Prooxidant and Antioxidant Activity of Vitamin E Analogues and Troglitazone

Chlorine atom substitution influences radical scavenging activity of 6-chromanol

Synthetic 6-chromanol derivatives were prepared with several chlorine substitutions, which conferred both electron-withdrawing inductive effects and electron-donating resonance effects. A trichlorinated compound (2), a dichlorinated compound (3), and three monochlorinated compounds (4, 5, and 6) were synthesized; compounds 2, 3, and 6 were novel. The antioxidant activities of the compounds, evaluated in terms of their capacities to scavenge galvinoxyl radical, were associated with the number and positioning of chlorine atoms in the aromatic ring of 6-chromanol. The activity of compound 1 (2,2-dimethyl-6-chromanol) was slightly higher than the activities of compounds 2 (2,2-dimethyl-5,7-dichloro-6-chromanol) or 3 (2,2-dimethyl-5,7,8-trichloro-6-chromanol), in which the chlorine atoms were ortho to the phenolic hydroxyl group of 6-chromanol. The scavenging activity of compound 3 was slightly higher than that of 2, which contained an additional chlorine substituted in the 8 position. The activities of polychlorinated compounds 2 and 3 were higher than the activities of any of the monochlorinated compounds (4-6). Compound 6, in which a chlorine was substituted in the 8 position, exhibited the lowest activity. Substitution of a chlorine atom meta to the hydroxyl group of 6-chromanol (compounds 2 and 6) decreased galvinoxyl radical scavenging activity, owing to the electron-withdrawing inductive effect of chlorine. Positioning the chloro group ortho to the hydroxyl group (compounds 4 and 5) retained antioxidant activity because the intermediate radical was stabilized by the electron-donating resonance effect of chlorine in spite of the electron-withdrawing inductive effect of chlorine. Antioxidant activities of the synthesized compounds were evaluated for correlations with the O-H bond dissociation energies (BDEs) and the ionization potentials. The BDEs correlated with the second-order rate constants (k) in the reaction between galvinoxyl radical and the chlorinated 6-chromanol derivatives in acetonitrile. This indicated that the antioxidant mechanism of the synthesized compounds consisted of a one-step hydrogen atom transfer from the phenolic OH group rather than an electron transfer followed by a proton transfer. The synthesized compounds also exhibited hydroxyl radical scavenging capacities in aqueous solution.

Antioxidant poly(lactic-co-glycolic) acid nanoparticles made with α-tocopherol-ascorbic acid surfactant

The goal of the study was to synthesize a surfactant made of α-tocopherol (vitamin E) and ascorbic acid (vitamin C) of antioxidant properties dubbed as EC, and to use this surfactant to make poly(lactic-co-glycolic) acid (PLGA) nanoparticles. Self-assembled EC nanostructures and PLGA-EC nanoparticles were made by nanoprecipitation, and their physical properties (size, size distribution, morphology) were studied at different salt concentrations, surfactant concentrations, and polymer/surfactant ratios. EC surfactant was shown to form self-assembled nanostructures in water with a size of 22 to 138 nm in the presence of sodium chloride, or 12 to 31 nm when synthesis was carried out in sodium bicarbonate. Polymeric PLGA-EC nanoparticles presented a size of 90 to 126 nm for 40% to 120% mass ratio PLGA to surfactant. For the same mass ratios, the PLGA-Span80 formed particles measured 155 to 216 nm. Span80 formed bilayers, whereas EC formed monolayers at the interfaces. PLGA-EC nanoparticles and EC showed antioxidant activity based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay measurements using UV and EPR techniques, antioxidant activity which is not characteristic to commercially available Span80. The thiobarbituric acid reactive substances (TBARS) assay for lipid peroxidation showed that PLGA nanoparticles with EC performed better as antioxidants than the EC nanoassembly or the free vitamin C. Nanoparticles were readily internalized by HepG2 cells and were localized in the cytoplasm. The newly synthesized EC surfactant was therefore found successful in forming uniform, small size polymeric nanoparticles of intrinsic antioxidant properties.

