Release Of Superoxide Radicals Research Articles

Single-route delaminated clay composites for efficient visible-light photo-mineralization of antibiotic-resistant bacteria and associated genes in water

Drinking water contaminated with antibiotic resistant bacteria could result in loss of antibiotic effectiveness in humans, increased healthcare cost and ultimately death. New delaminated photocatalytic composite (DPC) has been prepared. DPC doped with Cu/Zn kept multidrug resistant (MDR) E. coli and its sulphonamide resistance genes in contaminated water at log reduction >6 for 36 h in two disinfection steps under visible-light using fixed-bed mode (downward flow). In contrast, fluoroquinolone resistance genes persisted in treated water after the first disinfection step and were significantly reduced after the second disinfection step. Surface oxygen vacancies were mainly responsible for photoactivity of DPC. No bacteria re-growth was observed in treated water stored in light/dark for 7 days. A 95 % photo-mineralisation of MDR E. coli and its genes was achieved via the release of superoxide radical (in dark/light). Shelf-life study of DPC vs non-delaminated photocatalytic composite over 7 months suggests that the former remained far more efficient than the latter.

Penetration, distribution and brain toxicity of titanium nanoparticles in rodents' body: a review.

Titanium dioxide (TiO2) has been vastly used commercially, especially as white pigment in paints, colorants, plastics, coatings, cosmetics. Certain industrial uses TiO2 in diameter <100 nm. There are three common exposure routes for TiO2: (i) inhalation exposure, (ii) exposure via gastrointestinal tract, (iii) dermal exposure. Inhalation and gastrointestinal exposure appear to be the most probable ways of exposure, although nanoparticle (NP) penetration is limited. However, the penetration rate may increase substantially when the tissue is impaired. When TiO2 NPs migrate into the circulatory system, they can be distributed into all tissues including brain. In brain, TiO2 lead to oxidative stress mediated by the microglia phagocytic cells which respond to TiO2 NPs by the production and release of superoxide radicals that convert to multiple reactive oxygen species (ROS). The ROS production may also cause the damage of blood-brain barrier which then becomes more permeable for NPs. Moreover, several studies have showed neuron degradation and the impairment of spatial recognition memory and learning abilities in laboratory rodent exposed to TiO2 NPs.

CGMP-Phosphodiesterase Inhibition Prevents Hypoxia-Induced Cell Death Activation in Porcine Retinal Explants.

Retinal hypoxia and oxidative stress are involved in several retinal degenerations including diabetic retinopathy, glaucoma, central retinal artery occlusion, or retinopathy of prematurity. The second messenger cyclic guanosine monophosphate (cGMP) has been reported to be protective for neuronal cells under several pathological conditions including ischemia/hypoxia. The purpose of this study was to evaluate whether the accumulation of cGMP through the pharmacological inhibition of phosphodiesterase (PDE) with Zaprinast prevented retinal degeneration induced by mild hypoxia in cultures of porcine retina. Exposure to mild hypoxia (5% O2) for 24h reduced cGMP content and induced retinal degeneration by caspase dependent and independent (PARP activation) mechanisms. Hypoxia also produced a redox imbalance reducing antioxidant response (superoxide dismutase and catalase activities) and increasing superoxide free radical release. Zaprinast reduced mild hypoxia-induced cell death through inhibition of caspase-3 or PARP activation depending on the cell layer. PDE inhibition also ameliorated the effects of mild hypoxia on antioxidant response and the release of superoxide radical in the photoreceptor layer. The use of a PKG inhibitor, KT5823, suggested that cGMP-PKG pathway is involved in cell survival and antioxidant response. The inhibition of PDE, therefore, could be useful for reducing retinal degeneration under hypoxic/ischemic conditions.

