Is cannabidiol hepatotoxic or hepatoprotective: A review

Questions have been raised regarding the potential hepatotoxicity of cannabidiol (CBD). Conversely, several animal studies have demonstrated the hepatoprotective effects of CBD against bile duct ligation, cocaine, thioacetamide, alcohol, and several other chemicals. This review summarizes the current literature concerning the hepatic effects of CBD in humans and animals. Based on the available data, it may be concluded that there is a low probability of serious hepatotoxicity at the high therapeutic doses that are used and a much lower risk of adverse hepatic effects and a potential for hepatoprotection effects at the lower doses commonly used in dietary supplements and food products. However, a detailed safety study in rats using highly purified CBD rather than enriched Cannabis extracts is needed, enabling the determination of hepatic as well as other tissue effects and potential margin of safety.

Citrus aurantium (bitter orange) extract: Safety assessment by acute and 14-day oral toxicity studies in rats and the Ames Test for mutagenicity

The primary active constituent in bitter orange extract (BOE) is p-synephrine. This study assessed the safety of a BOE standardized to 50% p-synephrine following short-term exposure to rats and by the Ames Test. Following 5000 mg/kg of the extract orally to female rats all animals survived. Administration at 2000 mg/kg to female rats for four days yielded no signs of toxicity. Five male and five female rats were administered the BOE at 0, 250, 500, 1000 and 2000 mg/kg/day for 14 days. No significant effects were observed at any dose with respect to body weights, food intake, absolute and relative organ weights, hematology, clinical chemistry, and pathology. Two male rats died after 2000 mg/kg with gastrointestinal impaction at necropsy. During week two of 1000 mg/kg and 2000 mg/kg/day, rats exhibited transient signs of repetitive burrowing of heads in the bedding material (hypoactivity) for about 15 and 45 min, respectively. The no-observed-effect-level (NOEL) was 500 mg/kg/day. The mutagenic potential was assessed at and up to the limit dose of 5000 μg/plate in a Salmonella typhimurium reverse mutation (Ames) test, performed in duplicate as a pre-incubation assay in the presence and absence of metabolic activation (S9). The BOE did not induce an increase in the frequency of revertant colonies at any dose in the five tester strains, and was therefore non-mutagenic.

Safety of a novel botanical extract formula for ameliorating allergic rhinitis

Allergic rhinitis (also known as hay fever) is the most commonly occurring immunological disorder, and it affects 40 million men, women, and children in the United States. Symptomatically, it is an inflammation and irritation of the mucous membranes that line the nose. Allergy is defined as a state of hypersensitivity or hyperimmunity caused by exposure to a particular antigen (allergen) that results in increased reactivity upon subsequent exposure. A novel botanical formulation, Aller-7/NR-A2, was developed for the treatment of allergic rhinitis; it is a combination of medicinal plant extracts from Phyllanthus emblica, Terminalia chebula, Terminalia bellerica, Albizia lebbeck, Piper nigrum, Zingiber officinale, and Piper longum. This novel formulation has demonstrated potent antihistaminic, anti-inflammatory, antispasmodic, antioxidant, and mast-cell-stabilization activities. All of the doses for these toxicity studies were selected according to the guidelines of the Organization for Economic Cooperation and Development, the World Health Organization, and the Environmental Protection Agency. Acute toxicity of Aller-7 was evaluated in Swiss Albino mice at doses of 125, 250, 500, 1000, and 1500 mg/kg. After 15 days of treatment, the animals were sacrificed. No histopathological changes were observed in major vital organs. A similar study was conducted in Albino Wistar rats, which were sacrificed at the end of 15 days. No histopathological changes or toxicity was observed at up to 2 g/kg body weight. Subacute toxicity was conducted in Albino Wistar rats at a dose of 90 mg/kg body weight for 3 days, then at 180 mg/kg for the next 3 days, and then at 270 mg/kg for 3 weeks. After 28 days, the animals were sacrificed and tested; no toxicity was observed. In a subchronic toxicity study, there was no observed adverse effect level at 1 g/kg body weight in rats. In a teratological assay, at doses of 3.0 g/kg (20 times the recommended dose) and 1.8 g/kg, respectively, no visceral or skeletal anomalies were observed in the fetuses. No maternal changes were observed when Aller-7 was administered during gestation and lactation. No evidence of mutagenicity was observed at doses up to 5000 mug per plate of Aller-7 in Salmonella typhimurium cells. The present study evaluated the safety of Aller-7 by conducting several in vitro and in vivo studies. Further studies of the 90-day chronic toxicity of Aller-7 are currently in progress.

Multinutrient supplement containing ephedra and caffeine causes weight loss and improves metabolic risk factors in obese women: a randomized controlled trial

OBJECTIVE

To determine the safety and efficacy of a dietary supplement with a low dose of ephedra and caffeine in overweight/obese premenopausal female subjects.

DESIGN

A 9-month, double-blind, randomized control study compared the efficacy and safety of a dietary supplement with ephedra and caffeine to a control supplement.

SUBJECTS

Sixty-one healthy, premenopausal women with body mass index (BMI) from 27 to 39 kg/m2 were randomly assigned and received a dietary supplement (40 mg/day ephedra alkaloids, 100 mg/day caffeine, high potency mixture of vitamins, minerals, omega-3 fatty acids) or a control supplement for 9 months.

MEASUREMENTS

EFFICACY

changes in body weight, body composition, lipids, insulin, leptin, adiponectin, ghrelin, and self-reports of physical activity, diet and quality of life indices.

SAFETY

blood pressure, heart rate, electrocardiograms, urinalysis, blood histology, serum chemistry measures and self-reported symptoms.

RESULTS

Forty-one women completed the study. The treatment group lost significantly more body weight (-7.18 kg) and body fat (-5.33 kg) than the control group (-2.25 and -0.99 kg, respectively), and showed significant declines in heart rate, serum cholesterol, triglycerides, cholesterol to high-density lipoprotein ratio, glucose, fasting insulin, and leptin. Blood pressure, electrocardiograms, other clinical chemistry measures, blood histology, urinalysis, and self-reported physical activity were similar in the groups. Minor symptoms included dry mouth, insomnia, nervousness and palpitations. The treatment group reported more energy and decreased appetite compared to controls and scored higher on a quality of life domain assessing vitality.

CONCLUSION

A dietary supplement containing a low potency ephedra/caffeine mixture appeared safe and effective in causing loss of weight and body fat, and improving several metabolic parameters, including insulin sensitivity and lipid profiles when tested under physician supervision. Such supplements could be a useful tool to assist with weight loss.

Safety assessment of (-)-hydroxycitric acid and Super CitriMax, a novel calcium/potassium salt

(-)-Hydroxycitric acid (HCA) is a principle constituent (10-30%) of the dried fruit rind of Garcinia cambogia, a plant native to Southeastern Asia. The dried rind has been used for centuries throughout Southeast Asia as a food preservative, flavoring agent and carminative. Extensive experimental studies show that HCA inhibits fat synthesis and reduces food intake. The objective of this review is to systematically review the available safety/toxicity literature on HCA to determine its safety in-use. The primary mechanism of action of HCA appears to be related to its ability to act as a competitive inhibitor of the enzyme ATP-citrate lyase, which catalyzes the conversion of citrate and coenzyme A to oxaloacetate and acetyl coenzyme A (acetyl-CoA), primary building blocks of fatty acid and cholesterol synthesis. Super CitriMax, a novel calcium/potassium-HCA extract (HCA-SX), is considerably more soluble and bioavailable than calcium-based HCA ingredients. Acute oral toxicity studies in animals demonstrate that CitriMax (50% HCA as calcium salt) has a low acute oral toxicity. In a subchronic study in rats, the gavage administration of HCA-SX at doses up to 2500 mg/kg/day for a period of 90 days caused a significant decrease in body weight and reduction in feed consumption without any adverse effects. The structure, mechanism of action, long history of use of HCA and other toxicity studies indicate that HCA-SX is unlikely to cause reproductive or developmental effects. HCA-SX was not mutagenic in the presence or absence of metabolic activation in Ames genotoxicity assays in strains TA98 and TA102. HCA-SX-induced increases in number of revertants in other strains (TA100 and TA1535 in the absence of metabolic activation and in strain TA1537 in the presence of metabolic activation) but these were not considered as biologically indicative of a mutagenic effect. In several, placebo-controlled, double-blind trials employing up to 2800 mg/day HCA, no treatment-related adverse effects were reported. There is sufficient qualitative and quantitative scientific evidence, including animal and human data suggesting that intake of HCA at levels up to 2800 mg/day is safe for human consumption.