Tuning of the pro-oxidant and antioxidant activity of trolox through the controlled release from biodegradable poly(trolox ester) polymers

In a variety of biomedical applications (e.g., tissue engineering, drug delivery, etc.), the role of a bioactive material is to serve as a platform by which one can modulate the cellular response into a desired role. Of the methods by which one may achieve this control (e.g., shape, structure, binding, growth factor release), the control of the cellular redox state has been under evaluated. Ideally, the ability to tune the redox state of a cell provides an additional level of control over a variety of cellular responses including, cell differentiation, proliferation, and apoptosis. Yet, in order to achieve such control, it is important to know both the overall oxidative status of the cell and what molecular targets are being oxidized. In this work, poly (trolox ester) nanoparticles were evaluated for their ability to either inhibit or induce cellular oxidative stress in a dose-dependent fashion. This polymer delivery form possessed a unique ability to suppress protein oxidation, a feature not seen in the free drug form, emphasizing the advantage of the delivery/dosage formulation has upon regulating cellular response.

Metabolic manipulators: a well founded strategy to combat mitochondrial dysfunction

Whilst the pathophysiology and genetics of mitochondrial disease are slowly being unraveled, currently no effective remedy for mitochondrial disorders is available. One particular strategy in mitochondrial medicine presently under study is metabolic manipulation. This approach is aimed at counteracting the deranged cell biological homeostasis caused by mitochondrial dysfunction, using dietary modifications or small molecule therapy. Cell biological alterations caused by mitochondrial dysfunction include increased reactive oxygen species production, enhanced lipid peroxidation and altered cellular calcium homeostasis. This review covers the five principles of metabolic manipulation: (1) prevention of oxidative damage by reactive oxygen species, (2) amelioration of lipid peroxidation, (3) correction of altered membrane potential, (4) restoration of calcium homeostasis, and (5) transcription regulation interference. We hypothesize that a combination of compounds targeting different metabolic pathways will abolish cellular disturbance arising as a consequences of mitochondrial dysfunction, and thereby improve or stabilize clinical features. However, only a handful of compounds have reached efficacy testing in mammals, and it remains unknown to what extent metabolic manipulation will affect the whole organism. Until a potent remedy is found, patients will remain dependent on supportive, not curative, interventions.

Inhibitory effect of PMC, a potent hydrophilic α-tocopherol derivative, on vascular smooth muscle cell proliferation: the pivotal role of PKC-α translocation

CONTENT

Vascular smooth muscle cells (VSMCs) play a major role in the pathogenesis of atherosclerosis and restenosis, and thus the excessive proliferation of VSMCs contributes to neointimal thickening during atherosclerosis and restenosis. PMC (2,2,5,7,8-pentamethyl-6-hydroxychromane) is the most potent hydrophilic derivative of the alpha-tocopherols; it acts as a potent anti-inflammatory and free-radical scavenger.

OBJECTIVE

The present study was designed to examine the inhibitory mechanisms of PMC in VSMC proliferation.

MATERIALS AND METHODS

VSMC proliferation and cytotoxicity were measured by MTT and LDH assays, respectively. The cell cycle and translocation of PKC-alpha in VSMCs were used by flow cytometry and confocal microscope, respectively. To detect PKC-alpha translocation and activation in VSMCs, immunoblotting was performed in the present study.

RESULTS

In this study, we demonstrate an anti-proliferative effect of PMC in VSMCs. Concentration-dependent inhibition of serum-induced VSMC proliferation was observed in PMC (20 and 50 muM)-treated cells. PMC pretreatment also arrested VSMC cell cycle progression at the G2/M phase. Furthermore, PMC exhibited obvious inhibitory effects on phorbol 12-myristate 13-acetate (PMA)-induced protein kinase C (PKC)-alpha translocation and phospho-(Ser/Thr) substrate phosphorylation.

DISCUSSION AND CONCLUSION

The inhibitory mechanisms of PMC on VSMC proliferation is mediated, at least in part, by inhibition of PKC-alpha translocation and causes cell cycle arrest in the G2/M phase. PMC treatment may represent a novel approach for lowering the risk of or improving function in abnormal VSMC proliferation-related vascular diseases.