Real-time investigation of antibiotics-induced oxidative stress and superoxide release in bacteria using an electrochemical biosensor

The involvement of oxidative stress in the mechanism of antibiotics-meditated cell death is unclear and subject to debate. The kinetic profile and a quantitative relationship between the release of reactive oxygen species (ROS), bacteria and antibiotic type remain elusive. Here we report direct measurements and analytical quantification of the release of superoxide radicals (O2·−), a major contributor to ROS, in antibiotics-treated bacterial cultures using a cytochrome c electrochemical biosensor. The specificity of electrochemical measurements was established by the addition of superoxide dismutase (SOD) which decreased the O2·− signal. Measurements using a general ROS-specific fluorescence dye and colony forming units (CFU) assays were performed side-by-side to determine the total ROS and establish the relationship between ROS and the degree of lethality. Exposure of Escherichia coli and Listeria monocytogenes cultures to antibiotics increased the release of O2·− radicals in a dose-dependent manner, suggesting that the transmembrane generation of ROS may occur as part of the antibiotic action. The study provides a quantitative methodology and fundamental knowledge to further explore the role of oxidative stress in antibiotics-meditated bacterial death and to assess physiological changes associated with the complex metabolic events related to oxidative stress and bacterial resistance.

Superoxide microsensor integrated into a Sensing Cell Culture Flask microsystem using direct oxidation for cell culture application

A new electrochemical sensor system for reliable and continuous detection of superoxide radical release from cell culture was developed utilizing direct oxidation of superoxide on polymer covered gold microelectrodes. Direct superoxide oxidation was demonstrated to provide robust measurement principle for sensitive and selective reactive oxygen species (ROS) quantification without the need for biocomponent supported conversion. Sensor performance was investigated by using artificial enzymatic superoxide production revealing a sensitivity of 2235AM−1m−2. An electrode protection layer with molecular weight cut-off property from adsorbed linear branched polyethylenimine was successfully introduced for long term and selectivity improvement. Thin-film based sensor chip fabrication with implemented three-electrode setup and full integration into the technological platform Sensing Cell Culture Flask was described. Cell culturing directly on-chip and free radical release by phorbol-12-myristate-13-acetate (PMA) stimulation was demonstrated using T-47D human breast cancer carcinoma cell model. Transient extracellular superoxide production upon stimulation was successfully observed from amperometric monitoring. Signal inhibition from scavenging of extracellular superoxide by specific superoxide dismutase (SOD) showed the applicability for selective in vitro ROS determination. The results confirm the possibility of direct superoxide oxidation, with exclusion of the main interfering substances uric acid and hydrogen peroxide. This offers new insights into the development of reliable and robust ROS sensors.

The antioxidant effects of thymoquinone in lipopolysaccharide‐activated BV2 murine microglia cells (89.5)

Activation of microglia, resident immune cells in the central nervous system (CNS), is implicated in the pathogenesis and progression of neurodegenerative disorders such as Alzheimer’s and Parkinson’s disease. They may cause a vicious self‐perpetuating neuronal degeneration cycle via excessive release of superoxide radicals in the system. We explored the effects of thymoquinone (TQ), the main active constituent of Nigella sativa seed oil, as an antioxidant agent in microglial activation. We hypothesized that the antioxidant properties of TQ are mediated in part by reducing proteins involved in oxidative stress induced by microglia activation. In this study, BV2 cells were stimulated with LPS in the presence or absence of TQ. To profile the effect of TQ on global protein expression of BV2 microglial cells, two‐dimensional (2D)‐gel electrophoresis with MALDI‐TOF/TOF (matrix‐assisted laser desorption/ionization ‐ time of flight) analysis was employed. Additionally, the effect of TQ on microglia activation was evaluated using immunocytochemistry‐ immunofluorescence (ICC‐IF). The results obtained indicate that TQ decreased the expression of 60 kDa heat shock, fatty acid binding, and CD68 [ED1] proteins in LPS stimulated BV2 cells. These findings suggest that the intervention of microglial activation process could be a promising therapeutic target in the treatment of a number of neurodegenerative conditions.Grant Funding Source: Supported by NIH grants: NIMHD G12 MD007582 and P20 MD006738

