Reactive oxygen species in human health and disease

Therapeutic Potential of Polar and Non-Polar Extracts of Cyanthillium cinereum In Vitro

Cyanthillium cinereum (Less.) H. Rob. (Asteraceae) has been traditionally known for its medicinal properties, all aspects of which are yet to be exploited. This study was aimed at investigating the therapeutic potential of polar (methanolic and aqueous) and nonpolar (hexane and chloroform) crude extracts of the whole plant. Several parameters including free-radical (DPPH^•, ABTS^•+, H₂O₂ and ^•OH) scavenging, reducing power, protection of DNA against oxidative damage, cytotoxicity, inhibition of oxidative hemolysis in erythrocytes, total phenolic content and inhibition of lipid peroxidation were examined. All the free-radical generating assay models demonstrated positive scavenging efficiency with differential but considerable magnitudes for the four extracts. However, only the hexane extract showed significant H₂O₂ scavenging effect. Lipid peroxidation was estimated by thiobarbituric acid-malondialdehyde (MDA) reaction, and a high degree of inhibition was shown by all the extracts. Reducing power of the polar extracts was higher than the non-polar ones. All extracts showed a concentration-dependent increase in phenolic contents. Oxidative damage to erythrocytes was hindered by all extracts in diverse degrees. XTT assay showed that all extracts have mild cytotoxic property. The aqueous extract evidently demonstrated protective effect on pBR322 plasmid DNA against oxidative breakdown. These results suggested the potential of C. cinereum as medicine against free-radical-associated oxidative damage and related degenerative diseases involving metabolic stress, genotoxicity and cytotoxicity.

Preventive effect of phytoglycoprotein (27 kDa) on inflammatory factors at liver injury in cadmium chloride-exposed ICR mice

Cadmium is one of the inflammation-related xenobiotics and has been regarded as a potent carcinogen. Gardenia jasminoides Ellis (GJE) has been used to cure inflammation in Korean folk medicine for a long time. The purpose of present study is the inhibitory effect of glycoprotein isolated from GJE (27 kDa) on inflammation mechanism in cadmium chloride-exposed ICR mice. We evaluated the activities of lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and thiobarbituric acid-reactive substances (TBARS), activities of anti-oxidative enzymes [superoxide dismutase (SOD) and gluthathione peroxidase (GPx)], activities of c-Jun N-terminal protein kinase (JNK), heat shock protein 27 (Hsp27), activator protein (AP)-1, nuclear factor (NF)-κB and expression of inflammation-related mediators including tumor necrosis factor (TNF)-α and interleukin (IL)-6 in cadmium chloride-exposed ICR mice using immunoblot analysis, EMSA and RT-PCR. It notes that mice plasma was used to measure ALT, LDH, and TBARS after treatment with cadmium chloride alone or cadmium chloride under the pretreatment with GJE glycoprotein. Liver tissues were used to assess activities of anti-oxidant enzymes, SAPK/JNK, Hsp27, AP-1, NF-κB, TNF-α, and IL-6 in this study. The results obtained from this study revealed that GJE glycoprotein (10 mg/kg) decreased the levels of LDH, ALT and TBARS, whereas increased the activity of hepatic anti-oxidant enzymes (SOD and GPx) in cadmium chloride-exposed ICR mice. Moreover, it decreased the activity of JNK/AP-1, NF-κB, Hsp27, and pro-inflammatory cytokines (TNF-α and IL-6). Taken together, the results in this study suggest that GJE glycoprotein inhibits the expression of inflammation-related cytokines (TNF-α and IL-6) in cadmium chloride-exposed ICR mice.

Dietary supplements and human health: for better or for worse?

Encouraged by the potential health benefits of higher dietary intake of substances with beneficial properties, the use of supplements containing these compounds has increased steadily over recent years. The effects of several of these, many of which are antioxidants, have been supported by data obtained in vitro, in animal models, and often by human studies as well. However, as carefully controlled human supplementation trials have been conducted, questions about the efficacy and safety of these supplements have emerged. In this Educational Paper, three different supplements were selected for consideration of the benefits and risks currently associated with their intake. The selected supplements include β-carotene, selenium, and genistein. The use of each is discussed in the context of preclinical and clinical data that provide evidence for both their use in reducing disease incidence and the possible liabilities that accompany their enhanced consumption. Variables that may influence their impact, such as lifestyle habits, baseline nutritional levels, and genetic makeup are considered and the application of these issues to broader classes of supplements is discussed.

Zinc-suppressed inflammatory cytokines by induction of A20-mediated inhibition of nuclear factor-κB

OBJECTIVE

Chronic generation of inflammatory cytokines and reactive oxygen species are implicated in atherosclerosis, aging, cancers, and other chronic diseases. We hypothesized that zinc induces A20 in premonocytic, endothelial, and cancer cells, and A20 binds to tumor necrosis factor (TNF)-receptor associated factor, and inhibits Iκ kinase-α (IKK-α)/nuclear factor-κB (NF-κB), resulting in downregulation of TNF-α and interleukin-1β (IL-1β).

METHODS

To test this hypothesis, we used HL-60, human umbilical vein endothelial cells, and SW480 cell lines under zinc-deficient and zinc-sufficient conditions in this study. We measured oxidative stress markers, inflammatory cytokines, A20 protein and mRNA, A20-FRAF-1 complex, and IKK-α/NF-κB signaling in stimulated zinc-deficient and zinc sufficient cells. We also conducted antisense A20 and siRNA studies to investigate the regulatory role of zinc in TNF-α and IL-1β via A20.

RESULTS

We found that zinc increased A20 and A20-tumor necrosis factor-receptor associated factor-1 complex, decreased the IKK-α/NF-κB signaling pathway, oxidative stress markers, and inflammatory cytokines in these cells compared with zinc-deficient cells. We confirmed that zinc-induced A20 contributes to downregulation of TNF-α and IL-1β by antisense and short interfering RNA A20 studies.

CONCLUSION

Our studies suggest that zinc suppresses generation of NF-κB-regulated inflammatory cytokines by induction of A20.

Antioxidant flavone glycosides from the leaves of Fargesia robusta

The aqueous methanolic leaf extract of Fargesia robusta var. Pingwu was evaluated in vitro for its antioxidant capacity using the TEAC and ORAC assays. C-Glycosyl flavones, farobin A (1) and farobin B (2), together with three known compounds, tricin-5-O-glucopyranoside (3), 2''-O-α-rhamnosyl-6-C-(6-deoxy-ribo-hexos-3-ulosyl)luteolin (4), and luteolin-6-C-glucopyranoside (homoorientin) (5), were isolated from the hydroalcoholic extract of the leaves of F. robusta. The structures of the compounds were determined by spectroscopic analyses including UV, 1D and 2D NMR, and MS. Compounds 1, 4, and 5 exhibited potent antioxidant activity in the TEAC assay, while compounds 1, 3, and 5 showed the highest antioxidant capacity in the ORAC assay.