The lipophilic antioxidants alpha-tocopherol and coenzyme Q10 reduce the replicative lifespan of Saccharomyces cerevisiae

Reactive oxygen species contribute to cellular ageing and an increased level of oxidative stress is often associated with ageing in many organisms. Supplementation of antioxidants has been advocated to decrease cellular oxidative stress and potentially extend lifespan. A genetically modified K6001 strain of Saccharomyces cerevisiae was employed to determine the effect of several antioxidants, including D-erythroascorbic acid, alpha-tocopherol and coenzyme Q(10) on yeast cell replicative ageing. The replicative lifespan of the K6001 strain was assessed by absorbance change as cells exhibited a linear growth in glucose medium. In this study, water-soluble D-erythroascorbic acid had little effect on cell replicative lifespan. However, supplementation of the growth medium with the lipophilic antioxidants alpha-tocopherol increased oxidative stress and decreased cell lifespan. The use of alpha-tocopherol analogues revealed that the antioxidant activity and the membrane retention ability of alpha-tocopherol were involved in the lifespan reduction effect. Supplementation with either coenzyme Q(10) alone, or in combination with alpha-tocopherol also led to a reduction in yeast replicative lifespan. This study highlights a potential pro-oxidant action of antioxidants.

Effect of Aloe barbadensis Miller juice on oxidative stress biomarkers in aerobic cells using Artemia franciscana as a model

This study reports on the induction of oxidative stress in aerobic cell systems by Aloe barbadensis Miller (Aloe vera) juice using the salt water crustacean Artemia franciscana as a model. A consistent pattern was observed in which Artemia franciscana nauplii responded to Aloe vera juice exposure with a decrease in the overall activity of redox related enzymes. Exposure of Artemia franciscana to sub-lethal levels of Aloe vera juice resulted in a decreased activity of thioredoxin reductase, glutathione reductase and glutathione peroxidase by 34% (66% enzymatic activity), 79% (21% enzymatic activity) and 90% (10% enzymatic activity), respectively. Similarly apparent was the trend whereby the co-exposure of the nauplii to vitamin E counteracted this effect. For each of the biomarker enzymes tested, vitamin E co-exposure resulted in enzyme activities closer to the control value (78%, 56% and 32% of control enzymatic activities for thioredoxin reductase, glutathione reductase and glutathione peroxidase activity, respectively). These results indicate that exposure to sub-lethal doses of Aloe vera juice induces alterations in the cellular redox status of Artemia franciscana and that the addition of vitamin E helps the Artemia franciscana nauplii to overcome/block the juice induced oxidative stress.

Redox agents modulate neuronal activity and reproduce physiological aspects of neuronal aging

The high oxygen consumption and post-mitotic nature of the central nervous system (CNS) makes it particularly susceptible to oxidative stress, the impact of which is widely regarded as a root cause of functional impairment of the aging brain in vertebrates and invertebrates alike. Using an invertebrate model system we demonstrate that the lipid soluble antioxidant α-tocopherol can both reverse 2,2-azobis(2-methylpropion-amidine) dihydrochloride (AAPH) induced decline in excitability in young neurons as well as restore the electrical activity and excitability of aged neurons not unlike the level of their younger equivalents. Furthermore, using two analogs of α-tocopherol where either the acyl chain has been removed (Trolox) or the hydroxyl group of the chromanol ring has been methylated we were able to assert that the restorative effect of α-tocopherol requires both insertion into the plasma membrane as well as an active OH group. Thus, our results indicate peroxidation is an important modulator of neuronal excitability as well as support the growing body of evidence suggesting α-tocopherol's actions may extend well beyond its established role as a lipid domain preventative antioxidant.

Melatonin and Trolox ameliorate duodenal LPS-induced disturbances and oxidative stress

BACKGROUND AND AIMS

Lipopolysaccharide evokes gastrointestinal motility disturbances and oxidative stress. The aims of the present study were to investigate the effect of melatonin and Trolox in the actions of lipopolysaccharide on duodenal contractility and on lipid peroxidation in rabbit duodenum.

METHODS

The in vitro duodenal contractility studies were carried out in organ bath and the levels of malondialdehyde were assayed by spectrophotometry. Duodenal segments were incubated with lipopolysaccharide (0.3 microg mL(-1)).