Antioxidant properties of Aller-7, a novel polyherbal formulation for allergic rhinitis

Allergic rhinitis, a frequently occurring immunological disorder affecting men, women and children worldwide, is a state of hypersensitivity that occurs when the body overreacts to a substance such as pollen, mold, mites or dust. Allergic rhinitis exerts inflammatory response and irritation of the nasal mucosal membranes leading to sneezing; stuffy/runny nose; nasal congestion; and itchy, watery and swollen eyes. A novel, safe polyherbal formulation (Aller-7/NR-A2) has been developed for the treatment of allergic rhinitis using a unique combination of extracts from seven medicinal plants including Phyllanthus emblica, Terminalia chebula, Terminalia bellerica, Albizia lebbeck, Piper nigrum, Zingiber officinale and Piper longum. In this study, the antioxidant efficacy of Aller-7 was investigated by various assays including hydroxyl radical scavenging assay, superoxide anion scavenging assay, 1,1-diphenyl-2-picryl hydrazyl (DPPH) and 2,2-azinobis-ethyl-benzothiozoline-sulphonic acid diammonium salt (ABTS) radical scavenging assays. The protective effect of Aller-7 on free radical-induced lysis of red blood cells and inhibition of nitric oxide release by Aller-7 in lipopolysaccharide-stimulated murine macrophages were determined. Aller-7 exhibited concentration-dependent scavenging activities toward biochemically generated hydroxyl radicals (IC50 741.73 microg/ml); superoxide anion (IC50 24.65 microg/ml by phenazine methosulfate-nicotinamide adenine dinucleotide [PMS-NADH] assay and IC50 4.27 microg/ml by riboflavin/nitroblue tetrazolium [NBT] light assay), nitric oxide (IC50 16.34 microg/ml); 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical (IC50 5.62 microg/ml); and 2,2-azinobis-ethyl-benzothiozoline-sulphonic acid diammonium salt (ABTS) radical (IC50 7.35 microg/ml). Aller-7 inhibited free radical-induced hemolysis in the concentration range of 20-80 microg/ml. Aller-7 also significantly inhibited nitric oxide release from lipopolysaccharide-stimulated murine macrophages. These results demonstrate that Aller-7 is a potent scavenger of free radicals and that it may serve.

Mast cell stabilization, lipoxygenase inhibition, hyaluronidase inhibition, antihistaminic and antispasmodic activities of Aller-7, a novel botanical formulation for allergic rhinitis

Allergic rhinitis, also known as hay fever, rose fever or summer catarrh, is a major challenge to health professionals. A large number of the world's population, including approximately 40 million Americans, suffers from allergic rhinitis. A novel, botanical formulation (Aller-7) has been developed for the treatment of allergic rhinitis using a combination of extracts from seven medicinal plants, including Phyllanthus emblica, Terminalia chebula, T. bellerica, Albizia lebbeck, Piper nigrum, Zingiber officinale and P. longum, which have a proven history of efficacy and health benefits. The clinical manifestations of allergy are due to a number of mediators that are released from mast cells. The effect of Aller-7 on rat mesenteric mast cell degranulation was studied by incubating different concentrations of Aller-7 and challenging them with a degranulating agent, compound 48/80. The inhibitory activity of Aller-7 was determined against lipoxygenase and hyaluronidase, the key enzymes involved in the initiation and maintenance of inflammatory responses. Furthermore, most of these manifestations are due to histamine, which causes vasodilatation, increasing capillary permeability and leading to bronchoconstriction. Hence, the antihistaminic activity of Aller-7 was determined is isolated guinea pig ileum substrate using cetirizine as a positive control. The antispasmodic effect of Aller-7 on contractions of guinea pig tracheal chain was determined using papaverine and cetirizine as controls. Aller-7 exhibited potent activity in all these in vitro models tested, thus demonstrating the novel anti-allergic potential of Aller-7.

Protective effects of antioxidants against smokeless tobacco-induced oxidative stress and modulation of Bcl-2 and p53 genes in human oral keratinocytes

The oral use of chewing tobacco has greatly increased in recent years, and this usage is associated with cancers of the mouth, lip, nasal cavities, esophagus and gut. Oral cancer accounts for 3% of all cancers in U.S.A. and is the seventh most common cancer. Previous studies in our laboratory have demonstrated the protective abilities of a novel IH636 grape seed proanthocyanidin extract (GSPE) against reactive oxygen species both in vitro and in vivo models, and provided significantly better protection as compared to vitamins C, E and beta-carotene. In the recent past, we have demonstrated smokeless tobacco (STE)-induced oxidative stress, apoptotic cell death in a primary culture of normal human oral keratinocytes (NHOK), and have compared the protective abilities of vitamins C and E, singly and in combination, and GSPE in this pathobiology [Free Rad. Biol. Med., 26, 992-1000 (1999)]. In the present study, we have assessed the protective role of vitamins C and E, and GSPE against STE-induced modulation of intracellular oxidized states in NHOK cells as demonstrated by laser scanning confocal microscopy. Approximately 11%, 26%, 28% and 50% protection were observed following incubation with vitamin C, vitamin E, a combination of vitamins C plus E, and GSPE, respectively. DNA fragmentation was assessed as an index of oxidative DNA damage and similar results were observed. Furthermore, the cellular viability and functional roles of Bcl-2, p53 and c-myc genes were assessed in STE-induced oxidative stress in NHOK cells. NHOK cells were treated with STE (0-200 micrograms/ml) for 24 h and changes in the expression of Bcl-2, p53 and c-myc genes were measured by reverse transcriptase-polymerase chain reaction (RT-PCR), and the protective effect of GSPE was assessed. Approximately a 2.0-fold increase in p53 gene expression was observed following incubation of the oral keratinocytes with 100 micrograms/ml of STE, beyond which the expression of p53 decreased, confirming increased apoptotic cell death with a higher concentration of STE as reported earlier. GSPE significantly modulated STE-induced changes in p53. The expression of antiapoptotic Bcl-2 gene decreased with STE treatment and the expression of Bcl-2 gene increased significantly following preincubation with GSPE. No significant change in the expression of transcription factor c-myc gene responsible for cell cycle growth was observed following incubation with STE and/or GSPE. Thus, c-myc may not be involved in STE-induced cytotoxicity towards NHOK cells. These results suggest that antioxidant protection of STE-induced cellular injury is associated with alterations in Bcl-2 and p53 expression.

Oxidative mechanisms in the toxicity of chromium and cadmium ions

Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities.

Chromium (VI)-induced oxidative stress, apoptotic cell death and modulation of p53 tumor suppressor gene

Chromium (VI) is a widely used industrial chemical, extensively used in paints, metal finishes, steel including stainless steel manufacturing, alloy cast irons, chrome, and wood treatment. On the contrary, chromium (III) salts such as chromium polynicotinate, chromium chloride and chromium picolinate, are used as micronutrients and nutritional supplements, and have been demonstrated to exhibit a significant number of health benefits in rodents and humans. However, the cause for the hexavalent chromium to induce cytotoxicity is not entirely understood. A series of in vitro and in vivo studies have demonstrated that chromium (VI) induces an oxidative stress through enhanced production of reactive oxygen species (ROS) leading to genomic DNA damage and oxidative deterioration of lipids and proteins. A cascade of cellular events occur following chromium (VI)-induced oxidative stress including enhanced production of superoxide anion and hydroxyl radicals, increased lipid peroxidation and genomic DNA fragmentation, modulation of intracellular oxidized states, activation of protein kinase C, apoptotic cell death and altered gene expression. In this paper, we have demonstrated concentration- and time-dependent effects of sodium dichromate (chromium (VI) or Cr (VI)) on enhanced production of superoxide anion and hydroxyl radicals, changes in intracellular oxidized states as determined by laser scanning confocal microscopy, DNA fragmentation and apoptotic cell death (by flow cytometry) in human peripheral blood mononuclear cells. These results were compared with the concentration-dependent effects of chromium (VI) on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Chromium (VI)-induced enhanced production of ROS, as well as oxidative tissue and DNA damage were observed in these cells. More pronounced effect was observed on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Furthermore, we have assessed the effect of a single oral LD50 dose of chromium (VI) on female C57BL/6Ntac and p53-deficient C57BL/6TSG p53 mice on enhanced production of superoxide anion, lipid peroxidation and DNA fragmentation in the hepatic and brain tissues. Chromium (VI)-induced more pronounced oxidative damage in p53 deficient mice. This in vivo study highlighted that apoptotic regulatory protein p53 may play a major role in chromium (VI)-induced oxidative stress and toxicity. Taken together, oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptotic regulatory gene p53 are involved in chromium (VI)-induced toxicity and carcinogenesis.