In vivo hepatoprotective activity of the aqueous extract of Artemisia absinthium L. against chemically and immunologically induced liver injuries in mice

AIM OF THE STUDY

This study aimed to evaluate in vivo hepatoprotective activity of the aqueous extract of Artemisia absinthium L. (AEAA), which has been used for the treatment of liver disorders in Traditional Uighur Medicine.

MATERIALS AND METHODS

Qualitative and quantitative phytochemical analysis of the AEAA was performed by means of thin layer chromatography and spectrophometric assays. Aqueous extract (50, 100 or 200 mg/kg body weight/day) was administered orally to experimental mice. Liver injury was induced chemically, by a single CCl(4) administration (0.1% in olive oil, 10 ml/kg, i.v.), or immunologically, by injection of endotoxin (LPS, 10 microg, i.v.) in BCG-primed mice. The levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1) in mouse sera, as well as superoxide dismutase (SOD), glutathione peroxidase (GPx) and malondialdehyde (MDA) in mouse liver tissues were measured. The biochemical observations were supplemented by histopathological examination.

RESULTS

Obtained results demonstrated that the pretreatment with AEAA significantly (P<0.001) and dose-dependently prevented chemically or immunologically induced increase in serum levels of hepatic enzymes. Furthermore, AEAA significantly (P<0.05) reduced the lipid peroxidation in the liver tissue and restored activities of defense antioxidant enzymes SOD and GPx towards normal levels. In the BCG/LPS model, increase of the levels of important pro-inflammatory mediators TNF-alpha and IL-1 was significantly (P<0.01) suppressed by AEAA pretreatment. Histopathology of the liver tissue showed that AEAA attenuated the hepatocellular necrosis and led to reduction of inflammatory cells infiltration. Phytochemical analyses revealed the presence of sesquiterpene lactones, flavonoids, phenolic acids and tannins in the AEAA.

CONCLUSIONS

The results of this study strongly indicate the protective effect of AEAA against acute liver injury which may be attributed to its antioxidative and/or immunomodulatory activity, and thereby scientifically support its traditional use.

Zinc in cancer prevention

Essentiality of zinc for humans was discovered 45 yr ago. Deficiency of zinc is prevalent world wide in developing countries and may affect nearly 2 billion subjects. The major manifestations of zinc deficiency include growth retardation, hypogonadism in males, cell-mediated immune dysfunctions, and cognitive impairment. Zinc not only improves cell mediated immune functions but also functions as an antioxidant and anti-inflammatory agent. Oxidative stress and chronic inflammation have been implicated in development of many cancers. In patients with head and neck cancer, we have shown that nearly 65% of these patients were zinc deficient based on their cellular zinc concentrations. Natural killer (NK) cell activity and IL-2 generation were also affected adversely. Th2 cytokines were not affected. In our patients, zinc status was a better indicator of tumor burden and stage of disease in comparison to the overall nutritional status. Zinc status also correlated with number of hospital admissions and incidences of infections. NF-kappa B is constitutively activated in many cancer cells, and this results in activation of antiapoptotic genes, VEGF, cyclin DI, EGFR, MMP-9 and inflammatory cytokines. Zinc inhibits NF-kappa B via induction of A-20. Thus, zinc supplementation should have beneficial effects on cancer by decreasing angiogenesis and induction of inflammatory cytokines while increasing apoptosis in cancer cells. Based on the above, we recommend further studies and propose that zinc should be utilized in the management and chemoprevention of cancer.

AMPKalpha1 deletion shortens erythrocyte life span in mice: role of oxidative stress

AMP-activated protein kinase (AMPK) is an energy sensor essential for maintaining cellular energy homeostasis. Here, we report that AMPKalpha1 is the predominant isoform of AMPK in murine erythrocytes and mice globally deficient in AMPKalpha1 (AMPKalpha1(-/-)), but not in those lacking AMPKalpha2, and the mice had markedly enlarged spleens with dramatically increased proportions of Ter119-positive erythroid cells. Blood tests revealed significantly decreased erythrocyte and hemoglobin levels with increased reticulocyte counts and elevated plasma erythropoietin concentrations in AMPKalpha1(-/-) mice. The life span of erythrocytes from AMPKalpha1(-/-) mice was less than that in wild-type littermates, and the levels of reactive oxygen species and oxidized proteins were significantly increased in AMPKalpha1(-/-) erythrocytes. In keeping with the elevated oxidative stress, treatment of AMPKalpha1(-/-) mice with the antioxidant, tempol, resulted in decreased reticulocyte counts and improved erythrocyte survival. Furthermore, the expression of Foxo3 and reactive oxygen species scavenging enzymes was significantly decreased in erythroblasts from AMPKalpha1(-/-) mice. Collectively, these results establish an essential role for AMPKalpha1 in regulating oxidative stress and life span in erythrocytes.

Oxidative stress and cognitive longevity

OBJECTIVE

The potential relation between metabolic activity within the central nervous system and retention of cognitive functioning capacity was assessed.

METHODS

A detailed literature review was conducted and summarized.

RESULTS

A large body of scientific evidence describes the interactions among cognitive activity, oxidative stress, neurodegeneration, neuroprotection, cognitive aging, and retention of cognitive functioning ability.

CONCLUSION

Maintenance of redox balance within the central nervous system can forestall cognitive decline and promote cognitive longevity.