RESULTS

Lipopolysaccharide decreased acetylcholine-induced contractions and increased malondialdehyde and 4-hydroxyalkenals concentrations in homogenates of duodenum. Melatonin reduced the amplitude of spontaneous contractions in duodenal muscle. Acetylcholine-induced contractions were not altered by melatonin in longitudinal and circular muscles. Trolox decreased the amplitude of spontaneous contractions of duodenal muscle. Trolox (1.2 or 4 mM) did not alter acetylcholine-induced contractions in duodenal muscle, but the concentration of 12 mM diminished the frequency of contractions and acetylcholine-induced contractions. Melatonin (0.3 mM) or Trolox (4 mM) diminished malondialdehyde and 4-hydroxyalkenals levels induced by lipopolysaccharide in the duodenum.

CONCLUSIONS

Melatonin and Trolox reduce oxidative stress induced by lipopolysaccharide and ameliorate the effect of lipopolysaccharide on duodenal contractility.

Evaluation of equol function on anti- or prooxidant status in vivo

The present study was performed to investigate the effects of equol on oxidative stress and the antioxidant defense system in the livers of mice. Mice were orally administered equol at either 5 or 25 mg/kg body weight/day for 1, 3, or 7 wk. Equol administration significantly inhibited biomarkers of oxidative stress (thiobarbituric acid-reactive substances value, carbonyl content, and serum 8-OH-dG) at all doses and for all durations of administration, and this phenomenon was most pronounced at 3 wk. Moreover, catalase and total superoxide dismutase (SOD) activities and their mRNA expression were significantly increased by equol. Although equol increased the glutathione peroxidase (GSH-px) activity in mice treated with equol for 1 wk, long-term administration of equol (7 wk) caused a decrease in the ratio of reduced/oxidized glutathione (GSH/GSSG) and the activities of GSH-px and glutathione reductase (GR). Taken together, these results suggest that equol may act as an antioxidant through an inhibition of oxidative stress and stimulation of catalase and SOD, but can also cause prooxidant effects such as reduction of the GSH/GSSG ratio, depending on the treatment period.

Alpha-tocopherol modulates human umbilical vein endothelial cell expression of Cu/Zn superoxide dismutase and catalase and lipid peroxidation

Recent studies suggest the potential of alpha-tocopherol as a gene regulator, possibly through peroxisome proliferator-activated receptor gamma (PPARgamma) activation due to the structural similarity of alpha-tocopherol to a PPARgamma ligand, troglitazone. Other investigators have suggested that a link exists between induction of the antioxidant enzymes Cu/Zn superoxide dismutase (SOD) and catalase and PPARgamma activation. This study was designed to examine whether alpha-tocopherol modulates expression of Cu/Zn SOD and catalase in human umbilical vein endothelial cells through redox-sensitive transcription factors, PPARgamma, and nuclear factor-kappaB (NF-kappaB). Alpha-tocopherol treatments showed significant increases in both PPARgamma (1.4- to 2.2-fold, P < .01) and NF-kappaB p50 (1.3- to 1.5-fold, P < .005) DNA binding activities compared with vehicle control. Significant increases in Cu/Zn SOD mRNA levels (6.0-fold, P < .005) and catalase mRNA (8.0-fold, P < .005) and its protein levels (2.3-fold, P < .005) and lipid peroxidation levels (5.3-fold, P < .005) were observed at the lowest concentration (10 mumol/L) of alpha-tocopherol treatments. Both mRNA and protein levels of these 2 antioxidant enzymes were positively associated with lipid peroxidation (P < .05). Alpha-tocopherol may play a role not only in preventing against oxidative damage as an exogenous antioxidant by scavenging free radicals and superoxide but also in modulating the expression of the endogenous antioxidant enzymes as a gene regulator through PPARgamma and NF-kappaB in the vascular cells. The alpha-tocopherol-mediated gene expression is either stimulatory or inhibitory, depending on its oxidative status or its concentrations.

Antioxidant supplementation in sepsis and systemic inflammatory response syndrome

OBJECTIVE

Summarize the current knowledge about oxidative stress-related organ dysfunction in inflammatory and septic conditions, and its potential prevention and treatment by antioxidants in critically ill patients, focusing on naturally occurring antioxidants and clinical trials.

