-induced erythrocyte lysis. Thus, NAC can replenish non-protein cellular thiols and protect membrane lipids and proteins due to its direct radical-scavenging properties, but it did not attenuate hepatotoxicity in the acute rat CCl4-intoxication model.

Melatonin directly scavenges free radicals generated in red blood cells and a cell-free system: chemiluminescence measurements and theoretical calculations.

Melatonin, a pineal secretory product, has properties of both direct and indirect powerful antioxidant. The aim of the present study was to compare the radical-scavenging, structural and electronic properties of melatonin and tryptophan, precursor of melatonin. Using the alkoxyl- and peroxyl radical-generating systems [the organic peroxide-treated human erythrocytes and a cell-free system containing the azo-initiator 2,2'-azobis(2-amidinopropane)dihydrochloride], we evaluated the radical-scavenging effects of melatonin and tryptophan. Melatonin rather than tryptophan at concentrations of 100-2000 microM markedly inhibited membrane lipid peroxidation in human erythrocytes treated with organic hydroperoxide as well as radical-induced generation of luminol-dependent chemiluminescence. The apparent Stern-Volmer constants for inhibition of membrane lipid peroxidation by melatonin and tryptophan were estimated to be (0.23+/-0.05) x 10(4) M(-1) and (0.02+/-0.005) x 10(4) M(-1), respectively. The apparent Stern-Volmer constants for inhibition of azo-initiator-derived peroxyl radical generation by melatonin and tryptophan were determined to be (0.42+/-0.05) x 10(4) M(-1) and (0.04+/-0.01) x 10(4) M(-1), respectively. The structural and electronic properties of melatonin and its precursor, tryptophan, were determined theoretically by performing semi-empirical and ab initio calculations. The high radical-scavenging properties of melatonin may be explained by the high surface area value and high dipole moment value. From the thermodynamic standpoint, based on our calculations, N(1)-acetyl-N(2)-formyl-5-methoxykynuramine (AFMK), was the most stable end oxidative product of melatonin.

Antioxidative enzyme and glutathione S-transferase activities in diabetic rats exposed to long-term ASA treatment.

Low-dose acetylsalicylic acid (ASA) treatment is a standard therapeutic approach in diabetes mellitus for prevention of long-term vascular complications. The aim of the present work was to investigate the effect of long-term ASA administration in experimental diabetes on activities of some liver enzymes: glutathione peroxidase (GSHPx), catalase, glucose-6-phosphate dehydrogenase (G6PDH) and glutathione S-transferase (GST). Blood glucose, glycated hemoglobin, as well as plasma ALT and AST activities increased in rats with streptozotocin-induced experimental diabetes. The long-term hyperglycemia resulted in decreased activities of GSHPx (by 26%), catalase (by 34%), GST (by 38%) and G6PDH (by 27%) in diabetic animals. We did not observe increased accumulation of membrane lipid peroxidation products or altered levels of reduced glutathione in livers. The linear correlation between blood glucose and glycated hemoglobin in diabetic animals was distorted upon ASA treatment, which was likely due to a chemical competition between nonenzymatic protein glycosylation and protein acetylation. The long-term ASA administration partially reversed the decrease in GSHPx activity, but did not influence the activities of catalase and GST in diabetic rats. Otherwise, some decrease in these parameters was noted in ASA-treated nondiabetic animals. Increased ASA-induced G6PDH activity was recorded in both diabetic and nondiabetic rats. While both glycation due to diabetic hyperglycemia and ASA-mediated acetylation had very similar effects on the activities of all studied enzymes but G6PDH, we conclude that non-enzymatic modification by either glucose or ASA may be a common mechanism of the observed convergence.

Anthropogenic- and natural sources of dust in peatland during the Anthropocene.