Production of superoxide anion, lipid peroxidation and DNA damage in the hepatic and brain tissues of rats after subchronic exposure to mixtures of TCDD and its congeners

In this study the induction of oxidative stress in the hepatic and brain tissues of rats after subchronic exposure to various mixtures of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and two of its congeners, namely 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 3,3',4,4',5-pentachlorobiphenyl (PCB 126) was investigated. Four mixtures of TCDD and its congeners, corresponding to 10, 22, 46 and 100 ng of toxic equivalence (TEQ) kg(-1) day(-1), were administered to groups of rats for 13 weeks. The animals were sacrificed at the end of the exposure period and the biomarkers of oxidative stress, including the production of superoxide anion, lipid peroxidation and DNA single-strand breaks (SSBs), were determined in the hepatic and brain tissues. All mixtures caused dose-dependent increases in the production of superoxide anion, lipid peroxidation and DNA SSBs in both tissues, with significantly higher damage in the hepatic compared with the brain tissues. The 22 ng TEQ dose level (TEQ = 22) contains TCDD, PeCDF and PCB 126 at levels that correspond to 7.3, 14.5 and 73.3 ng kg(-1) day(-1), respectively, and it produced effects that correspond to ca. 50% of the maximal production of superoxide anion, lipid peroxidation and DNA SSBs in the hepatic and brain tissues of those animals. Relative to the doses that are required to produce 50% of the maximal production of the biomarkers of oxidative stress by the individual congeners in hepatic and brain tissues of rats, the concentrations of the congeners in TEQ = 22 did result in significant interactivity, probably in the form of additive effects in the hepatic but not in brain tissues.

Protective effect of melatonin on naphthalene-induced oxidative stress and DNA damage in cultured macrophage J774A.1 cells

Naphthalene is a bicyclic aromatic compound that is widely used in various domestic and commercial applications. Previous studies in our laboratory have demonstrated enhanced production of reactive oxygen species, lipid peroxidation and DNA fragmentation in both in vitro and in vivo models following treatment with naphthalene. Melatonin (N-acetyl-5-methoxytryptamine), an indole hormone, is the chief secretory product of the pineal gland and is an efficient free radical scavenger and antioxidant, both in vitro and in vivo. In this study, we have investigated the ability of 1 mM melatonin to protect against naphthalene-induced oxidative stress and DNA damage in cultured macrophage J774A.1 cells. No significant changes were observed when these macrophage cells were treated with 100 microM naphthalene. Approximately 2.0-, 4.2- and 4.4-fold increases in cytochrome c reduction were observed at 200, 400 and 500 mM concentrations of naphthalene, demonstrating the increased production of superoxide anion. At 24 h, lipid peroxidation increased by approximately 1.4-, 2.1- and 2.2-fold following treatment of these cells with 200, 400 and 500 mM concentrations of naphthalene, respectively, while 1.6-, 2.8- and 2.8-fold increases in DNA fragmentation were observed at these same concentrations. Two hour pretreatment of these cultured cells with 1 mM melatonin provided approximately 26-44% decreases in lipid peroxidation, superoxide anion production and DNA fragmentation in cells treated with 400 and 500 microM naphthalene. Cellular viability decreased significantly when cells were incubated with concentrations of naphthalene greater than 100 microM, while preincubation with melatonin significantly increased the cellular viability. These results demonstrate that naphthalene may induce toxic manifestations by enhanced production of reactive oxygen free radicals, resulting in lipid peroxidation and DNA damage, while preincubation with melatonin significantly suppressed cytoxicity in J774A.1 macrophage cells.

Acute and long-term safety evaluation of a novel IH636 grape seed proanthocyanidin extract

Grape seed proanthocyanidins are known to possess a broad spectrum of pharmacological, medicinal and therapeutic properties. Previous studies in our laboratories have demonstrated the various protective abilities of a novel IH636 grape seed proanthocyanidin extract (GSPE) against various pathologic conditions. However no extensive safety studies have been conducted on grape seed proanthocyanidins to date. This study demonstrates the acute and chronic safety studies on GSPE. Acute oral toxicity, dermal toxicity, dermal irritation and eye irritation studies have been conducted. The LD50 of GSPE was found to be greater than 5000 mg/kg when administered once orally via gastric intubation to fasted male and female albino rats. The LD50 of GSPE was found to be greater than 2000 mg/kg when administered once for 24 hr to the clipped, intact skin of male and female albino rats. In addition, 2000 mg/kg was found to be the no-observed-effect level (NOEL) for systemic toxicity under the conditions of the study. In a dermal irritation study, GSPE received a descriptive rating classification of moderately irritating. Extensive chronic studies were also conducted. We have assessed the effects of chronic administration of 100 mg GSPE/kg/day for twelve months and its effect on seven vital target organs, namely, brain, heart, intestine, kidney, liver, lung and spleen, and on serum chemistry changes in male B6C3F1 mice. Furthermore, the dose-dependent chronic effects of GSPE in female B6C3F1 mice were evaluated. Mice were fed 0, 100, 250 or 500 mg GSPE/kg/day for six months and the effects of GSPE exposure were examined on brain, duodenum, heart, kidney, liver, lung, pancreas and spleen, and on serum chemistry changes in female mice. These acute studies demonstrated that GSPE is safe and did not cause any detrimental effects in vivo under the conditions investigated in this study.

The glutathione defense system in the pathogenesis of rheumatoid arthritis

In order to assess a possible role of the natural glutathione defense system in the pathogenesis of rheumatoid arthritis (RA), serum reduced glutathione levels (GSH), glutathione reductase (GSR), glutathione S-transferase (GST), glutathione peroxidase (GSH-Px) and alkaline phosphatase (ALP) activities, lipid peroxidation (MDA content) and indexes of inflammation were evaluated in 58 rheumatic patients. Rheumatoid athritis was associated with significant depletion (ca. 50%) in GSH levels compared with normal control subjects. Serum levels of the detoxifying enzymes GSR and GSH-Px decreased by ca. 50% and 45%, respectively, whereas a threefold increase in the activity of GST was observed. A 1.2-fold increase in ALP was observed in patients with RA. These effects were accompanied by a 3.1-fold increase in serum MDA content. The MDA content was higher in RA patients who were seropositive for rheumatoid factor as well as positive for C-reactive proteins. The erythrocyte sedimentation rate for all patients with RA was approximately 13.8-fold higher than for the control group, and was higher among RA patients who were positive for C-reactive proteins and exhibited seropositivity for rheumatoid factor. Patients with RA receiving gold therapy exhibited significantly lower MDA levels whereas all other factors that were measured were not effected. The results support a hypothesis that defense mechanisms against reactive oxygen species are impaired in RA.

Oxidative mechanisms in the toxicity of chromium and cadmium ions

Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of the oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities.

Cadmium- and chromium-induced oxidative stress, DNA damage, and apoptotic cell death in cultured human chronic myelogenous leukemic K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells

Sodium dichromate [Cr(VI)] and cadmium chloride [Cd(II)] are both cytotoxic and mutagenic. This study examined the toxic and apoptotic potentials of these two cations on three cell types in vitro, namely, human chronic myelogenous leukemic (CML) K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells. The cells were incubated with 0-100 microM concentrations of the two cations for 0, 24, or 48 hours at 37 degrees C. Both Cr(VI) and Cd(II) induced changes in intracellular oxidized states of cells, which were detected using laser scanning confocal microscopy. Cell cycle modulation and apoptosis of the K562 cells by Cr(VI) and Cd(II) were determined by flow cytometry. Significant decreases in the G2/M phase were observed in the Cr(VI) and Cd(II) treated CML cells compared with untreated cells. At 12.5 microM, Cr(VI) induced greater apoptosis in K562 cells as compared with Cd(II). In the K562 cells, 2.2- and 3.0-fold increases in DNA fragmentation were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.2- and 1.7-fold increases in DNA fragmentation were observed with Cd(II). Furthermore, approximately 2.7- and 4.9-fold increases in cytochrome c reduction were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.6- and 3.3-fold increases in cytochrome c reduction were observed with Cd(II), demonstrating enhanced production of superoxide anion. Approximately 3.1 to 6-fold increases in hydroxyl radical production were observed following incubation of the K562 cells with these cations at 12.5 and 25 microM concentrations. These results in K562 cells were compared with promyelocytic leukemic HL-60 cells and normal human peripheral blood mononuclear cells. More pronounced effects were observed on K562 and HL-60 cells, and much lesser effects were observed on normal human peripheral blood mononuclear cells. The results demonstrate that both cations are toxic, producing oxidative tissue damage and apoptosis. Furthermore, more drastic effects were observed on K562 and HL-60 cells as compared with normal human peripheral blood mononuclear cells.