Reactive oxygen species activity and chemical speciation of size-fractionated atmospheric particulate matter from Lahore, Pakistan: an important role for transition metals

In this study a sensitive macrophage-based in vitro reactive oxygen species (ROS) assay was coupled with chemical fractionation tools and a year-long sampling program to further our understanding of the role of water-soluble metals in aerosol toxicity. The location is the polluted urban environment of Lahore, Pakistan, where we collected 24 h PM10 and PM2.5 samples every 6(th) day from January 2007 through January 2008. The intrinsic (i.e. particulate matter (PM) mass-normalized) toxicity of the Lahore aerosol, representative of highly polluted developing nations, is compared with toxicity of aerosols from several urban environments in the USA. The monthly patterns of PM2.5 and PM10 water-soluble aerosol ROS-activity were similar with maxima in fall and mid-late winter, and minima over the period April through August and in early winter. Coarse PM ROS-activity was a consistent and significant component (42 +/- 13%) of total activity. The intrinsic activity of the PM2.5 and coarse PM was remarkably similar in a given month. Chelex treatment of the Lahore PM extracts removed a very large and consistent fraction of the water-soluble ROS-activity (96.5 +/- 2.8% for the PM10). Desferrioxamine (DFO) treatment of these extracts also removed a large and relatively consistent fraction of the water-soluble ROS-activity (87.8 +/- 5.3%). Taken together, the DFO and Chelex data imply that transition metals, particularly iron, are major factors mediating ROS-activity of water extracts of the Lahore PM. Statistical modeling (step-wise linear regression and cluster analysis) identified a small subset of metals (Mn, Co, Fe, Ni) as the potential ROS-active species. Several water-soluble "trace" metals present at very high concentrations in the PM extracts (Zn, Pb, Cd), that were effectively removed on Chelex, but are not redox-active, exhibited relatively poor correlations with ROS. The median intrinsic water-soluble ROS-activity measured in the Lahore PM was more than an order-of-magnitude greater than that measured in aerosols from the Long Beach/Los Angeles region and approximately 4-fold greater than the activity of Denver area PM.

Choline supplementation reduces oxidative stress in mouse model of allergic airway disease

BACKGROUND

Asthma is a multi-factorial inflammatory disease associated with increased oxidative stress and altered antioxidant defences. We have evaluated the effect of choline on oxidative stress in a mouse model of airway disease.

MATERIALS AND METHODS

Balb/c mice were sensitised with 100 microg of ovalbumin on days 0 and 14, and challenged with aerosolized ovalbumin on days 25-27. Mice were administered 1 mg kg(-1) of choline via oral gavage or intranasal route on days 14-27. Mice were also administered 100 mg kg(-1) of alpha-lipoic acid as standard antioxidant. Total cell counts, eosinophils and eosinophil peroxidase (EPO) activity were determined in bronchoalveolar lavage (BAL) fluid. Reactive oxygen species (ROS), lipid peroxidation and isoprostanes levels were measured in BAL fluid. IL-13 and tumour necrosis factor-alpha (TNF-alpha) levels were also measured in BAL fluid and spleen cell culture supernatant. Nuclear factor kappaB (NFkappaB) p65 protein expression was measured after last ovalbumin challenge in nuclear and cytosolic extracts of lungs.

RESULTS

Compared with ovalbumin-challenged mice, choline and alpha-lipoic acid treated mice had significantly reduced eosinophilic infiltration and EPO activity in BAL fluid. Choline and alpha-lipoic acid treatment reduced ROS production and isoprostanes level significantly in BAL fluid and thus suppressed oxidative stress. Choline and alpha-lipoic acid administration by either route decreased lipid peroxidation levels and down regulated NFkappaB activity. Further, choline and/or alpha-lipoic acid treatment suppressed TNF-alpha level significantly as compared with that of ovalbumin-challenged mice.

CONCLUSIONS

Choline administration reduces oxidative stress possibly by modulating the redox status of the cell and inhibits inflammatory response in a mouse model.

Transduction of redox signaling by electrophile-protein reactions

Over the last 50 years, the posttranslational modification (PTM) of proteins has emerged as a central mechanism for cells to regulate metabolism, growth, differentiation, cell-cell interactions, and immune responses. By influencing protein structure and function, PTM leads to a multiplication of proteome diversity. Redox-dependent PTMs, mediated by environmental and endogenously generated reactive species, induce cell signaling responses and can have toxic effects in organisms. PTMs induced by the electrophilic by-products of redox reactions most frequently occur at protein thiols; other nucleophilic amino acids serve as less favorable targets. Advances in mass spectrometry and affinity-chemistry strategies have improved the detection of electrophile-induced protein modifications both in vitro and in vivo and have revealed a high degree of amino acid and protein selectivity of electrophilic PTM. The identification of biological targets of electrophiles has motivated further study of the functional impact of various PTM reactions on specific signaling pathways and how this might affect organisms.

Telomeric D-loops containing 8-oxo-2'-deoxyguanosine are preferred substrates for Werner and Bloom syndrome helicases and are bound by POT1

8-Oxo-2'-deoxyguanosine (8-oxodG) is one of the most important oxidative DNA lesions, and G-rich telomeric DNA is especially susceptible to oxidative DNA damage. RecQ helicases WRN and BLM and telomere-binding protein POT1 are thought to play roles in telomere maintenance. This study examines the ability of WRN, BLM, and RecQ5 to unwind and POT1 to bind telomeric D-loops containing 8-oxodG. The results demonstrate that WRN and BLM preferentially unwind telomeric D-loops containing 8-oxodG and that POT1 binds with higher affinity to telomeric D-loops with 8-oxodG but shows no preference for telomeric single-stranded DNA with 8-oxodG. We speculate that telomeric D-loops with 8-oxodG may have a greater tendency to form G-quadruplex DNA structures than telomeric DNA lacking 8-oxodG.

Analysis of 7,8-dihydro-8-oxo-2'-deoxyguanosine in cellular DNA during oxidative stress