STUDY SELECTION

PubMed, MEDLINE, and personal database search.

SYNTHESIS

Plasma concentrations of antioxidant micronutrients are depressed during critical illness and especially during sepsis. The causes of these low levels include losses with biological fluids, low intakes, dilution by resuscitation fluids, as well as systemic inflammatory response syndrome-mediated redistribution of micronutrients from plasma to tissues. Numerous clinical trials have been conducted, many of which have shown beneficial effects of supplementation. Interestingly, among the candidates, glutamine, glutathione, and selenium are linked with the potent glutathione peroxidase enzyme family at some stage of their synthesis and metabolism.

CONCLUSIONS

Three antioxidant nutrients have demonstrated clinical benefits and reached level A evidence: a) selenium improves clinical outcome (infections, organ failure); b) glutamine reduces infectious complication in large-sized trials; and c) the association of eicosapentaenoic acid and micronutrients has significant anti-inflammatory effects. Other antioxidants are still on the clinical benchmark level, awaiting well-designed clinical trials.

Quasi-simultaneous determination of antioxidative activities against superoxide anion and nitric oxide by a combination of sequential injection analysis and flow injection analysis with chemiluminescence detection

A method that combines sequential injection analysis (SIA), flow injection analysis and chemiluminescence (CL) detection was developed for the quasi-simultaneous determination of antioxidative activities against superoxide anion (O2-) and nitric oxide (NO). The antioxidative activity was expressed as the decrease in luminol CL intensity caused by the quenching of O2- or NO by an antioxidant. The SIA system consisted of two syringe pumps, two selection valves, two holding coils, an HPLC pump to deliver luminol solution, and a CL detector. Operation of the syringe pumps and multiport valves was controlled automatically using a personal computer with appropriate software. A hypoxanthine (HX)-xanthine oxidase (XOD) system was used for the generation of O2-, and (+/-)-(E)-4-methyl-2-[(E)-hydroxyimino]-5-nitro-6-methoxy-3-hexenamide (NOR1) was employed as NO donor agent. The repeatability of the method was evaluated with 35.2 microg ml(-1) L-ascorbic acid, and the relative standard deviations (RSD) of the antioxidative activities were less than 3.8%. The quasi-simultaneous determination of the antioxidative activities in one sample was completed within 2.0 min. The antioxidative activities of some antioxidants and commercially available supplements containing certain antioxidants were successfully determined using this system. The proposed system is rapid and reproducible, and thus may be useful for the screening of functional foods, supplements and pharmaceutical formulations that exhibit antioxidative activity.

Dual role of hydrogen peroxide in cancer: Possible relevance to cancer chemoprevention and therapy

Accumulating evidence suggests that hydrogen peroxide (H(2)O(2)) plays an important role in cancer development. Experimental data have shown that cancer cells produce high amounts of H(2)O(2). An increase in the cellular levels of H(2)O(2) has been linked to several key alterations in cancer, including DNA alterations, cell proliferation, apoptosis resistance, metastasis, angiogenesis and hypoxia-inducible factor 1 (HIF-1) activation. It has also been observed that the malignant phenotype of cancer cells can be reversed just by decreasing the cellular levels of H(2)O(2). On the other hand, there is evidence that H(2)O(2) can induce apoptosis in cancer cells selectively and that the activity of several anticancer drugs commonly used in the clinic is mediated, at least in part, by H(2)O(2). The present report discusses that the high levels of H(2)O(2) commonly observed in cancer cells may be essential for cancer development; these high levels, however, seem almost incompatible with cell survival and may make cancer cells more susceptible to H(2)O(2)-induced cell death than normal cells. An understanding of this dual role of H(2)O(2) in cancer might be exploited for the development of cancer chemopreventive and therapeutic strategies.