Activation of H2O2 and superoxide production using a novel cobalt complex based on a polyampholyte

A new catalyst based on Co(II) and a hydrogel with property of polyampholyte was characterized by equilibrium studies of Co(II) uptake, solid-state NMR and energy dispersive X-ray analysis. The matrix derived from methacrylic acid and 2-methylimidazole is easily synthesized in one-spot strategy, and combines coordination properties with chemical resistance. The catalytic activity of this material on H2O2 activation was studied by electron spin resonance, which confirmed the release of superoxide radical. A possible mechanism of interaction involves the simultaneous production of dioxygen, protons and water. The catalytic performance was assessed in the activation of H2O2 for the oxidation of two representative organic compounds of environmental concern. About 70% of methyl orange, a model azo dye, was removed from distilled water in 2h by oxidation with H2O2 60mM and by adsorption on the catalyst. The amount of adsorbed dye was minimized in the presence of 0.1M Na2SO4. The kinetics of the processes followed a pseudo-first-order empirical model, and the catalyst was recovered and re-used. Epinephrine was chosen as a pharmaceutical model susceptible to superoxide attack. About 80% of conversion to adrenochrome was reached in less than 6min, following a pseudo-first-order kinetic model.

Effects of environmental stresses on the responses of mangrove plants to spent lubricating oil

The influence of different environmental stresses, including salinity (5–35‰), tidal cycle (6/6, 12/12 and 24/24h of high/low tidal regimes) and nutrient addition (1–6 times background nitrogen and phosphorus content) on Bruguiera gymnorrhiza and Aegiceras corniculatum grown in sediment contaminated with spent lubricating oil (7.5Lm−2) were investigated. The oil-treated 1-year-old mangrove seedlings subject to low (5‰) and high (35‰) salinity had significantly more reduction in growth, more release of superoxide radical (O2−) and higher activity of superoxide dismutase (SOD) than those subject to moderate salinity (15‰). Extended flooding (24/24h of high/low tidal regime) enhanced O2− release and malondialdehyde (MDA) content in both oil-treated species but had little negative effects on biomass production (P>0.05) except the stem of A. corniculatum (P=0.012). The addition of nutrients had no beneficial or even posed harmful effects on the growth and cellular responses of the oil-treated seedlings.

Lucigenin- and Luminol-Dependent Chemiluminescence of Blood Neutrophils in Patients with Renal Cancer

High basal production of primary active oxygen forms was detected in the peripheral blood neutrophils of patients with renal cell cancer. In vitro stimulation of neutrophils led to more rapid release of superoxide radicals into extracellular space and to a reduction of cell capacity to more intense production of primary active oxygen forms.

Oxidative Damage of Mitochondrial Proteins Contributes to Fruit Senescence: A Redox Proteomics Analysis

Oxidative damage to mitochondria caused by reactive oxygen species (ROS) has been implicated in the process of senescence as well as a number of senescence-related disorders in a variety of organisms. Whereas mitochondrial DNA was shown to be oxidatively modified during cellular senescence, mitochondrial protein oxidation is not well-understood. With the use of high-resolution, two-dimensional gel electrophoresis coupled with immunoblotting, we show here that protein carbonylation, a widely used marker of protein oxidation, increased in mitochondria during the senescence of peach fruit. Specific mitochondrial proteins including outer membrane transporter (voltage-dependent anion-selective channel, VDAC), tricarboxylic acid cycle enzymes (malate dehydrogenase and aconitase), and antioxidant proteins (manganese superoxide dismutase, MnSOD) were found as the targets. The oxidative modification was concomitant with a change of VDAC function and loss of catalytic activity of malate dehydrogenase and MnSOD, which in turn facilitated the release of superoxide radicals in mitochondria. Reduction of ROS content by lowering the environmental temperature prevented the accumulation of protein carbonylation in mitochondria and retarded fruit senescence, whereas treatment of fruit with H2O2 had the opposite effect. Our data suggest that oxidative damage of specific mitochondrial proteins may be responsible for impairment of mitochondrial function, thus, leading to fruit senescence. Proteomics analysis of mitochondrial redox proteins provides considerable information on the molecular mechanisms involved in the progression of fruit senescence.