Analysis of cellular 7,8-dihydro-8-oxo-2′-deoxyguanosine (8-oxo-dGuo) as a biomarker of oxidative DNA damage has been fraught with numerous methodological problems. This is primarily due to artifactual oxidation of dGuo that occurs during DNA isolation and hydrolysis. Therefore, it has become necessary to rely on using the comet assay, which is not necessarily specific for 8-oxo-dGuo. A highly specific and sensitive method based on immunoaffinity purification and stable isotope dilution liquid chromatography (LC)-multiple reaction monitoring (MRM)/mass spectrometry (MS) that avoids artifact formation has now been developed. Cellular DNA was isolated using cold DNAzol (a proprietary product that contains guanidine thiocyanate) instead of chaotropic- or phenol-based methodology. Chelex-treated buffers were used to prevent Fenton chemistry-mediated generation of reactive oxygen species (ROS) and artifactual oxidation of DNA bases. Deferoxamine was also added to all buffers in order to complex any residual transition metal ions remaining after Chelex treatment. The LC-MRM/MS method was used to determine that the basal 8-oxo-dGuo level in DNA from human bronchoalveolar H358 cells was 2.2 ± 0.4 8-oxo-dGuo/10⁷ dGuo (mean ± standard deviation) or 5.5 ± 1.0 8-oxo-dGuo/10⁸ nucleotides. Similar levels were observed in human lung adenocarcinoma A549 cells, mouse hepatoma Hepa-1c1c7 cells, and human HeLa cervical epithelial adenocarcinoma cells. These values are an order of magnitude lower than is typically reported for basal 8-oxo-dGuo levels in DNA as determined by other MS- or chromatography-based assays. H358 cells were treated with increasing concentrations of potassium bromate (KBrO₃) as a positive control or with the methylating agent methyl methanesulfonate (MMS) as a negative control. A linear dose−response for 8-oxo-dGuo formation (r² = 0.962) was obtained with increasing concentrations of KBrO₃ in the range of 0.05 mM to 2.50 mM. In contrast, no 8-oxo-dGuo was observed in H358 cell DNA after treatment with MMS. At low levels of oxidative DNA damage, there was an excellent correlation between a comet assay that measured DNA single strand breaks (SSBs) after treatment with human 8-oxo-guanine glycosylase-1 (hOGG1) when compared with 8-oxo-dGuo in the DNA as measured by the stable isotope dilution LC-MRM/MS method. Availability of the new LC-MRM/MS assay made it possible to show that the benzo[a]pyrene (B[a]P)-derived quinone, B[a]P-7,8-dione, could induce 8-oxo-dGuo formation in H358 cells. This most likely occurred through redox cycling between B[a]P-7,8-dione and B[a]P-7,8-catechol with concomitant generation of DNA damaging ROS. In keeping with this concept, inhibition of catechol-O-methyl transferase (COMT)-mediated detoxification of B[a]P-7,8-catechol with Ro 410961 caused increased 8-oxo-dGuo formation in the H358 cell DNA.

A BRCA1 mutation is not associated with increased indicators of oxidative stress

BACKGROUND

Several functions have been attributed to the BRCA1 protein. A recent study suggests that BRCA1 is involved in the cellular antioxidant response by inducing the expression of genes involved in the antioxidant defense system and thus conferring resistance to oxidative stress. It is possible that individuals with a BRCA1 mutation might be susceptible to the effects of oxidative stress. The aim of this study was to evaluate whether women with a BRCA1 mutation exhibit increased indicators of oxidative stress.

PATIENTS AND METHODS

We measured 3 markers of oxidative stress in vivo, the amounts of serum malondialdehyde and protein thiols, and 8-oxo-2'-deoxyguanosine (8-oxodG) levels in 25 unaffected BRCA1 mutation carriers and 25 noncarrier control subjects.

RESULTS

There was no significant difference in serum malondialdehyde levels (P=.41), serum thiol levels (P=.85), or the number of 8-oxodG lesions (P=.49) in BRCA1 mutation carriers versus noncarriers.

CONCLUSION

The results of this study suggest that the presence of a heterozygous BRCA1 mutation is not associated with increased levels of indicators of oxidative stress in serum or lymphocytes. Future studies are warranted to evaluate whether strategies aimed at minimizing oxidative stress might aid in the prevention of hereditary breast cancer.

Source apportionment of in vitro reactive oxygen species bioassay activity from atmospheric particulate matter

Recent atmospheric particulate matter health studies have suggested that the redox activity is an important factor in particulate matter toxicology, and that reactive oxygen species (ROS) activity may be an important characteristic of particulate matter that is associated with adverse health effects. In this study, associations between atmospheric particulate matter sources and in vitro ROS activities are investigated. Ambient concentrations of fine particle water-soluble elements and total organic and elemental carbon were measured daily in Denver for the 2003 calendar year. The data were used in a multivariate factor analysis source apportionment model, positive matrix factorization (PMF), to determine the contributions of nine sources or factors: a mobile source factor, a water soluble carbon factor, a sulfate factor, a soil dust source, an iron source, two point sources characterized by water soluble toxic metals, a pyrotechnique factor, and a platinum group metal factor. Aqueous leachates, including water soluble and colloidal components, as well as insoluble particles that pass through a 0.2 microm pore size filter, of 45 randomly selected PM samples, were assayed to quantify ROS activity using an in vitro rat alveolar macrophage assay. Results show that PM-stimulated in vitro ROS production was significantly positively correlated with the contributions from three sources: the iron source, the soil dust source and the water soluble carbon factor. The iron source accounted for the greatest fraction of the measured variability in redox activity, followed by the soil dust and the water-soluble carbon factor. Seventy-seven percent of the in vitro ROS activity was explained by a linear combination of these three source contributions.

The sensitivity of pancreatic β-cells to mitochondrial injuries triggered by lipotoxicity and oxidative stress

Pancreatic β-cells are essential for the maintenance of glucose homoeostasis, and dysfunction of these insulin-secreting cells results in the development of diabetes. In the course of events leading from obesity to Type 2 diabetes, several mechanisms are currently envisaged. Among them, lipids and oxidative stress are considered as toxic candidates for the β-cell. The cellular link between fatty acids and ROS (reactive oxygen species) is essentially the mitochondrion, a key organelle for the control of insulin secretion. Mitochondria are the main source of ROS and are also the primary target of oxidative attacks. The present review presents the current knowledge of lipotoxicity related to oxidative stress in the context of mitochondrial function in the β-cell.

Antioxidant effects of phlorotannins isolated from Ishige okamurae in free radical mediated oxidative systems

Three phlorotannins, including phloroglucinol, diphlorethohydroxycarmalol, and 6,6'-bieckol, were isolated from Ishige okamurae by column chromatography. The structures of the phlorotannins were determined on the basis of spectroscopic analysis, including NMR and mass spectrometry (MS) techniques. Antioxidant effects of phlorotannins were measured by direct free radical scavenging activities using the electron spin resonance spectrometry (ESR) technique and cellular systems in vitro. The results indicated that diphlorethohydroxycarmalol and 6,6'-bieckol showed potential radical scavenging activities against the 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl, alkyl, and superoxide radicals. Moreover, no cytotoxicities of the phlorotannins on human fetal lung fibroblasts cell line (MRC-5), mouse macrophages cell line (RAW264.7), and human leukemic cell line (HL-60) were observed. In addition, diphlorethohydroxycarmalol and 6,6'-bieckol significantly reduced the intracellular reactive oxygen species level assessed by 2',7'-dichlorofluorescein diacetate (DCFH-DA) assay in RAW264.7 cells, and myeloperoxide (MPO) activity in HL-60 cells and radical-mediated oxidation of cell membrane proteins in RAW264.7 cells were dose-dependently inhibited in the presence of diphlorethohydroxycarmalol and 6,6'-bieckol. In conclusion, these results suggested that phlorotannins could be used as novel functional foodstuffs or antioxidants in the cosmetic and drug industries.