Free radicals and grape seed proanthocyanidin extract: importance in human health and disease prevention

Free radicals have been implicated in over a hundred disease conditions in humans, including arthritis, hemorrhagic shock, atherosclerosis, advancing age, ischemia and reperfusion injury of many organs, Alzheimer and Parkinson's disease, gastrointestinal dysfunctions, tumor promotion and carcinogenesis, and AIDS. Antioxidants are potent scavengers of free radicals and serve as inhibitors of neoplastic processes. A large number of synthetic and natural antioxidants have been demonstrated to induce beneficial effects on human health and disease prevention. However, the structure-activity relationship, bioavailability and therapeutic efficacy of the antioxidants differ extensively. Oligomeric proanthocyanidins, naturally occurring antioxidants widely available in fruits, vegetables, nuts, seeds, flowers and bark, have been reported to possess a broad spectrum of biological, pharmacological and therapeutic activities against free radicals and oxidative stress. We have assessed the concentration- or dose-dependent free radical scavenging ability of a novel IH636 grape seed proanthocyanidin extract (GSPE) both in vitro and in vivo models, and compared the free radical scavenging ability of GSPE with vitamins C, E and beta-carotene. These experiments demonstrated that GSPE is highly bioavailable and provides significantly greater protection against free radicals and free radical-induced lipid peroxidation and DNA damage than vitamins C, E and beta-carotene. GSPE was also shown to demonstrate cytotoxicity towards human breast, lung and gastric adenocarcinoma cells, while enhancing the growth and viability of normal human gastric mucosal cells. The comparative protective effects of GSPE, vitamins C and E were examined on tobacco-induced oxidative stress and apoptotic cell death in human oral keratinocytes. Oxidative tissue damage was determined by lipid peroxidation and DNA fragmentation, while apoptotic cell death was assessed by flow cytometry. GSPE provided significantly better protection as compared to vitamins C and E, singly and in combination. GSPE also demonstrated excellent protection against acetaminophen overdose-induced liver and kidney damage by regulating bcl-X(L) gene, DNA damage and presumably by reducing oxidative stress. GSPE demonstrated excellent protection against myocardial ischemia-reperfusion injury and myocardial infarction in rats. GSPE was also shown to upregulate bcl(2) gene and downregulate the oncogene c-myc. Topical application of GSPE enhances sun protection factor in human volunteers, as well as supplementation of GSPE ameliorates chronic pancreatitis in humans. These results demonstrate that GSPE provides excellent protection against oxidative stress and free radical-mediated tissue injury.

The relative abilities of TCDD and its congeners to induce oxidative stress in the hepatic and brain tissues of rats after subchronic exposure

The abilities of single doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to induce oxidative stress in hepatic and some extra-hepatic tissues of animals, are well documented. In this study we have investigated the induction of oxidative stress in hepatic and brain tissues of rats after subchronic (13 weeks) exposure to TCDD and two of its congeners, namely 2,3,4,7,8-pentachlorodibenzofuran (PeCDF) and 3,3',4,4',5-pentachlorobiphenyl (PCB126). TCDD, PeCDF and PCB126 were administered daily to groups of rats at various doses, for 13 weeks, and biomarkers of oxidative stress, including the production of superoxide anion, lipid peroxidation and DNA-single strand breaks (SSBs), were determined in the hepatic and brain tissues at the end of the exposure period. The three congeners caused dose-dependent increases in the production of superoxide anion, lipid proxidation and DNA-SSBs, with maximal effects achieved at doses ranging between 10-100, 20-92, and 300-550 ng/kg per day for TCDD, PeCDF and PCB126, respectively. The doses that produce 50% of maximal responses by each of the xenobiotics in the hepatic and brain tissues were found to be within the ranges of 7-34, 13-32, and 137-400 ng/kg per day for TCDD, PeCDF and PCB126, respectively. The results of the study suggest that subchronic exposures to TCDD, PeCDF and PCB126 induce significant oxidative damage in the hepatic and brain tissues of rats, with more damage observed in the brain as compared to the hepatic tissues. Also, as inducers of oxidative stress in the hepatic and brain tissues, TCDD is the most potent among the three congeners and PCB126 being the least potent.

Role of p53 tumor suppressor gene in the toxicity of TCDD, endrin, naphthalene, and chromium (VI) in liver and brain tissues of mice

It has been postulated that tumor suppressor genes are involved in the cascade of events leading to the toxicity of diverse xenobiotics. Therefore, we have assessed the comparative effects of 0.01, 0.10, and 0.50 median lethal doses (LD(50)) of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene, and sodium dichromate (VI) [Cr(VI)] on lipid peroxidation, DNA fragmentation, and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of p53-deficient and standard C57BL/6NTac mice to determine the role of p53 gene in the toxic manifestations produced by these diverse xenobiotics. In general, p53-deficient mice are more susceptible to all four xenobiotics than C57BL/6NTac mice, with dose-dependent effects being observed. Specifically, at a 0.50 LD(50) dose, naphthalene and Cr(VI) induced the greatest toxicity in the liver tissue of mice, and naphthalene and endrin exhibited the greatest effect in the brain tissue. At this dose, TCDD, endrin, naphthalene, and Cr(VI) induced 2.3- to 3.7-fold higher increases in hepatic lipid peroxidation and 1.8- to 3.0-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. At a 0. 10 LD(50) dose, TCDD, endrin, naphthalene, and Cr(VI) induced 1.3- to 1.8-fold higher increases in hepatic lipid peroxidation and 1.4- to 1.9-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. Similar results were observed with respect to DNA fragmentation and cytochrome c reduction (superoxide anion production). For example, at the 0.10 LD(50) dose, the four xenobiotics induced increases of 1.6- to 3. 0-fold and 1.5- to 2.1-fold in brain and liver DNA fragmentation, respectively, and increases of 1.5- to 2.3-fold and 1.4- to 2.5-fold in brain and liver cytochrome c reduction (superoxide anion production), respectively, in p53-deficient mice compared with control C57BL/6NTac mice. These results suggest that the p53 tumor suppressor gene may play a role in the toxicity of structurally diverse xenobiotics.

Mechanism of gastroprotection by bismuth subsalicylate against chemically induced oxidative stress in cultured human gastric mucosal cells

Reactive oxygen species (ROS) are implicated in the pathogenesis of chemically induced gastric mucosal injury. We have investigated the effects of ethanol, hydrochloric acid (HCl), and sodium hydroxide (NaOH) on: (1) enhanced production of ROS including superoxide anion and hydroxyl radicals, (2) modulation of intracellular oxidized states by laser scanning confocal microscopy, and (3) DNA fragmentation, indices of oxidative tissue, and DNA damage in a primary culture of normal human gastric mucosal cells (GC), which were isolated and cultured from Helicobacter pylori-negative endoscopic biopsies from human subjects. The induction of ROS and DNA damage in these cells following exposure to ethanol (15%), HCl (150 mM) and NaOH (150 mM) were assessed by cytochrome c reduction (superoxide anion production), HPLC detection for enhanced production of hydroxyl radicals, changes in intracellular oxidized states by laser scanning confocal microscopy, and DNA damage by quantitating DNA fragmentation. Furthermore, the protective ability of bismuth subsalicylate (BSS) was assessed at concentrations of 25, 50, and 100 mg/liter. Incubation of GC with ethanol, HCI, and NaOH increased superoxide anion production by approximately 8.0-, 6.1-and 7.1-fold and increased hydroxyl radical production by 13.3-, 9.6-, and 8.9-fold, respectively, compared to the untreated gastric cells. Incubation of GC with ethanol, HCl, and NaOH increased DNA fragmentation by approximately 6.7-, 4.3-, and 4.8-fold, respectively. Approximately 20.3-, 17.5-, and 13.1-fold increases in fluorescence intensities were observed following incubation of gastric cells with ethanol, HCl, and NaOH, respectively, demonstrating dramatic changes in the intracellular oxidized states of GC following exposure to these necrotizing agents. Preincubation of GC with 25, 50, and 100 mg/liter of BSS decreased ethanol-induced increases in intracellular oxidized states in these cells by 36%, 56%, and 66%, respectively, demonstrating a concentration-dependent protective ability by BSS. Similar results were observed with respect to BSS in terms of superoxide anion and hydroxyl radical production, and DNA damage. The present study demonstrates that ethanol, HCl, and NaOH induce oxidative stress and DNA damage in GC and that BSS can significantly attenuate gastric injury by scavenging these ROS.