Marchantiophyta and inedible mushrooms: marvelous sources of bioactive molecules

The biological activity ascribed to the Marchantiophyta is due mainly to sesqui- and diterpenoids and phenolic compounds. Novel terpenoids, phenolics and acetogenins showing characteristic scent, hot-taste, allergenic contact dermatitis, cytotoxicity, insect antifeedant, anti-HIV, superoxide radical release inhibitory, antimicrobial, antifungal, muscle relaxing, apoptosis inducing activity against HL-60, NO production inhibitory activity, liver X receptors agonist/antagonist activity have been isolated from the Marchantiophyta (Blasiaceae, Frullaniaceae, Jungermanniaceae, Lejeuneaceae, Marchantiaceae, Pelliaceae, Plagiochialceae, Porellaceae and Aytoniaceae) species. The chemical constituents of 24 inedible mushroom species belonging to five families, Scutigeraceae, Polypolaceae, Xylariaceae, Thelephoraceae and Paxillaceae were studied. Various type of chemical substances including p-terphenyls, cytochalacines, pregnanes, azaphilones, binaphthyls, lanostanes, 3(R)-hydroxybutyric acid, its dimmer and trimer which showed a broad activity of in many biological systems, such as antimicrobial, antinematicidal, NO production and TNF-α release inhibitory activity, anti-HIV, anti-HSV and antioxidant activities were isolated and their structures characterized.

Effects of melatonin on plasma oxidative stress in rats with streptozotocin induced diabetes

The aim of this study was to evaluate the effect of single melatonin injection on plasma oxidative stress in rats with streptozotocin induced diabetes. Diabetes was induced after a single intraperitoneal dose of streptozotocin (60 mg/kg), while hyperglycemia was determined 10 days upon injection. Diabetic rats were divided into two groups. In the first group the injection of melatonin was applied intraperitoneally (20 mg/kg), while the second group received physiological solution. Twenty-four hours later the rats were killed and their blood was centrifuged. In the rat plasma the following parameters were evaluated: the glucose level, superoxide radical, lipid peroxidation, reduced glutathione, total antioxidant capacity, antioxidant enzymes and the aldose reductase activity. The injected melatonin decreased the superoxide radical in the rat plasma. Moreover, melatonin increased the total antioxidative capacity and the activity of antioxidative enzymes superoxide dismutase and glutathione peroxidase. These results indicate that melatonin is a strong scavenger, which may diminish negative effects of oxidative stress in diabetic rats 24 hours after its application The findings suggest that melatonin is also a strong antioxidant. It increases the antioxidant enzymes activity, inhibiting the release of superoxide radicals. A high total antioxidative capacity and the lower activity of aldose reductase enlarge melatonin scavenger capacity against reactive oxygen species in diabetic rats.

Inhibition of diet-induced atherosclerosis and endothelial dysfunction in apolipoprotein E/angiotensin II type 1A receptor double-knockout mice.