Vitamin E, antioxidant and nothing more

All of the naturally occurring vitamin E forms, as well as those of synthetic all-rac-alpha-tocopherol, have relatively similar antioxidant properties, so why does the body prefer alpha-tocopherol as its unique form of vitamin E? We propose the hypothesis that all of the observations concerning the in vivo mechanism of action of alpha-tocopherol result from its role as a potent lipid-soluble antioxidant. The purpose of this review then is to describe the evidence for alpha-tocopherol's in vivo function and to make the claim that alpha-tocopherol's major vitamin function, if not only function, is that of a peroxyl radical scavenger. The importance of this function is to maintain the integrity of long-chain polyunsaturated fatty acids in the membranes of cells and thus maintain their bioactivity. That is to say that these bioactive lipids are important signaling molecules and that changes in their amounts, or in their loss due to oxidation, are the key cellular events that are responded to by cells. The various signaling pathways that have been described by others to be under alpha-tocopherol regulation appear rather to be dependent on the oxidative stress of the cell or tissue under question. Moreover, it seems unlikely that these pathways are specifically under the control of alpha-tocopherol given that various antioxidants other than alpha-tocopherol and various oxidative stressors can manipulate their responses. Thus, virtually all of the variation and scope of vitamin E's biological activity can be seen and understood in the light of protection of polyunsaturated fatty acids and the membrane qualities (fluidity, phase separation, and lipid domains) that polyunsaturated fatty acids bring about.

Studies in Vitamin E: Biochemistry and Molecular Biology of Tocopherol Quinones

Tocopherols and tocotrienols, parent congeners in the vitamin E family, function as phenolic antioxidants. However, there has been little interest in their quinone electrophiles formed as a consequence of oxidation reactions, even though unique biological properties were suggested by early studies conducted immediately after the discovery of vitamin E. Oxidation of tocopherols and tocotrienols produces para- and ortho-quinones, and quinone methides, while oxidation of their carboxyethyl hydroxychroman derivatives produces quinone lactones. These quinone electrophiles are grouped in two subclasses, the nonarylating fully methylated alpha-family and the arylating desmethyl beta-, gamma-, and delta-family. Arylating quinone electrophiles form Michael adducts with thiol nucleophiles, provided by cysteinyl proteins or peptides, which can be identified and quantified by tetramethylammonium hydroxide thermochemolysis. They have striking biological properties which differ significantly from their nonarylating congeners. They are highly cytotoxic, inducing characteristic apoptotic changes in cultured cells. Cytotoxicity is intimately associated with the induction of endoplasmic reticulum stress and a consequent unfolded protein response involving the pancreatic ER kinase (PERK) signaling pathway that commits overstressed cells to apoptosis. The step-function difference between arylating and nonarylating tocopherol quinones is conceivably the basis for distinct biological properties of parent tocopherols, including the epigenetic modification of a histone thiol, the ceramide pathway, natriuresis, and the activity of COX-2, NF-kappaB, PPARgamma, and cyclin. The role of alpha-tocopherol in the origin and evolution of the western hominin diet, the so-called "Mediterranean" diet, and the prominence of alpha-tocopherol in colostrum, mother's milk, and infant nutrition are considered. Finally, the discordance introduced into the diet by arylating tocopherol quinone precursors through the wide use of vegetable oils in deep-frying is recognized.

Update on clinical micronutrient supplementation studies in the critically ill

PURPOSE OF REVIEW

During the past 2 years a number of studies, meta-analyses and reviews have shown that micronutrient supplementation may be beneficial in critical illness. Selenium is emerging as a particularly important micronutrient. This paper reviews the evidence from trials in the critically ill, putting mechanisms, methods and shortcomings into perspective.

RECENT FINDINGS

There is growing evidence that antioxidant supplements, particularly high-dose selenium, may reduce mortality, infectious complications, and improve wound healing. Deleterious effects may result from prolonged high doses, whereas short-term high dose supplements are probably safe in most critically ill populations.

SUMMARY

Plasma micronutrient concentrations are low during critical illness, as a result of losses, low intakes and dilution, and redistribution from plasma to tissues. An assessment of status is difficult. Micronutrient supplements appear beneficial in conditions such as major burns, trauma and sepsis and stroke, and are most likely to benefit patients with previous or actual depletion. The intravenous route seems more efficient than the enteral. Although chronic high intakes may be harmful, short-term interventions appear to be free of deleterious effects. Further research is required to determine the optimal micronutrient combinations and the doses required according to the timing of intervention and severity of disease.