The cytotoxic effects of a novel IH636 grape seed proanthocyanidin extract on cultured human cancer cells

Grape seed proanthocyanidins are natural antioxidants which possess a broad spectrum of chemoprotective properties against free radicals and oxidative stress. In this study, we have assessed the cytotoxicity of a novel IH636 grape seed proanthocyanidin extract (GSPE) against MCF-7 human breast cancer cells, A-427 human lung cancer cells, CRL-1739 human gastric adenocarcinoma cells and K562 chronic myelogenous leukemic cells at 25 and 50 mg/lit concentrations for 0-72 h using cytomorphology and MTT cytotoxicity assay. In addition, we compared the effects on normal human gastric mucosal cells and normal J774A.1 murine macrophage cells with the effects on the cancer cell lines. Concentration- and time-dependent cytotoxic effects of GSPE were observed on the MCF-7 breast cancer, A-427 lung cancer and gastric adenocarcinoma cells. Following incubation of the MCF-7 cells with 25 mg/lit of the GSPE approximately 6.5, 30 and 43% inhibitions in cell growth were observed at 24, 48 and 72 h of incubation, respectively, while incubation of the MCF-7 cells with 50 mg/lit of the GSPE resulted in 11, 35 and 47% inhibition in cell growth at these same points, respectively. Similar results were observed in the A-427 and gastric adenocarcinoma cells. GSPE exhibited no cytotoxicity toward the neoplastic K562 myelogenous leukemic cells. However, GSPE enhanced the growth and viability of the normal human gastric mucosal cells and J774A.1 murine macrophage cells. These data demonstrate that GSPE exhibited cytotoxicity towards some cancer cells, while enhancing the growth and viability of the normal cells which were examined.

The cytotoxic effects of a novel IH636 grape seed proanthocyanidin extract on cultured human cancer cells

Grape seed proanthocyanidins are natural antioxidants which possess a broad spectrum of chemoprotective properties against free radicals and oxidative stress. In this study, we have assessed the cytotoxicity of a novel IH636 grape seed proanthocyanidin extract (GSPE) against MCF-7 human breast cancer cells, A-427 human lung cancer cells, CRL-1739 human gastric adenocarcinoma cells and K562 chronic myelogenous leukemic cells at 25 and 50 mg/lit concentrations for 0-72 h using cytomorphology and MTT cytotoxicity assay. In addition, we compared the effects on normal human gastric mucosal cells and normal J774A.1 murine macrophage cells with the effects on the cancer cell lines. Concentration- and time-dependent cytotoxic effects of GSPE were observed on the MCF-7 breast cancer, A-427 lung cancer and gastric adenocarcinoma cells. Following incubation of the MCF-7 cells with 25 mg/lit of the GSPE approximately 6.5, 30 and 43% inhibitions in cell growth were observed at 24, 48 and 72 h of incubation, respectively, while incubation of the MCF-7 cells with 50 mg/lit of the GSPE resulted in 11, 35 and 47% inhibition in cell growth at these same points, respectively. Similar results were observed in the A-427 and gastric adenocarcinoma cells. GSPE exhibited no cytotoxicity toward the neoplastic K562 myelogenous leukemic cells. However, GSPE enhanced the growth and viability of the normal human gastric mucosal cells and J774A.1 murine macrophage cells. These data demonstrate that GSPE exhibited cytotoxicity towards some cancer cells, while enhancing the growth and viability of the normal cells which were examined.

Acute and chronic stress-induced oxidative gastrointestinal mucosal injury in rats and protection by bismuth subsalicylate

Reactive oxygen species (ROS) are implicated in the pathogenesis of stress-induced gastrointestinal mucosal injury. In the present study, we have investigated the effects of acute and chronic stress on the enhanced production of ROS including superoxide anion [SA; as determined by cytochrome c reduction (CCR)] and hydroxyl radicals (OH), and correlated the enhanced production of these free radicals with increased lipid peroxidation, membrane microviscosity and DNA fragmentation, indices of oxidative tissue damage, in the gastric and intestinal mucosa of female Sprague-Dawley rats. Furthermore, the protective ability of bismuth subsalicylate (BSS) against the gastrointestinal mucosal injury induced by acute and chronic stress was determined. Acute stress was induced for a period of 90 min, while chronic stress was induced for 15 min/day for 15 consecutive days. Half of the animals exposed to acute stress were pretreated orally with 15 mg BSS/kg 30 min prior to the exposure to acute stress. Similarly, half of the animals exposed to water-immersion restraint chronic stress were pretreated orally with 7.5 mg BSS/kg/day for 15 consecutive days 30 min prior to the exposure to chronic stress. Acute stress produced greater injury to both gastric and intestinal mucosa as compared to chronic stress. Acute stress increased CCR and OH production by 10.0- and 14.3-fold, respectively, in the gastric mucosa, and 10.4- and 17.0-fold, respectively, in the intestinal mucosa. Pretreatment with BSS prevented the acute stress-induced increase in CCR and OH production. Acute stress increased lipid peroxidation, DNA fragmentation and membrane microviscosity by 3.6-, 4.0- and 11.6-fold, respectively, in gastric mucosa, and 4.1-, 5.0- and 16.2-fold, respectively, in intestinal mucosa. BSS decreased acute stress-induced lipid peroxidation, DNA fragmentation and membrane microviscosity by approximately 26, 35 and 30%, respectively, in gastric mucosa, and by 20, 36 and 30%, respectively, in the intestinal mucosa. Chronic stress increased CCR and OH production by 4.8- and 6.3-fold, respectively, in gastric mucosa, and 4.6- and 6.9-fold, respectively, in intestinal mucosa. Chronic stress increased lipid peroxidation and DNA fragmentation by 2.9- and 3.3-fold, respectively, in gastric mucosa, and 3.3- and 4.2-fold, respectively, in intestinal mucosa. BSS decreased chronic stress-induced lipid peroxidation, DNA fragmentation and membrane microviscosity by approximately 41, 44 and 45%, respectively, in gastric mucosa, and by 39, 52 and 51%, respectively, in the intestinal mucosa. Daily administration of BSS provided greater protection against chronic stress-induced oxidative gastrointestinal injury as compared to the acute stress. These results demonstrate that both acute and chronic stress can induce gastrointestinal mucosal injury through enhanced production of ROS, and that BSS can significantly protect against gastrointestinal mucosal injury.

Smokeless tobacco, oxidative stress, apoptosis, and antioxidants in human oral keratinocytes

We have investigated the effects of a smokeless tobacco extract (STE) on lipid peroxidation, cytochrome c reduction, DNA fragmentation and apoptotic cell death in normal human oral keratinocyte cells, and assessed the protective abilities of selected antioxidants. The cells, isolated and cultured from human oral tissues, were treated with STE (0-300 microl;g/ml) for 24 h. Superoxide anion production was determined by cytochrome c reductase. Oxidative tissue damage was determined by lipid peroxidation and DNA fragmentation, whereas apoptotic cell death was assessed by flow cytometry. STE-induced fragmentation of genomic DNA was also determined by gel electrophoresis. The comparative protective abilities of vitamin C (75 microM), vitamin E (75 microM), a combination of vitamins C & E (75 microM each), and a novel grape seed proanthocyanidin (IH636) extract (GSPE) (100 microg/ml) against STE induced oxidative stress and tissue damage were also determined. Following treatment of the cells with 300 microg STE/ml 1.5-7.6-fold increases in lipid peroxidation, cytochrome c reduction and DNA fragmentation were observed. The addition of the antioxidants to cells treated with STE provided 10-54% decreases in these parameters. Approximately 9, 29, and 35% increases in apoptotic cell death were observed following treatment with 100, 200, and 300 microg STE/ml, respectively, and 51-85% decreases in apoptotic cell death were observed with the antioxidants. The results demonstrate that STE produces oxidative tissue damage and apoptosis, which can be attenuated by antioxidants including vitamin C, vitamin E, a combination of vitamins C plus E and GSPE. GSPE exhibited better protection against STE than vitamins C and E, singly and in combination.