Zinc in human health: effect of zinc on immune cells

Although the essentiality of zinc for plants and animals has been known for many decades, the essentiality of zinc for humans was recognized only 40 years ago in the Middle East. The zinc-deficient patients had severe immune dysfunctions, inasmuch as they died of intercurrent infections by the time they were 25 years of age. In our studies in an experimental human model of zinc deficiency, we documented decreased serum testosterone level, oligospermia, severe immune dysfunctions mainly affecting T helper cells, hyperammonemia, neurosensory disorders, and decreased lean body mass. It appears that zinc deficiency is prevalent in the developing world and as many as two billion subjects may be growth retarded due to zinc deficiency. Besides growth retardation and immune dysfunctions, cognitive impairment due to zinc deficiency also has been reported recently. Our studies in the cell culture models showed that the activation of many zinc-dependent enzymes and transcription factors were adversely affected due to zinc deficiency. In HUT-78 (T helper 0 [Th(0)] cell line), we showed that a decrease in gene expression of interleukin-2 (IL-2) and IL-2 receptor alpha(IL-2Ralpha) were due to decreased activation of nuclear factor-kappaB (NF-kappaB) in zinc deficient cells. Decreased NF-kappaB activation in HUT-78 due to zinc deficiency was due to decreased binding of NF-kappaB to DNA, decreased level of NF-kappaB p105 (the precursor of NF-kappaB p50) mRNA, decreased kappaB inhibitory protein (IkappaB) phosphorylation, and decreased Ikappa kappa. These effects of zinc were cell specific. Zinc also is an antioxidant and has anti-inflammatory actions. The therapeutic roles of zinc in acute infantile diarrhea, acrodermatitis enteropathica, prevention of blindness in patients with age-related macular degeneration, and treatment of common cold with zinc have been reported. In HL-60 cells (promyelocytic leukemia cell line), zinc enhances the up-regulation of A20 mRNA, which, via TRAF pathway, decreases NF-kappaB activation, leading to decreased gene expression and generation of tumor necrosis factor-alpha (TNF-alpha), IL-1beta, and IL-8. We have reported recently that in both young adults and elderly subjects, zinc supplementation decreased oxidative stress markers and generation of inflammatory cytokines.

Zinc in human health: effect of zinc on immune cells

Although the essentiality of zinc for plants and animals has been known for many decades, the essentiality of zinc for humans was recognized only 40 years ago in the Middle East. The zinc-deficient patients had severe immune dysfunctions, inasmuch as they died of intercurrent infections by the time they were 25 years of age. In our studies in an experimental human model of zinc deficiency, we documented decreased serum testosterone level, oligospermia, severe immune dysfunctions mainly affecting T helper cells, hyperammonemia, neurosensory disorders, and decreased lean body mass. It appears that zinc deficiency is prevalent in the developing world and as many as two billion subjects may be growth retarded due to zinc deficiency. Besides growth retardation and immune dysfunctions, cognitive impairment due to zinc deficiency also has been reported recently. Our studies in the cell culture models showed that the activation of many zinc-dependent enzymes and transcription factors were adversely affected due to zinc deficiency. In HUT-78 (T helper 0 [Th(0)] cell line), we showed that a decrease in gene expression of interleukin-2 (IL-2) and IL-2 receptor alpha(IL-2Ralpha) were due to decreased activation of nuclear factor-kappaB (NF-kappaB) in zinc deficient cells. Decreased NF-kappaB activation in HUT-78 due to zinc deficiency was due to decreased binding of NF-kappaB to DNA, decreased level of NF-kappaB p105 (the precursor of NF-kappaB p50) mRNA, decreased kappaB inhibitory protein (IkappaB) phosphorylation, and decreased Ikappa kappa. These effects of zinc were cell specific. Zinc also is an antioxidant and has anti-inflammatory actions. The therapeutic roles of zinc in acute infantile diarrhea, acrodermatitis enteropathica, prevention of blindness in patients with age-related macular degeneration, and treatment of common cold with zinc have been reported. In HL-60 cells (promyelocytic leukemia cell line), zinc enhances the up-regulation of A20 mRNA, which, via TRAF pathway, decreases NF-kappaB activation, leading to decreased gene expression and generation of tumor necrosis factor-alpha (TNF-alpha), IL-1beta, and IL-8. We have reported recently that in both young adults and elderly subjects, zinc supplementation decreased oxidative stress markers and generation of inflammatory cytokines.

Zinc supplementation decreases oxidative stress, incidence of infection, and generation of inflammatory cytokines in sickle cell disease patients

Zinc deficiency is common in adult sickle-cell disease (SCD) patients. We previously demonstrated that zinc supplementation to adult SCD patients decreased the incidences of infections and hospital admissions. We hypothesize that zinc supplementation improves T-helper cell function and decreases vascular endothelial cell activation, oxidative stress, and nuclear factor-kappa B (NF-kappaB)-DNA binding in mononuclear cells (MNCs) in SCD patients. To test this hypothesis, 36 SCD patients were recruited and randomly divided into 2 groups. One group (n = 18) received 25-mg zinc orally thrice a day for 3 months. The other group (n = 18) received placebo. The results indicate that the zinc-supplemented group had decreased incidence of infections compared with the placebo group. After zinc supplementation, red blood cell, hemoglobin (Hb), hematocrit, (Hct), plasma zinc, and antioxidant power increased; plasma nitrite and nitrate (NOx), lipid peroxidation products, DNA oxidation products, and soluble vascular cell adhesion molecule-1 decreased in the zinc-supplemented group, compared with the placebo group. Zinc-supplemented patients exhibited significant decreases in lipopolysaccharide-induced tumor necrosis factor-alpha (TNF-alpha) and IL-1beta mRNAs, and TNF-induced nuclear factor of kappaB-DNA binding in MNCs, compared with the placebo group. Ex vivo addition of zinc to MNCs isolated from the placebo subjects decreased TNF-alpha and IL-1beta mRNAs. Zinc supplementation also increased relative levels of IL-2 and IL-2Ralpha mRNAs in phytohemagglutinin-p-stimulated MNCs. These results suggest that zinc supplementation may be beneficial to SCD patients.