Angiotensin II type 1 (AT1) receptor activation is potentially involved in the multifactorial pathogenesis of atherosclerosis. Apolipoprotein E-deficient (ApoE-/-) mice were crossed with AT1A receptor-deficient (AT1-/-) mice to obtain homozygous double-knockout animals (ApoE-/--AT1-/- mice). Wild-type (C57BL/6J), ApoE-/-, AT1-/-, and ApoE-/--AT1-/- mice were fed a high-cholesterol diet for 7 weeks. In contrast to wild-type and AT1-/- mice, this treatment led to severe atherosclerotic lesion formation in the aortic sinus and the aorta (oil red O staining) and to an impaired endothelium-dependent vasodilation (organ chamber experiments with isolated aortic segments) in ApoE-/- mice. In the age-matched ApoE-/--AT1-/- littermates, development of diet-induced endothelial dysfunction and atherosclerotic lesion formation was profoundly inhibited. Concomitantly, aortic release of superoxide radicals was increased 2-fold in ApoE-/- mice compared with wild-type animals, whereas aortic superoxide production was normalized in ApoE-/--AT1-/- mice (L-012 chemiluminescence). There were no significant differences in plasma cholesterol levels between ApoE-/- and ApoE-/--AT1-/- animals. Systolic blood pressure was significantly lower in ApoE-/--AT1-/- animals than in ApoE-/- mice (tail-cuff measurements). Oral treatment of ApoE-/- mice with either hydralazine or irbesartan reduced systolic blood pressure to the same level; however, only AT1 receptor antagonist treatment reduced atherosclerotic lesion formation and improved endothelial function. Genetic disruption of the AT1A receptor leads to inhibition of vascular oxidative stress, endothelial dysfunction, and atherosclerotic lesion formation in ApoE-/- mice irrespective of blood pressure and plasma cholesterol levels. These results indicate a fundamental role of AT1 receptor activation in atherogenesis.

Impaired superoxide radical production by bronchoalveolar lavage cells from NO 2-exposed rats

Production of superoxide radicals is a central property of professional phagocytes used to combat invading microorganisms. Even though the number of macrophages and neutrophils is often increased in the lungs of patients with chronic lung diseases, these patients frequently suffer from bacterially induced exacerbations. To understand the underlying mechanisms, we investigated the production of superoxide radicals by bronchoalveolar lavage (BAL) cells in a rat NO 2 exposure model (10 ppm NO 2 for 1, 3, or 20 days). We showed that cells from NO 2-exposed animals display a significantly impaired superoxide radical release after zymosan stimulation. The use of specific inhibitors (antimycin or diphenyleneiodonium [DPI]) revealed that the major enzyme systems, NADPH oxidase and complex III of the respiratory chain, are affected. In addition, we investigated gene expression and enzyme activities of antioxidant enzymes. mRNA expression was significantly enhanced for glutathione peroxidase (GPx)-3 and CuZn-superoxide dismutase (SOD) in BAL cells from animals exposed 3 and 20 days, and GPx and SOD enzyme activities were increased in BAL cells from rats exposed 20 days. In conclusion, concomitant occurrence of reduced production and increased scavenging of superoxide radicals resulted in the drastically impaired release of these radicals from BAL cells of NO 2-exposed rats.

Role of K + channels in the coronary and renal vascular reactivity to vasopressin in diabetic rats

To study the role of K + channels in the coronary and renal vascular response to vasopressin during diabetes mellitus, and whether there are gender differences in this role, we have examined the isometric response to this peptide of 2-mm-long arterial segments from male and female, normoglycemic and streptozotocin-induced diabetic rats. Vasopressin (10 −12–3×10 −8 M) produced arterial concentration-dependent contraction, and during normoglycemia, this contraction was lower in coronary arteries from female than from male rats, and it was similar in renal arteries from both genders. This contraction was reduced by diabetes in coronary arteries, and increased in renal arteries, from both genders. The blocker of Ca 2+-sensitive K + channels charybdotoxin (10 −7 M) increased the contraction to vasopressin in coronary arteries of diabetic females, but not in the other cases (diabetic males and normoglycemic females or males). This blocker also increased the contraction to vasopressin in renal arteries from diabetic, but not in those from normoglycemic female rats, and also increased it in a higher magnitude in arteries from diabetic than in those from normoglycemic male rats. The blocker of ATP-sensitive K + channels glybenclamide (10 −5 M) or the scavenger of superoxide radicals superoxide dismutase (100 U/ml) did not modify the contraction to vasopressin in any experimental group. These results suggest that diabetes activates the modulatory role of K + channels in the coronary and renal vasoconstriction to vasopressin, but it alters in a different way the vasoconstriction to vasopressin in these two types of arteries. The effects of diabetes on this vasoconstriction are not related to increased release of superoxide radicals.