Protective ability of acetylsalicylic acid (aspirin) to scavenge radiation induced free radicals in J774A.1 macrophage cells

Radiation generates a variety of free radicals during the exposure of biological tissues through radiolysis of water. These free radicals are highly reactive and cause oxidative damage to biological molecules. This study examined the protective ability of aspirin against radiation induced oxidative stress. The study assessed the protective effect of aspirin (0.05 mM, 0.10 mM, 0.50 mM) on the generation of free radicals during exposure of J774A.1 macrophage cells to radiation (13.25 cGy). Approximately a 2.2-fold increase in superoxide anion formation as determined by cytochrome c reduction was observed following exposure of the cells to radiation for 20 one second exposures. Preincubation with aspirin exhibited a dose dependent decrease in free radical production as assessed by chemiluminescence and cytochrome c reduction. Aspirin also produced a concentration dependent reduction in radiation induced DNA damage in the cells. The data indicate that radiation of these cells results in production of reactive oxygen species and DNA damage, and aspirin can decrease these effects in a concentration dependent manner.

Induction of oxidative stress and DNA damage by chronic administration of naphthalene to rats

Naphthalene is a bicyclic aromatic compound that is widely used in various domestic and commercial applications including lavatory scent disks, soil fumigants and moth balls. Little information is available regarding the mechanism of naphthalene toxicity. We have assessed the oral, low dose (0.05 LD50) chronic effects of naphthalene (110 mg/kg/day p.o. in corn oil) for 120 consecutive days on lipid peroxidation and DNA fragmentation in the liver and brain tissues of female Sprague-Dawley rats. The animals were sacrificed on 0, 15, 30, 45, 60, 75, 90, 105 and 120 days of treatment. Maximum increases in hepatic and brain lipid peroxidation and DNA fragmentation were observed between 90 and 105 days of treatment. Following administration of naphthalene for 90 days, approximately 1.4- and 1.3-fold increases in lipid peroxidation were observed in the hepatic and brain tissues, respectively, while under the same conditions and time points 1.9- and 2.5-fold increases in hepatic and brain DNA fragmentation were observed, respectively. These results demonstrate that low dose chronic administration of naphthalene induces an oxidative stress resulting in tissue damaging effects that may contribute to the toxicity and carcinogenicity of naphthalene.

Naphthalene-induced oxidative stress and DNA damage in cultured macrophage J774A.1 cells

Naphthalene is a bicyclic aromatic compound that is widely used in various domestic and commercial applications including lavatory scent disks, soil fumigants and moth balls. However, little information is available regarding the mechanism of naphthalene toxicity. We have assessed the concentration-dependent in vitro effects of naphthalene on increased lipid peroxidation, cytochrome c reduction, hydroxyl radical production, modulation of intracellular oxidized states by laser scanning confocal microscopy, and DNA fragmentation in cultured macrophage J774A.1 cells. The cells were incubated with 0-500 microM concentrations of naphthalene for 0, 12 and 24 h at 37 degrees C. Concentration- and time-dependent changes were observed. No significant changes were observed with concentrations of naphthalene up to 100 microM. At 24 h, lipid peroxidation increased by 1.8-, 2.4- and 2.9-fold at 200, 300 and 500 microM concentrations of naphthalene. Approximately 2.0-, 3.1- and 4.6-fold increases in cytochrome c reduction were observed at 200, 300 and 500 microM concentrations of naphthalene, respectively, at this time point demonstrating the production of superoxide anion, while under the same conditions approximately 2.4-, 3.2- and 4.9-fold increases in hydroxyl radical production were observed, respectively. Following incubation of these cells with 200 and 500 microM concentrations of naphthalene 2.3- and 4.7-fold increases in fluorescence intensity were observed, respectively, as compared to the untreated cells. At 24 h, approximately 1.8-, 2.3- and 3.0-fold increases in DNA fragmentation were observed following incubation with 200, 300 and 500 microM concentrations of naphthalene, respectively. Naphthalene also produced concentration- dependent decreases in cell viability. At the 12 h time point, significant changes were observed only with 300 and 500 microM concentrations of naphthalene. These results demonstrate that naphthalene may induce toxic manifestations by enhanced production of oxygen free radicals, resulting in lipid peroxidation and DNA damage.

Subchronic effects of smokeless tobacco extract (STE) on hepatic lipid peroxidation, DNA damage and excretion of urinary metabolites in rats

The oral use of moist smokeless tobacco products (snuff) is causally associated with cancer of the mouth, lip, nasal cavities, esophagus and gut. The mechanism by which smokeless tobacco constituents produce genetic and tissue damage is not known. Recent studies in our laboratories have shown that an aqueous extract of smokeless tobacco (STE) activates macrophages with the resultant production of reactive oxygen species (ROS), including nitric oxide. Furthermore, the administration of acute doses of STE (125-500 mg/kg) to rats induces dose dependent increases in mitochondrial and microsomal lipid peroxidation, enhances DNA single strand breaks, and significantly increases the urinary excretion of the lipid metabolites malondialdehyde, formaldehyde, acetaldehyde and acetone. Since the use of tobacco is a chronic process, the effects of an aqueous extract of STE in rats following low dose exposure were examined. Female Sprague-Dawley rats were treated orally with 25 mg STE/kg every other day for 105 days. The effects of subchronic treatment of STE on hepatic microsomal and mitochondrial lipid peroxidation and the incidence of hepatic nuclear DNA damage were assessed. Lipid peroxidation increased 1.4- to 3.3-fold in hepatic mitochondria and microsome with STE treatment between 0 and 105 days with respect to control animals while hepatic DNA single strand breaks increased up to 3.4-fold. Maximum increases in lipid peroxidation and DNA single strand breaks occurred between 75 and 90 days of treatment. Urinary excretion of the four lipid metabolites malondialdehyde, formaldehyde, acetaldehyde and acetone was monitored by high pressure liquid chromatography (HPLC) with maximum increases being observed between 60 and 75 days of treatment. The results clearly indicate that low dose subchronic administration of STE induces an oxidative stress resulting in tissue damaging effects which may contribute to the toxicity and carcinogenicity of STE.

Stress, diet and alcohol-induced oxidative gastrointestinal mucosal injury in rats and protection by bismuth subsalicylate

Oxygen free radicals are implicated in the pathogenesis of stress and food/alcohol-induced gastrointestinal injury. We have investigated the effects of restraint stress, spicy food diet, high-fat diet and 40% ethanol on the enhanced production of reactive oxygen species, including superoxide anion and hydroxyl radicals, and on DNA fragmentation, lipid peroxidation and membrane microviscosity (indices of oxidative tissue damage) in gastric and intestinal mucosa of Sprague-Dawley rats. Furthermore, the protective ability of bismuth subsalicylate (BSS; 15 mg kg(-1) was determined against the gastrointestinal mucosal injury induced by these stressors. Animals on the high-fat diet consumed 31% more food as compared to other animals. Animals on the spicy food diet consumed ca. 23% more water as compared to control animals, and the high-fat diet animals consumed 17% less water. Restraint stress provided greater injury to both gastric and intestinal mucosa as compared to other stressors. Restraint stress, spicy food diet, high-fat diet and ethanol increased superoxide anion production by 10.0-, 4.3-, 5.7- and 4.8-fold, respectively, in the gastric mucosa, and by 10.4-, 5.3-, 7.0- and 5.5-fold in the intestinal mucosa. Exposure to restraint stress, spicy food diet, high-fat diet and 40% ethanol also increased hydroxyl radical production by ca. 14.3-, 4.5-, 3.5- and 4.8-fold, respectively, in the gastric mucosa, and by 17.0-, 4.8-, 3.5- and 4.7-fold in the intestinal mucosa. Bismuth subsalicylate administration to the animals provided significant protection against superoxide anion and hydroxyl radical production. Restraint stress, spicy food diet, high-fat diet and ethanol increased lipid peroxidation by 3.6-, 2.4-, 2.6- and 2.0-fold, respectively, in the gastric mucosa, and by 4.1-, 3.5-, 3.6- and 2.7-fold in intestinal mucosa. Administration of BSS decreased restraint stress, spicy food diet, high-fat diet and ethanol-induced gastric mucosal lipid peroxidation by ca. 26%, 36%, 45% and 18%, and intestinal mucosa lipid peroxidation by 20%, 21%, 46% and 42%, respectively. Approximately 4.0-, 2.0-, 2.4- and 2.0-fold increases in DNA fragmentation were observed in the gastric mucosa of rats exposed to restraint stress, spicy food diet, high-fat diet and 40% ethanol, respectively, and similar increases in the intestinal mucosa. These same four stressors increased membrane microviscosity by 11.6-, 6.1-, 7.3- and 5.4-fold, respectively, in the gastric mucosa, and by 16.2-, 7.9-, 9.5- and 7.8-fold in the intestinal mucosa. Bismuth subsalicylate exerted significant protection against DNA damage and changes in membrane microviscosity induced by the four stressors. Excellent correlations existed between the production of reactive oxygen species and the tissue damaging effects in both gastric and intestinal mucosa. In summary, the results demonstrate that physical and chemical stressors can induce gastrointestinal oxidative stress and mucosal injury through enhanced production of reactive oxygen species, and that BSS can significantly attenuate gastrointestinal injury by scavenging these reactive oxygen species.