Clinical, immunological, anti-inflammatory and antioxidant roles of zinc

The essentiality of zinc for humans was recognized only 40 years ago. Zinc deficiency was suspected to occur in Iranian patients with growth retardation, hypogonadism in males, hepato-splenomegaly, rough and dry skin, geophagia and severe iron deficiency anemia. Later we documented zinc deficiency in similar patients in Egypt. The diet of these patients consisted of mainly cereal proteins which contained high phytate and this led to decreased availability of iron and zinc. These patients had severe immune dysfunctions, inasmuch as they died of intercurrent infections by the time they were 25 years of age. In our studies in experimental human model of zinc deficiency, we documented decreased serum testosterone level, oligospermia, severe immune dysfunctions mainly affecting T helper cells, decreased serum thymulin activity hyperammonemia, neuro-sensory disorders and decreased lean body mass. The basic mechanisms of zinc action on immune cells have been reviewed in this paper. Our studies showed that the activation of many zinc dependent enzymes and transcription factors were affected adversely due to zinc deficiency. The gene expression and production of Th1 cytokines were affected adversely due to zinc deficiency. Zinc is also an antioxidant and has anti-inflammatory actions. We have reported decreased plasma zinc, increased plasma oxidative stress markers and increased generation of inflammatory cytokines in the elderly subjects which were corrected by zinc supplementation. In cell culture studies, we have observed that zinc induces A20 which inhibits NF-kappaB activation resulting in decreased generation of inflammatory cytokines.

Effect of monosodium glutamate on oxidative stress and apoptosis in rat thymus

It has been demonstrated that administration of high concentrations of monosodium glutamate (MSG), induce oxidative stress in different organs, but not in thymus. In the present study we examined the role of oxidative stress in MSG-induced thymocyte apoptosis. MSG was administrated intraperitoneally (4 mg/g of body weight) for six consecutive days. Animals were sacrificed at 1st, 7th, and 15th day after last MSG dose. MSG administration to animals significantly increased apoptotic rate of thymocytes (P < 0.01), together with significant increase of malondialdehyde (MDA) level (P < 0.001) and xanthine oxidase (XO) activity (P < 0.01), in time dependent manner. Catalase activity, during examination period, was significantly decreased (0 < 0.01). Obtained results showed that MSG treatment induced oxidative stress in thymus, which may have an important role in thymocyte apoptosis induced by MSG.

Effects of salvianolic acid a on oxidative stress and liver injury induced by carbon tetrachloride in rats

In the present study, we investigated the hepatoprotective effects of salvianolic acid A, a novel antioxidant, against oxidative stress and acute liver injury induced by carbon tetrachloride (CCl(4)) in rats, and the mechanisms underlying its protective effects. Administration of CCl(4) to rats caused severe hepatic damage, as demonstrated by the significant increase in the levels of serum alanine aminotransferase, aspartate aminotransferase and classic histological changes including hepatocyte necrosis or apoptosis, haemorrhage, fatty degeneration, etc. Co-treatment with salvianolic acid A (20 mg/kg, intraperitoneally), a water-soluble extract from a Chinese traditional drug, Radix Salvia miltiorrhiza, significantly decreased CCl(4)-induced hepatotoxicity. Salvianolic acid A not only decreased serum alanine aminotransferase, aspartate aminotransferas levels and ameliorated histopathological manifestations in CCl(4)-treated rats, but also reduced oxidative stress, as evidenced by decreased reactive oxygen species production and malondialdehyde concentrations in the liver tissues, combined with elevated hepatic superoxide dismutase activity and gluthathione content. In addition, salvianolic acid A treatment remarkably reduced intrahepatic tumour necrosis factor-alpha concentrations and caspase-3 activities as compared with the CCl(4)-treated rats. The results suggested that treatment with salvianolic acid A provides a potent protective effect against acute hepatic damage caused by CCl(4) in rats, which may mainly be related to its antioxidative effect.

A review of the interaction among dietary antioxidants and reactive oxygen species

During normal cellular activities, various processes inside of cells produce reactive oxygen species (ROS). Some of the most common ROS are hydrogen peroxide (H(2)O(2)), superoxide ion (O(2)(-)), and hydroxide radical (OH(-)). These compounds, when present in a high enough concentration, can damage cellular proteins and lipids or form DNA adducts that may promote carcinogenic activity. The purpose of antioxidants in a physiological setting is to prevent ROS concentrations from reaching a high-enough level within a cell that damage may occur. Cellular antioxidants may be enzymatic (catalase, glutathione peroxidase, superoxide dismutase) or nonenzymatic (glutathione, thiols, some vitamins and metals, or phytochemicals such as isoflavones, polyphenols, and flavanoids). Reactive oxygen species are a potential double-edged sword in disease prevention and promotion. Whereas generation of ROS once was viewed as detrimental to the overall health of the organism, advances in research have shown that ROS play crucial roles in normal physiological processes including response to growth factors, the immune response, and apoptotic elimination of damaged cells. Notwithstanding these beneficial functions, aberrant production or regulation of ROS activity has been demonstrated to contribute to the development of some prevalent diseases and conditions, including cancer and cardiovascular disease (CVD). The topic of antioxidant usage and ROS is currently receiving much attention because of studies linking the use of some antioxidants with increased mortality in primarily higher-risk populations and the lack of strong efficacy data for protection against cancer and heart disease, at least in populations with adequate baseline dietary consumption. In normal physiological processes, antioxidants effect signal transduction and regulation of proliferation and the immune response. Reactive oxygen species have been linked to cancer and CVD, and antioxidants have been considered promising therapy for prevention and treatment of these diseases, especially given the tantalizing links observed between diets high in fruits and vegetables (and presumably antioxidants) and decreased risks for cancer.

Zinc supplementation decreases incidence of infections in the elderly: effect of zinc on generation of cytokines and oxidative stress

BACKGROUND

Zinc deficiency, cell-mediated immune dysfunction, susceptibility to infections, and increased oxidative stress have been observed in elderly subjects (ie, those >55 y old). Zinc is an effective antiinflammatory and antioxidant agent.

OBJECTIVES

The primary objective was to determine the effect of zinc on the incidence of total infections in healthy elderly subjects. The secondary objective was to determine the effect of zinc on cytokines and oxidative stress markers.

DESIGN

A randomized, double-blind, placebo-controlled trial of zinc supplementation was conducted in elderly subjects. Fifty healthy subjects of both sexes aged 55-87 y and inclusive of all ethnic groups were recruited for this study from a senior center. The zinc-supplemented group received zinc gluconate (45 mg elemental Zn/d) orally for 12 mo. Incidence of infections during the supplementation period was documented. The generation of inflammatory cytokines, T helper 1 and T helper 2 cytokines, and oxidative stress markers and the plasma concentrations of zinc were measured at baseline and after supplementation.