As human impact have been increasing strongly over the last decades, it is crucial to distinguish human-induced dust sources from natural ones in order to define the boundary of a newly proposed epoch - the Anthropocene. Here, we track anthropogenic signatures and natural geochemical anomalies in the Mukhrino peatland, Western Siberia. Human activity was recorded there from cal AD 1958 (±6). Anthropogenic spheroidal aluminosilicates clearly identify the beginning of industrial development and are proposed as a new indicator of the Anthropocene. In cal AD 1963 (±5), greatly elevated dust deposition and an increase in REE serve to show that the geochemistry of elements in the peat can be evidence of nuclear weapon testing; such constituted an enormous force blowing soil dust into the atmosphere. Among the natural dust sources, minor signals of dryness and of the Tunguska cosmic body (TCB) impact were noted. The TCB impact was indirectly confirmed by an unusual occurrence of mullite in the peat.

Membrane effects of nitrite-induced oxidation of human red blood cells.

The aim of our investigation was to study the red blood cell (RBC) membrane effects of NaNO(2)-induced oxidative stress. Hyperpolarization of erythrocyte membranes and an increase in membrane rigidity have been shown as a result of RBC oxidation by sodium nitrite. These membrane changes preceded reduced glutathione depletion and were observed simultaneously with methemoglobin (metHb) formation. Changes of the glutathione pool (total and reduced glutathione, and mixed protein-glutathione disulfides) during nitrite-induced erythrocyte oxidation have been demonstrated. The rates of intracellular oxyhemoglobin and GSH oxidation highly increased as pH decreased in the range of 7.5-6.5. The activation energy of intracellular metHb formation obtained from the temperature dependence of the rate of HbO(2) oxidation in RBC was equal to 16.7+/-1.6 kJ/mol in comparison with 12.8+/-1.5 kJ/mol calculated for metHb formation in hemolysates. It was found that anion exchange protein (band 3 protein) of the erythrocyte membrane does not participate significantly in the transport of nitrite ions into the erythrocytes as band 3 inhibitors (DIDS, SITS) did not decrease the intracellular HbO(2) oxidation by extracellular nitrite.

Hypochlorous acid damages erythrocyte membrane proteins and alters lipid bilayer structure and fluidity.

Treatment of human erythrocyte membranes with active forms of chlorine (hypochlorous acid and chloramine T) resulted in a concentration-dependent inhibition of the membrane Na(+), K(+)- and Mg(2+)-ATPases. Membrane protein thiol group oxidation was consistent with inactivation of enzymes and preceded oxidation of tryptophan residues and chloramine formation. Erythrocyte exposure to hypochlorous acid led to complex changes of cell membrane rigidity and cell morphological transformations: cell swelling, echinocyte formation, and haemolysis. The inhibition of ion pump ATPases of human erythrocyte membranes may be due to direct oxidation of essential residues of enzyme (thiol groups) and structural rearrangement of the membrane.

[Study of heat denaturation of human serum albumin in water-alcohol and water-salt solutions in the presence of organic ligands]. / Issledovanie teplovoi denaturatsii syvorotochnogo al'bumina cheloveka v vodno-spirtovykh i vodno-solovykh rastvorakh v prisutstvii organicheskikh ligandov.

The method of differential scanning microcalorimetry was used to show a decrease in heat stability of serum albumin in the presence of aliphatic alcohols. In aqueous-alcohol media, the melting temperature, denaturation transition enthalpy were decreased, and the protein intermolecular aggregation enhanced. When the alcohol concentration in aqueous solution was elevated, the number of epsilon-amino groups of lysine residues in human serum albumin exposed to the solvent rose from 6-7 in aqueous solution to maximum 20 groups in the aqueous-alcohol solution, respectively. The elevation of ionic strength also induced an increase in the number of exposed lysine residues and was accompanied by an enhancement of protein aggregation. The modification of six amino groups by pyridoxal phosphate or three by glucose in the initial albumin stabilized the protein incubated at 65 degrees-70 degrees C both in the aqueous-alcohol media. At the given concentration and temperature the native protein was denatured and fully aggregated. Aliphatic alcohols displaced fatty acids from the binding sites on the molecule of serum albumin, which resulted in a change in the number of peaks of the melting curve.