Protective effects of grape seed proanthocyanidins and selected antioxidants against TPA-induced hepatic and brain lipid peroxidation and DNA fragmentation, and peritoneal macrophage activation in mice

1. The comparative protective abilities of a grape seed proanthocyanidin extract (GSPE) (25-100 mg/kg), vitamin C (100 mg/kg), vitamin E succinate (VES) (100 mg/kg) and beta-carotene (50 mg/kg) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced lipid peroxidation and DNA fragmentation in the hepatic and brain tissues, as well as production of reactive oxygen species by peritoneal macrophages, were assessed. 2. Treatment of mice with GSPE (100 mg/kg), vitamin C, VES and beta-carotene decreased TPA-induced production of reactive oxygen species, as evidenced by decreases in the chemiluminescence response in peritoneal macrophages by approximately 70%, 18%, 47% and 16%, respectively, and cytochrome c reduction by approximately 65%, 15%, 37% and 19%, respectively, compared with controls. 3. GSPE, vitamin C, VES and beta-carotene decreased TPA-induced DNA fragmentation by approximately 47%, 10%, 30% and 11%, respectively, in the hepatic tissues, and 50%, 14%, 31% and 11%, respectively, in the brain tissues, at the doses that were used. Similar results were observed with respect to lipid peroxidation in hepatic mitochondria and microsomes and in brain homogenates. 4. GSPE exhibited a dose-dependent inhibition of TPA-induced lipid peroxidation and DNA fragmentation in liver and brain, as well as a dose-dependent inhibition of TPA-induced reactive oxygen species production in peritoneal macrophages. 5. GSPE and other antioxidants provided significant protection against TPA-induced oxidative damage, with GSPE providing better protection than did other antioxidants at the doses that were employed.

Induction of oxidative stress in brain tissues of mice after subchronic exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin

The ability of single doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to induce oxidative stress in hepatic and some extrahepatic tissues of animals is well documented. However, no previous study has examined the ability of TCDD to induce oxidative stress and tissue damage in brain in vivo. In this study the ability of TCDD to induce oxidative stress in brain tissues of mice was studied after subchronic exposures. Groups of female B6C3F1 mice were treated orally with TCDD (0, 0.45, 1.5, 15, and 150 ng/kg/day) for 13 weeks, 5 days/week. The animals were euthanized 3 days after the last treatment and brain tissues were collected. Biomarkers of oxidative stress including production of superoxide anion, lipid peroxidation, and DNA-single-strand breaks (SSB) were determined. TCDD treatment resulted in significant and dose-dependent increases in the production of superoxide anion as assessed by reduction of cytochrome c. Significant increases were also observed in lipid peroxidation and DNA-SSB in those tissues, as assessed by the presence of thiobarbituric acid-reactive substances and the alkaline elution technique, respectively. These results clearly indicate that subchronic exposure to low doses of TCDD can induce oxidative tissue damage in brain tissues which may at least in part play a role in the effects of TCDD on the central nervous system.

Stress, diet and alcohol-induced oxidative gastrointestinal mucosal injury in rats and protection by bismuth subsalicylate

Oxygen free radicals are implicated in the pathogenesis of stress and food/alcohol-induced gastrointestinal injury. We have investigated the effects of restraint stress, spicy food diet, high-fat diet and 40% ethanol on the enhanced production of reactive oxygen species, including superoxide anion and hydroxyl radicals, and on DNA fragmentation, lipid peroxidation and membrane microviscosity (indices of oxidative tissue damage) in gastric and intestinal mucosa of Sprague-Dawley rats. Furthermore, the protective ability of bismuth subsalicylate (BSS; 15 mg kg(-1) was determined against the gastrointestinal mucosal injury induced by these stressors. Animals on the high-fat diet consumed 31% more food as compared to other animals. Animals on the spicy food diet consumed ca. 23% more water as compared to control animals, and the high-fat diet animals consumed 17% less water. Restraint stress provided greater injury to both gastric and intestinal mucosa as compared to other stressors. Restraint stress, spicy food diet, high-fat diet and ethanol increased superoxide anion production by 10.0-, 4.3-, 5.7- and 4.8-fold, respectively, in the gastric mucosa, and by 10.4-, 5.3-, 7.0- and 5.5-fold in the intestinal mucosa. Exposure to restraint stress, spicy food diet, high-fat diet and 40% ethanol also increased hydroxyl radical production by ca. 14.3-, 4.5-, 3.5- and 4.8-fold, respectively, in the gastric mucosa, and by 17.0-, 4.8-, 3.5- and 4.7-fold in the intestinal mucosa. Bismuth subsalicylate administration to the animals provided significant protection against superoxide anion and hydroxyl radical production. Restraint stress, spicy food diet, high-fat diet and ethanol increased lipid peroxidation by 3.6-, 2.4-, 2.6- and 2.0-fold, respectively, in the gastric mucosa, and by 4.1-, 3.5-, 3.6- and 2.7-fold in intestinal mucosa. Administration of BSS decreased restraint stress, spicy food diet, high-fat diet and ethanol-induced gastric mucosal lipid peroxidation by ca. 26%, 36%, 45% and 18%, and intestinal mucosa lipid peroxidation by 20%, 21%, 46% and 42%, respectively. Approximately 4.0-, 2.0-, 2.4- and 2.0-fold increases in DNA fragmentation were observed in the gastric mucosa of rats exposed to restraint stress, spicy food diet, high-fat diet and 40% ethanol, respectively, and similar increases in the intestinal mucosa. These same four stressors increased membrane microviscosity by 11.6-, 6.1-, 7.3- and 5.4-fold, respectively, in the gastric mucosa, and by 16.2-, 7.9-, 9.5- and 7.8-fold in the intestinal mucosa. Bismuth subsalicylate exerted significant protection against DNA damage and changes in membrane microviscosity induced by the four stressors. Excellent correlations existed between the production of reactive oxygen species and the tissue damaging effects in both gastric and intestinal mucosa. In summary, the results demonstrate that physical and chemical stressors can induce gastrointestinal oxidative stress and mucosal injury through enhanced production of reactive oxygen species, and that BSS can significantly attenuate gastrointestinal injury by scavenging these reactive oxygen species.

Protective effects of zinc salts on TPA-induced hepatic and brain lipid peroxidation, glutathione depletion, DNA damage and peritoneal macrophage activation in mice

1. The comparative protective abilities of zinc L-methionine, zinc DL-methionine, zinc sulfate, zinc gluconate, L-methionine, DL-methionine, and vitamin E succinate (VES) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced lipid peroxidation, DNA fragmentation, and glutathione depletion in the hepatic and brain tissues, and production of reactive oxygen species by peritoneal macrophages were assessed. In addition, mice were fed a zinc-deficient diet for 5 weeks, and treated with TPA and/or zinc L-methionine or zinc DL-methionine, and similar studies were conducted. 2. The zinc-deficient diet induced oxidative stress in the hepatic and brain tissues as well as in the peritoneal macrophages as evidenced by significantly enhanced lipid peroxidation. DNA fragmentation, glutathione depletion, and production of reactive oxygen species. 3. Treatment of mice with zinc L-methionine, zinc DL-methionine, and VES decreased TPA-induced reactive oxygen species production as evidenced by significant decreases in chemiluminescence in peritoneal macrophages by approximately 45%, 31%, and 47%, respectively, and cytochrome c reduction by approximately 54%, 35%, and 41%, respectively, as compared with control values. Similar results were observed with liver and brain lipid peroxidation, DNA fragmentation, and glutathione depletion. 4. Zinc salts and antioxidants provided significant protection against TPA-induced oxidative damage. Zinc L-methionine provided the best protection.