RESULTS

Compared with a group of younger adults, at baseline the older subjects had significantly lower plasma zinc, higher ex vivo generation of inflammatory cytokines and interleukin 10, and higher plasma oxidative stress markers and endothelial cell adhesion molecules. The incidence of infections and ex vivo generation of tumor necrosis factor alpha and plasma oxidative stress markers were significantly lower in the zinc-supplemented than in the placebo group. Plasma zinc and phytohemagglutin-induced interleukin 2 mRNA in isolated mononuclear cells were significantly higher in the zinc-supplemented than in the placebo group.

CONCLUSIONS

After zinc supplementation, the incidence of infections was significantly lower, plasma zinc was significantly higher, and generation of tumor necrosis factor alpha and oxidative stress markers was significantly lower in the zinc-supplemented than in the placebo group.

Protective effects of echinacoside on carbon tetrachloride-induced hepatotoxicity in rats

The aim of this study was to investigate the possible protective effects of echinacoside, one of the phenylethanoids isolated from the stems of Cistanches salsa, a Chinese herbal medicine, on the free radical damage of liver caused by carbon tetrachloride in rats. Treatment of rats with carbon tetrachloride produced severe liver injury, as demonstrated by dramatic elevation of serum ALT, AST levels and typical histopathological changes including hepatocyte necrosis or apoptosis, haemorrhage, fatty degeneration, etc. In addition, carbon tetrachloride administration caused oxidative stress in rats, as evidenced by increased reactive oxygen species (ROS) production and MDA concentrations in the liver of rats, along with a remarkable reduction in hepatic SOD activity and GSH content. However, simultaneous treatment with echinacoside (50mg/kg, intraperitoneally) significantly attenuated carbon tetrachloride-induced hepatotoxicity. The results showed that serum ALT, AST levels and hepatic MDA content as well as ROS production were reduced dramatically, and hepatic SOD activity and GSH content were restored remarkably by echinacoside administration, as compared to the carbon tetrachloride-treated rats. Moreover, the histopathological damage of liver and the number of apoptotic hepatocytes were also significantly ameliorated by echinacoside treatment. It is therefore suggested that echinacoside can provide a definite protective effect against acute hepatic injury caused by CCl(4) in rats, which may mainly be associated with its antioxidative effect.

Analysis of the thiol status of peripheral blood leukocytes in rheumatoid arthritis patients

Although the exact etiology of rheumatoid arthritis (RA) remains unknown, there is increasing evidence that reactive oxygen species and a pro-oxidant/antioxidant imbalance are an important part of the pathogenesis of joint tissue injury. Flow cytometry was used to evaluate the thiol status [surface-thiols and intracellular glutathione (iGSH)] of leukocytes from RA patients and controls. Levels of surface-thiols and iGSH of leukocytes from RA patients were significantly lower than of leukocytes from controls. CD53, a glycoprotein of the tetraspanin superfamily, which coprecipitates with the GSH recycling enzyme gamma-glutamyl transpeptidase, was elevated significantly on leukocytes from RA patients compared with leukocytes from controls. Surface-thiols and GSH play important roles in redox buffering of cells, providing protection from oxidative stress. The chronic inflammation of RA has been associated with oxidative stress, which is shown to cause a decline in the levels of cellular antioxidant sulfhydryls (R-SH). As antioxidant-protective levels also decline with age, the problem is compounded in older RA patients, who did have fewer R-SH. Chronic stress can also have an effect on telomere lengths, determining cell senescence and longevity. Although telomeres shorten with increasing age, our flow cytometry studies indicate that accelerated shortening in telomere lengths occurs with increasing age of RA patients, suggesting premature cellular aging. The paradox is that lymphocytes from RA patients are believed to resist apoptosis, and we suggest that the elevated expression of CD53, which results from the increased oxidative stress, may protect against apoptosis.

Necrotic death without mitochondrial dysfunction-delayed death of cardiac myocytes following oxidative stress

Oxidative stress has been implicated in cell death in range of disease states including ischemia/reperfusion injury of the heart and heart failure. Here we have investigated the mechanisms of cell death following chronic exposure of cardiac myocytes to oxidative stress initiated by hydrogen peroxide. This exposure induced a delayed form of cell death with ultrastructural changes typical of necrosis, and that was accompanied by the release of lactate dehydrogenase and increased lipid peroxidation. However, this delayed death was not accompanied by the loss of mitochondrial membrane potential or caspase-3 activation. Furthermore, we could demonstrate that this delayed necrosis was at least partially prevented by pre-treatment with the hypertrophic stimuli endothelin-1 or leukemic inhibitory factor. Our results suggest that this delayed form necrosis may also comprise an ordered series of events involving pathways amenable to therapeutic modulation.

Vitamin E Protects Against Oxidative Damage Caused by Formaldehyde in the Liver and Plasma of Rats

It is well known that formaldehyde (FA) and reactive oxygen species (ROS) are cytotoxic and potentially carcinogenic. Although the individual effects of these reactants on cells have been investigated, the cytotoxicity exerted by the coexistence of FA and ROS is poorly understood. The present study was carried out to evaluate oxidant/antioxidant status and biochemical changes occurring after chronic formaldehyde toxicity in liver tissue and plasma of rats and protective effect of vitamin E (vit E) against oxidative damage. Eighteen rats were divided into three groups: (1) control rats, (2) rats treated with FA (FAt), and (3) rats treated with FA plus vit E (FAt + vit E) groups. After the treatment, the animals were sacrificed and liver tissues were removed for biochemical investigations. As a result, FA treatment significantly increased the levels of tissue malondialdehyde (MDA), protein carbonyl (PC), nitric oxide (NO) and the activity of xanthine oxidase enzyme (XO). On the other hand, FA exposure led to decrease in superoxide dismutase (SOD) and catalase (CAT) activities in liver tissues compared to control. FA caused significant decreases in total protein (TP) and albumin (ALB) whereas increases in aspartate transaminase (AST), alanine aminotransferase (AST), alkaline phosphatase (ALP) and interleukine-2 (IL-2) levels in plasma. Vit E treatment abolished these changes at a level similar to the control group. It was concluded that vit E treatment might be beneficial in preventing FA-induced liver tissue damage, and therefore have potential for clinical use.

Towards a dietary prevention of hereditary breast cancer

Inheritance of a deleterious mutation in BRCA1 or BRCA2 confers a high lifetime risk of developing breast cancer. Variation in penetrance between individuals suggests that factors other than the gene mutation itself may influence the risk of cancer in susceptible women. Several risk factors have been identified which implicate estrogen-induced growth stimulation as a probable contributor to breast cancer pre-disposition. The protein products of both of these genes appear to help preserve genomic integrity via their participation in the DNA damage response and repair pathways. To date, the evidence for a cancer-protective role of dietary nutrients, for the most part those with antioxidant properties, has been based on women without any known genetic pre-disposition and it is important to identify and evaluate dietary factors which may modify the risk of cancer in BRCA carriers. Here we propose that diet modification may modulate the risk of hereditary breast cancer by decreasing DNA damage (possibly linked to estrogen exposure) or by enhancing DNA repair. The prevention of hereditary breast cancer through diet is an attractive complement to current management strategies and deserves exploration.