[Thermal stability and functional properties of human hemoglobin in the presence of aliphatic alcohols]. / Termostabil'nost' i funktsional'nye svoistva gemoglobina cheloveka v prisutstvii alifaticheskikh spirtov.

Differential scanning microcalorimetry was used to study thermal stability of the ferro- and ferriforms of hemoglobin at pH 7.4 in phosphate buffer and in buffer mixtures of methanol, ethanol, 1-propanol. Denaturation of the human hemoglobin molecule composed of four subunits was cooperative transition. The thermostability of the hemoglobin forms decreased in the order of carboxyhemoglobin (TD = 82.0 degrees C) > oxyhemoglobin (71.0 degrees C) > methemoglobin (67.0 degrees C). The aliphatic alcohols as cosolvents decreased the hemoglobin stability because of loosening the structure of the globin moiety by disturbing its hydrophobic contacts and hydrogen bonds. These alcohols reduced the oxygen affinity for hemoglobin probably due to perturbation of the R<-->T equilibrium by the decreased bulk dielectric constant of the solvent. Oxyhemoglobin and methemoglobin was converted to hemichrome by high alcohol concentrations.

[Parameters of interaction of sodium dodecyl sulfate with human hemoglobin]. / Parametry vzaimodeistviia dodetsilsul'fata natriia s gemoglobinom cheloveka.

It was shown that sodium dodecyl sulfate at concentrations not exceeding the critical micelle concentrations (0-1.9 mM) induced the conversion of oxy- and methemoglobin but not deoxyhemoglobin to hemichrome. The concentration dependences of hemichrome formation were represented as Hill plots, and the parameters of detergent binding were estimated. OxyHb in 20 mM potassium-phosphate buffer, pH 6.8, has two groups of binding sites: the first group is characterized by the Hill constant n1 = 2 and the concentration of half saturation [SDS]50 = 0.8 mM, and the second group is characterized by the Hill constant n2 = 8 and [SDS]50 = 0.9 mM. In the case of metHb one group of binding sites with the Hill constant n = 2 and half saturation concentration [SDS]50 = 0.2 mM was observed. An increase in environmental pH to 7.9 decreased the affinity of Hb for SDS. It is suggested that primary binding sites for SDS in oxyHb coincide with the anion-binding center of the Hb molecule. The interaction of the detergent with these binding sites induced a structural transition of the hemoprotein molecule. As a result of this transition, secondary binding sites were exposed. In a model system (hemin--imidazole in ethanol solution), the enthalpy of the transition of hemin from a high-spin to a low-spin state was estimated to be 47 +/- 7 kJ/mol.

[Thermal stability of erythrocyte membrane proteins at varying ionic strength and media composition]. / Termostabil'nost' belkov éritrotsitarnykh membran pri var'irovanii ionnoi sily i sostava sredy.

Varying the ionic strength and environmental composition differently affected the thermostability of certain protein blocks in the erythrocyte membrane. As the salt concentration in the solution enhanced, the redistribution of the system of intra- and intermolecular noncovalent bonds occurred, which induced changes in the membrane proteins structure resulting in an increase in the thermostability of both the integral and cytoplasmic band 3 domains and its associated band 4.2. The thermostability of the skeleton junction proteins (actin, 4.1 and 4.9) decreased. The thermostability of the spectrin changed insignificantly. The interaction of Mg2+ and Cu2+; but not Ca2+ ions with the membrane resulted in dynamic quenching the tryptophan fluorescence of the membrane proteins, unchanging their thermostability. Ca2+ ions induced the aggregation of erythrocyte membranes with increasing the temperature.

[Effect of the volumetric dielectric properties of the medium on stability of the globular proteins and membranes]. / Vliianie ob''emnykh diélektricheskikh svoistv sredy na stabil'nost' globuliarnykh belkov i membran.