Mitochondrial Superoxide Radical Formation is Controlled by Electron Bifurcation to the High and Low Potential Pathways

The generation of oxygen radicals in biological systems and their sites of intracellular release have been subject of numerous studies in the last decades. Based on these studies mitochondria are considered to be the major source of intracellular oxygen radicals. Although this finding is more or less accepted, the mechanism of univalent oxygen reduction in mitochondria is still obscure. One of the most critical electron transfer steps in the respiratory chain is the electron bifurcation at the cytochrome bc 1 complex. Recent studies with genetically mutated mitochondria have made it clear that electron bifurcation from ubiquinol to the cytochrome bc 1 complex requires the free mobility of the head domain of the Rieske iron-sulfur protein. On the other hand, it has been long known that inhibition of electron bifurcation by antimycin A causes leakage of single electrons to dioxygen, which results in the release of superoxide radicals. These findings lead us to study whether hindrance of the interaction of ubiquinol with the cytochrome bc 1 complex is the regulator of single electron diversion to oxygen. Hindrance of electron bifurcation was observed following alterations of the physical state of membrane phospholipids in which the cytochrome bc 1 complex is inserted. Irrespective of whether the fluidity of the membrane lipids was elevated or decreased, electron flow rates to the Rieske iron-sulfur protein were drastically reduced. Concomitantly superoxide radicals were released from these mitochondria, strongly suggesting an effect on the mobility of the head domain of the Rieske iron-sulfur protein. This revealed the involvement of the ubiquinol cytochrome bc 1 redox couple in mitochondrial superoxide formation. The regulator, which controls leakage of electrons to oxygen, appears to be the electron-branching activity of the cytochrome bc 1 complex.

Astrocytes rather than neurones mediate interleukin-1β dependent nitric oxide and superoxide radical release in primary hypothalamic rat cell cultures

The cellular sources of nitric oxide in the hypothalamus are thought to be ‘NOergic’ neurones. Using free radical electrochemical sensors we investigated nitric oxide and superoxide radical release in primary hypothalamic cell cultures. We present evidence that under interleukin-1β (IL-1β) stimulation hypothalamic astrocytes rather than neurones release nitric oxide. Under l-arginine deprivation and IL-1β stimulation a concentration-dependent release of superoxide was also observed, which was inhibited in the presence of nitric oxide synthase inhibitor nitro- l-arginine-methyl-ester. These findings support the hypothesis that the balance between nitric oxide and superoxide may be of vital importance in hypothalamic pathophysiology.

Dietary l-arginine and α-tocopherol reduce vascular oxidative stress and preserve endothelial function in hypercholesterolemic rabbits via different mechanisms