Cytotoxic effect of formaldehyde with free radicals via increment of cellular reactive oxygen species

It is well known that formaldehyde (HCHO) and reactive oxygen species (ROS), such as free radicals, are cytotoxic as well as potentially carcinogenic. Although the individual effects of these reactants on cells have been investigated, the cytotoxicity exerted by the coexistence of HCHO and reactive radicals is poorly understood. The present study using Jurkat cells demonstrated that the coexistence of HCHO with water-soluble radical initiator, 2,2'-azobis-[2-(2-imidazolin-2-yl)propane] dihydrochloride (AIPH) dramatically decreased cell viability, and that under such conditions scant cell death was observable induced by either of the reactants alone. Based on the results of phosphatidylserine exposure and caspase activation, this observed cell death, in fact, was apparently necrotic rather than apoptotic. To understand the mechanisms of the cell toxicity of HCHO and AIPH, we assessed two kinds of oxidative stress markers such as cellular glutathione (GSH) content and cellular ROS, and the DNA-protein cross-links, which formed as the result of HCHO treatment. A marked decrease in total cellular GSH was observed not only in the case of the coexistence conditions but also with AIPH alone. Dichlorodihydrofluorescein (DCF) assay revealed that cellular ROS were synergistically increased before cell death. The formation of DNA-protein cross-links was observed in the presence of HCHO and AIPH, and the extent was similar to HCHO alone. Co-incubation with semicarbazide, which inactivates HCHO, prevented this cell death induced by a combination of HCHO and AIPH. Semicarbazide also exhibited an inhibitory effect on the synergistic increment of cellular ROS and the formation of DNA-protein cross-links. These results suggest that the free radicals from AIPH induced GSH reduction, while HCHO resulted in the formation of DNA-protein cross-links, eventuating in a synergistic, incremental increase of cellular ROS and cell death brought about by this combination.

Antioxidant effect of zinc in humans

Oxidative stress is known to be an important contributing factor in many chronic diseases. We tested the hypothesis that in healthy normal volunteers zinc acts as an effective anti-inflammatory and antioxidant agent. Ten normal volunteers were administered daily oral zinc supplementation (45 mg zinc as gluconate) and 10 volunteers received placebo for 8 weeks. Plasma zinc, MDA, HAE, and 8-OHdG levels; LPS-induced TNF-alpha and IL-1beta mRNA; and ex vivo TNF-alpha-induced NF-kappaB activity in mononuclear cells (MNC) were determined before and after supplementation. In subjects receiving zinc, plasma levels of lipid peroxidation products and DNA adducts were decreased, whereas no change was observed in the placebo group. LPS-stimulated MNC isolated from zinc-supplemented subjects showed reduced mRNA for TNF-alpha and IL-1beta compared to placebo. Ex vivo, zinc protected MNC from TNF-alpha-induced NF-kappaB activation. In parallel studies using HL-60, a promyelocytic cell line, we observed that zinc enhances the upregulation of mRNA and DNA-specific binding for A20, a transactivating factor which inhibits the activation of NF-kappaB. Our results suggest that zinc supplementation may lead to downregulation of the inflammatory cytokines through upregulation of the negative feedback loop A20 to inhibit induced NF-kappaB activation. Zinc administration to human subjects with conditions associated with increased oxidative stress should be explored.

Mitochondrial metabolism underlies hyperoxic cell damage

Exposure of mammals to hyperoxia causes pulmonary and ocular pathology. Hyperoxic damage and cell death may derive from enhanced intracellular formation of reactive oxygen species (ROS), probably of mitochondrial origin. There is, however, controversy on this point. When wild-type and respiration-deficient (rho(o)) HeLa cells were cultured in 80% O2, wild-type cells stopped growing after 5 days and died thereafter whereas rho(o) cells survived and grew to confluence. This tolerance of rho(o) cells for hyperoxia was not associated with greater resistance to oxidants such as hydrogen peroxide and t-butyl hydroperoxide. Under both 20% and 80% O2, rho(o) cells exhibited substantially decreased ROS production, and, under 80% O2, rho(o) cells showed no suppression of aconitase activity or mitochondrial protein carbonyl formation. Replacement of normal mitochondria in rho(o) cells restored ROS production and susceptibility to hyperoxia. Two other approaches that diminished mitochondrial ROS generation also increased tolerance for hyperoxia. HeLa cells constantly exposed to the protonophoric uncoupler carbonyl cyanide m-chlorophenylhydrazone, which enhances respiration but decreases ROS production, showed preferential survival under 80% O2, as did HeLa cells treated with chloramphenicol, which suppresses both respiration and mitochondrial ROS production. We conclude that interactions between respiring mitochondria and O2 are primarily responsible for hyperoxic cell damage.

Effect of chlorophyllin against oxidative stress in splenic lymphocytes in vitro and in vivo

Chlorophyllin (CHL) has been examined as an antioxidant/radioprotector in splenic lymphocytes from BALB/c mice. CHL inhibited lipid peroxidation induced by 2,2'-azobis(2-propionimidinedihydrochloride) (AAPH) in lymphocytes in vitro. It also partially prevented radiation-induced suppression of mitogenic stimulation of lymphocytes in vitro. Generation of intracellular reactive oxygen species (ROS) by radiation or AAPH was measured as oxidation of dichlorodihydrofluorescein diacetate (H(2)DCF-DA) using flow cytometry. Addition of CHL to lymphocytes in vitro significantly inhibited the increase in intracellular ROS. Further, lymphocytes from mice treated with CHL (100-400 microg/gbw i. p.) showed varying levels of ROS depending on the dose and the time (24 to 72 h) after injection. The extent of radiation-induced apoptosis and suppression of concanavalin A (con A)-induced mitogenesis ex vivo corresponded with changes in ROS levels in CHL-administered mice. Antioxidant enzymes superoxide dismutase (SOD), catalase and glutathione peroxidase (GPX) were also estimated in lymphocytes from CHL-treated mice. CHL offered protection against whole body irradiation (WBI)-induced lipid peroxidation and apoptosis in lymphocytes at all the time points studied. These results demonstrate antioxidant effect of CHL in vivo.