Analysis of the temperature dependences of the denaturation enthalpy of three domains of albumin molecule showed significant distinctions in the destabilizing effect of ethanol on certain domains of the nondefatted and defatted albumin molecules. A linear relationships were found among the parameters of proteins and membranes stability and bulk dielectric constants of the solvents. It has been suggested that the dielectric characteristics of the medium play a significant role in the maintaining of the certain conformation of proteins and membranes.

[Thermostability of erythrocyte membranes in the presence of ethanol]. / Termostabil'nost' éritrotsitarnykh membran v prisutstvii étanola.

Differential scanning microcalorimetry was used to show a destabilizing effect of ethanol on erythrocyte membrane proteins. The thermostability of the membrane cooperative unit, with the main protein being band 3 integral protein, was decreased most significantly, which was probably related to a disturbance in protein--lipid complementary. At sufficiently high ethanol concentrations the denaturational changes in the membrane proteins resulted in lysis of red blood cells preceeding at several stages: morphological changes in cells, as well as swelling and the lysis, proper. The activation energy of the ethanol-induced lysis as determined from the temperature dependence of the apparent hemolysis rate constant was equal to 150 +/- 20 kJmol-1 at 5.1 M ethanol concentration. This corresponded to the activation energy of the protein denaturation.

[Methanotrophic bacteria in cold seeps of the floodplains of northern rivers].

Small mud volcanoes (cold seeps), which are common in the floodplains of northern rivers, are a potentially important, although poorly studied sources of atmospheric methane. Field research on the cold seeps of the Mukhrina River (Khanty-Mansiysk Autonomous okrug, Russia) revealed methane fluxes from these structures to be orders of magnitude higher than from equivalent areas of the mid-taiga bogs. Microbial communities developing around the seeps were formed under conditions of high methane concentrations, low temperatures (3-5 degrees C), and near-neutral pH. Molecular identification of methane-oxidizing bacteria from this community by analysis of the pmoA gene encoding particulate methane monooxygenase revealed both type I and type II methanotrophs (classes Gammaproteobacteria and Alphaproteobacteria, respectively), with predomination of type I methanotrophs. Among the latter, microorganisms related to Methylobacterpsychrophilus and Methylobacter tundripaludum, Crenothrix polyspora (a stagnant water dweller), and a number of methanotrophs belonging to unknown taxa were detected. Growth characteristics of two isolates were determined. Methylobactersp. CMS7 exhibited active growth at 4-10 degrees C, while Methylocystis sp. SB12 grew better at 20 degrees C. Experimental results confirmed the major role ofmethanotrophic gammaproteobacteria in controlling the methane emission from cold river seeps.

Melatonin and succinate reduce rat liver mitochondrial dysfunction in diabetes.

Mitochondrial dysfunction and an increase in mitochondrial reactive oxygen species in response to hyperglycemia during diabetes lead to pathological consequences of hyperglycemia. The aim of the present work was to investigate the role of a specific functional damage in rat liver mitochondria during diabetes as well as to evaluate the possibility of metabolic and antioxidative correction of mitochondrial disorders by pharmacological doses of succinate and melatonin. In rat liver mitochondria, streptozotocin-induced diabetes was accompanied by marked impairments of metabolism: we observed a significant activation of α-ketoglutarate dehydrogenase (by 60%, p<0.05) and a damage of the respiratory function. In diabetic animals, melatonin (10 mg/kg b.w., 30 days) or succinate (50 mg/kg b.w., 30 days) reversed the oxygen consumption rate V(3) and the acceptor control ratio to those in nondiabetic animals. Melatonin enhanced the inhibited activity of catalase in the cytoplasm of liver cells and prevented mitochondrial glutathione-S-transferase inhibition while succinate administration prevented α-ketoglutarate dehydrogenase activation. The mitochondria dysfunction associated with diabetes was partially remedied by succinate or melatonin administration. Thus, these molecules may have benefits for the treatment of diabetes. The protective mechanism may be related to improvements in mitochondrial physiology and the antioxidative status of cells.