Effects of hesperetin on vessel structure formation in mouse embryonic stem (mES) cells

OBJECTIVE

The present study investigated the effects of hesperetin on vessel structure formation in mouse embryonic stem (mES) cells with regard to whether hesperetin acts as an antioxidant or pro-oxidant. Some flavonoids enhance antioxidant systems while increasing oxidative stress in the body.

METHODS

After their differentiation into endothelial-like cells for 10 d, mES cells were treated with 1 to 100 muM of hesperetin for 24 h.

RESULTS

Hesperetin efficiently inhibited the formation of vessel-like tubular structures consisting of platelet-endothelial cell adhesion molecule-1-immunoreactive cells and significantly (P < 0.05) increased the generation of reactive oxygen species in a concentration-dependent manner. Although glutathione (in its reduced and oxidized forms) in mES cells was not affected by hesperetin, the 8-iso-prostaglandin F2(alpha) content was decreased. In addition, cytotoxicity-induced hesperetin was not found; lactate dehydrogenase release and cell viability were determined as an index of cell damage.

CONCLUSION

Taken together, the present study shows that hesperetin inhibits vessel formation by pro-oxidant means and suggests its potential as an antiangiogenic agent.

Bioactive 1,4-dihydroisonicotinic acid derivatives prevent oxidative damage of liver cells

1,4-Dihydroisonicotinic acid derivatives (1,4-DHINA) are compounds closely related to derivatives of 1,4-dihydropyridine, a well-known calcium channel antagonists. 1,4-DHINA we used were derived from a well-known antioxidant Diludin. Although some compounds have neuromodulatory or antimutagenic properties, their activity mechanisms are not well known. This study was performed to obtain data on antioxidant and bioprotective activities of: 2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydroisonicotinic acid (Ia); sodium 2-(2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridine-4-carboxamido)glutamate (Ib) and sodium 2-(2,6-dimethyl-3,5-diethoxycarbonyl-1,4-dihydropyridine-4-carboxamido)ethane-sulphate (Ic). 1,4-DHINA's activities were studied in comparison to Trolox by: N,N-Diphenyl-N'-picrylhydrazyl (DPPH*), deoxyribose degradation, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical scavenging and antioxidative capacity assays; copper-induced lipid peroxidation of cultured rat liver cells (malondialdehyde determination by high performance liquid chromatography and 4-hydroxynonenal-protein conjugates by dot-blot); (3)H-thymidine incorporation and trypan blue assay for liver cells growth and viability. In all assays used Ia was the most potent antioxidant. Ia was also a potent antioxidant at non-toxic concentrations for liver cell cultures. It completely abolished, while Ic only slightly decreased copper-induced lipid peroxidation of liver cells. Thus, antioxidant capacities are important activity principle of Ia, which was even superior to Trolox in the cell cultures used, while activity principles of Ic and Ib remain yet to be determined.

Simultaneous quantification of oxidative stress and cell spreading using 5-(and-6)-chloromethyl-2′,7′-dichlorofluorescein

BACKGROUND

Mitochondrial dysfunction may lead to increased oxidative stress and consequent changes in cell spreading. Here, we describe and validate a novel method for simultaneous quantification of these two parameters.

METHODS

Human skin fibroblasts were loaded with 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein (CM-H(2)DCF), and its oxidative conversion into CM-DCF was monitored as a function of time by video-rate confocal microscopy and real-time image averaging. Cell size was determined after binarization of the acquired images.

RESULTS

At the lowest practical laser output, CM-DCF formation occurred with zero order kinetics, indicating that [CM-H(2)DCF] was not rate-limiting and that the rate of [CM-DCF] formation (V(CM-DCF)) was a function of the cellular oxidant level. Analysis of fibroblasts of a healthy control subject and a patient with a deficiency of NADH:ubiquinone oxidoreductase, the first complex of the oxidative phosphorylation system, revealed a significant increase in cellular oxidant level in the latter cells that was, however, not accompanied by a change in cell spreading. Conversely, chronic treatment with 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), a derivative of vitamin E, markedly decreased the oxidant level and cell spreading in both control and patient fibroblasts.

CONCLUSIONS

We present a reliable method for simultaneous quantification of oxidant levels and cell spreading in living cells.