Vascular oxidative stress brought about by superoxide radicals and oxidized low-density lipoproteins (oxLDL) is a major factor contributing to decreased NO-dependent vasodilator function in hypercholesterolemia and atherosclerosis. We investigated whether chronic administration of l-arginine (2% in drinking water) or of α-tocopherol (300 mg/day) improves endothelium-dependent vasodilator function and systemic NO production, reduces vascular oxidative stress, and reduces the progression of atherosclerosis in cholesterol-fed rabbits with pre-existing hypercholesterolemia. Systemic NO production was assessed as urinary nitrate excretion; oxidative stress was measured by urinary 8-iso-PGF 2 α excretion in vivo, by lucigenin-enhanced chemiluminescence of isolated aortic rings ex vivo, and by copper-mediated LDL oxidation in vitro. Endothelium-dependent relaxation was almost completely abrogated in cholesterol-fed rabbits. Urinary nitrate excretion was reduced by 46±10%, and 8-iso-PGF 2 α excretion was increased by 61±18% as compared to controls (each P<0.05). Vascular superoxide radical release stimulated by PMA ex vivo was increased by 273±93% in this group, and the lag time of LDL oxidation was reduced by 35±6% (each P<0.05). Treatment with l-arginine and α-tocopherol reduced intimal lesion formation (by 68±6 and 41±11%, respectively; P<0.05) and improved endothelium-dependent relaxation. Both treatments also normalized urinary 8-iso-PGF 2 α excretion. l-Arginine increased urinary nitrate excretion by 43±13% ( P<0.05) and reduced superoxide radical release by isolated aortic rings to control levels, which was unaffected by vitamin E treatment. By contrast, vitamin E dramatically increased the resistance of isolated LDL to copper-mediated oxidation in vitro by 178±7% ( P<0.05), which was only marginally prolonged by l-arginine. Intimal thickening was reduced by both treatments. We conclude that both l-arginine and α-tocopherol reduce the progression of atherosclerotic plaques in cholesterol-fed rabbits. However, while l-arginine increases NO formation and reduces superoxide release, α-tocopherol antagonizes mainly oxLDL-related events in atherogenesis. Thus, both treatments reduce urinary isoprostane excretion and improve endothelium-dependent vasodilation via different mechanisms.

The exogenous NADH dehydrogenase of heart mitochondria is the key enzyme responsible for selective cardiotoxicity of anthracyclines.

The molecular mechanism of the anthracycline-dependent development of cardiotoxicity is still far from being clear. However, it is generally accepted, that mitochondria play a significant role in triggering this organ specific injury. The results presented in this study demonstrate that, in contrast to liver mitochondria, isolated heart mitochondria shuttle single electrons to adriamycin, giving rise to oxygen radical formation via autoxidation of adriamycin semiquinones. This one electron reduction of anthracyclines is catalyzed by the exogenous NADH dehydrogenase associated with complex I of heart mitochondria, an enzyme which is lacking in liver mitochondria. Upon addition of NADH heart mitochondria generate significant amounts of adriamycin semiquinones while liver mitochondria were ineffective. Adriamycin semiquinones undergo both autoxidation leading to superoxide radical release and complex reactions under formation of adriamycin aglycone. Due to the high lipophilicity adriamycin aglycones accumulate in the inner mitochondrial membrane where they interfere with electron carriers of the respiratory chain. Adriamycin aglycone semiquinones emerging from an interaction with complex I were found to trigger homolytic cleavage of H2O2 which results in the formation of hydroxyl radicals. As demonstrated in this study the activation of adriamycin by the exogenous NADH dehydrogenase of cardiac mitochondria initiates a cascade of reaction steps leading to the establishment of oxidative stress. Our experiments suggest the exogenous NADH dehydrogenase of heart mitochondria to play a key role in the cardiotoxicity of adriamycin. This organ-specific enzyme initiates a sequence of one electron transfer reactions ending up in the establishment of oxidative stress.

Antimutagenic activity of anthocyanins isolated from Aronia melanocarpa fruits

Anthocyanins belong to the flavonoid family and are ubiquitous in plants, especially in flower petals and fruit peels. We established that anthocyanins isolated from fruits of Aronia melanocarpa markedly inhibited the mutagenic activity of benzo( a)pyrene and 2-amino fluorene in the Ames test. In the Sister Chromatid Exchanges (SCEs) test with human blood-derived lymphocytes cultured in vitro, a significant decrease of SCEs frequency induced by benzo( a)pyrene was observed in the presence of anthocyanins. In the case of mitomycin C the effect of anthocyanins on SCEs frequency was smaller but still noticeable. Anthocyanins markedly inhibited the generation and release of superoxide radicals by human grartulocytes. The results suggest that the antimutagenic influence of anthocyanins is exerted mainly by their free-radicals scavenging action as well as by the inhibition of enzymes activating promutagens and converting mutagens to the DNA-reacting derivatives. These preliminary data seem to be important in the aspect of a possible antimutagenic and anticarcinogenic potency of anthocyanins commonly present in fruits and vegetables.