Chronic effects of smokeless tobacco extract on rat liver histopathology and production of HSP-90

Tobacco consumption is a worldwide problem. The recent increase in the consumption of the smokeless tobacco products (snuff and chewing tobacco) has stimulated interest into the carcinogenic effects of these forms of tobacco. The use of smokeless tobacco products has increased in popularity as the use of cigarettes has become less socially acceptable. For most individuals the use of tobacco is a chronic process. Therefore, the effects of an aqueous extract of smokeless tobacco (STE) in rats following low-dose exposure were examined. Female Sprague-Dawley rats were treated orally with 25 mg STE/kg every other day for 90 days. In order to obtain information regarding the cytotoxicity of STE, the ultrastructural changes occurring in livers of rats following administration of STE were examined under light and electron microscopy. Electron microscopy revealed that in the perisinusoidal spaces an accumulation of indistinct filamentous material occurred following 60 days of treatment, occupying most of the sinusoids. Moreover, the lipids were in a state of disintegration. Significant increases in 90 kDa protein expression were also observed due to chronic treatment with STE. Western blot analysis using a polyclonal mouse antibody against heat shock/stress protein 90 (HSP90) confirmed that the overexpressed proteins were heat shock/stress proteins (HSPs). The HSPs are believed to serve as adaptive or survival functions involving a rapid but transient reprogramming of cellular metabolic activity to protect cells from oxidative damage.

Modulation of TCDD-induced fetotoxicity and oxidative stress in embryonic and placental tissues of C57BL/6J mice by vitamin E succinate and ellagic acid

The ability of vitamin E succinate and ellagic acid to modulate 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced developmental toxicity and oxidative damage in embryonic/fetal and placental tissues was studied in C57BL/6J mice. Vitamin E succinate (100 mg/kg per day) and ellagic acid(6 mg/kg per day) were administered by gavage to groups of pregnant mice on days 10, 11 and 12 of gestation and 40 mg vitamin E succinate/kg or 3 mg ellagic acid/kg on day 13 of gestation. A number of animals from the vitamin E succinate and ellagic acid treated groups also received 30 microg TCDD/kg on day 12 of gestation, 2 h prior to vitamin E succinate or ellagic acid treatment. Groups of treated animals were terminated on day 14 of gestation, and the biomarkers of oxidative stress, including superoxide anion production and the induction of lipid peroxidation and DNA-single strand breaks (SSB), were determined in whole embryonic and placental tissues homogenates. Groups of treated animals were also killed on day 18 of gestation for investigation of the fetotoxic and teratogenic effects as well as effects on the placentae. Vitamin E succinate and ellagic acid significantly decreased TCDD-induced fetal growth retardation fetal death and placental weight reduction, with no significant ameliorating effects on TCDD-induced malformations including cleft palate and hydronephrosis. Vitamin E succinate treatment resulted in decreases of 77-88%, 70-87%, and 21-47% in the production of superoxide anion, lipid peroxidation and DNA-SSB, respectively, in embryonic and placental tissues, while ellagic acid caused 47-98%, 79-93%, and 37-53% decreases, respectively, in these parameters. These results indicate that TCDD-induced fetal death and fetal and placental weight reductions in C57BL/6J mice may be due to oxidative damage induced by TCDD, and ellagic acid and vitamin E succinate provide protection against those effects. Ellagic acid provided better protection than vitamin E succinate against TCDD-induced fetal growth retardation and increases in lipid peroxidation in embryonic and placental tissues.

Comparative induction of oxidative stress in cultured J774A.1 macrophage cells by chromium picolinate and chromium nicotinate

The concentration-dependent effects of chromium picolinate and chromium nicotinate were assessed on the enhanced production of reactive oxygen species including superoxide anion and hydroxyl radicals, and lipid peroxidation and DNA fragmentation in cultured macrophage J774A.1 cells. The macrophage cells were incubated with 0-50 micrograms/ml [corrected] concentrations of these chromium (III) salts for 0 and 24 hrs at 37 degrees C. Concentration-dependent effects were observed. Lipid peroxidation increased by 1.3-1.5-fold following treatment of these cells with chromium picolinate while at these same concentrations of chromium nicotinate approximately 1.2-1.8-fold increases in lipid peroxidation were observed. Increases of 1.0-1.5-fold occurred in the production of superoxide anion as determined by cytochrome c reduction following treatment with chromium picolinate while with these same concentrations and conditions only 1.1-1.2-fold increases in cytochrome c reduction were observed following treatment with chromium nicotinate. Approximately 1.2-1.5-fold increases in hydroxyl radical production were observed following treatment of these macrophage cells with increasing concentrations of chromium picolinate and chromium nicotinate. Incubation of the cells with 30-50 micrograms/ml concentrations of chromium picolinate produced 1.2-1.6 fold increases in DNA fragmentation, while under these same conditions with chromium nicotinate 1.2-1.3-fold increases in DNA fragmentation occurred. No significant loss in cell viability was observed with either chromium salt. These results demonstrate that incubation of macrophage J774A.1 cells with these chromium salts induces low levels of oxidative stress as demonstrated by the biochemical assay techniques employed in this study.

Protection against chemically-induced oxidative gastrointestinal tissue injury in rats by bismuth salts

Oxygen free radicals (OFR) are implicated in the pathogenesis of stress, chemically induced gastric lesions, and gastrointestinal injury. The concentration-dependent scavenging abilities of bismuth subsalicylate (SBS), colloidal bismuth subcitrate (CBS), and selected OFR scavengers, including superoxide dismutase (SOD), catalase, mannitol, and allopurinol were examined against biochemically or chemically generated superoxide anion, hydroxyl radical, and hypochlorite radical plus hypochlorous acid based on a chemiluminescence assay. Furthermore, both gastric (GM) and intestinal mucosa (IM) were individually exposed in vitro to these free radical generating systems, and the concentration-dependent protective abilities of SBS and CBS against lipid peroxidation (LP) were compared with selected OFR scavengers. In addition, 24-hr fasted rats were orally treated with the necrotizing agents 0.6 M HCl, 0.2 M NaOH, 80% ethanol, and aspirin (200 mg/kg). The extent of tissue injury in the GM and IM was determined by assessing LP, DNA fragmentation, and membrane microviscosity. Dose- and time-dependent in vivo protective abilities of CBS (100 mg/kg) and SBS (15 mg/kg) were also assessed. Following incubations with superoxide anion and hydroxyl radical generating systems in the presence of 125 mg SBS/liter, approximately 47% and 61% inhibitions were observed in the chemiluminescence response, respectively, while 48% and 46% inhibitions were observed with 125 mg CBS/liter. SBS and CBS exerted similar abilities towards hypochlorite radical plus hypochlorous acid. Approx. 3.1- and 3.7-fold increases in LP were observed in the GM and IM of rats following oral administration of 0.6 M HCl. Pretreatment of the rats with SBS and CBS decreased 0.6 M HCl-induced LP in the GM by approx. 39% and 27%, respectively, with similar decreases in LP in the IM. SBS exhibited better protective abilities towards 0.6 M HCl and 0.2 m NaOH-induced GM and IM injury as compared to CBS. SBS and CBS provided similar protection towards 80% ethanol-induced gastric injury, while CBS exerted a superior protective ability towards aspirin-induced gastric injury. The results demonstrate that both SBS and CBS can scavenge reactive oxygen species and prevent tissue damage produced by OFR.

Interrelationship between cellular calcium homeostasis and free radical generation in myocardial reperfusion injury

This review describes the interrelationship between two important biological factors, intracellular calcium overloading and oxygen-derived free radicals, which play a crucial role in the pathogenesis of myocardial ischemic reperfusion injury. Free radicals are generated during the reperfusion of ischemic myocardium, and polyunsaturated fatty acids in the membrane phospholipids are the likely targets of the free radical attack. On the other hand, activation of phospholipases can provoke the breakdown of membrane phospholipids which results in the activation of arachidonate cascade leading to the generation of prostaglandins, and oxygen free radicals can be produced during the interconversion of the prostaglandins. In conclusion, it has been emphasized that the two seemingly different causative factors of reperfusion injury, intracellular calcium overloading and free radical generation are, in fact, highly interrelated.

Comparative in vitro and in vivo protein kinase C activation by selected pesticides and transition metal salts

Various pesticides and transition metals induce oxidative deterioration of biological macromolecules. Protein kinase C (PKC) may mediate these effects. However, no information is available regarding whether these xenobiotics can modulate PKC which is a critical event signaling the increase in endothelial permeability and cell proliferation. Female Sprague-Dawley rats were treated p.o. with two 0.25 LD50 doses of selected pesticides and transition metal salts at 0 and 21 h, and killed at 24 h. PKC activities were measured in liver and brain tissues. Cultured PC-12 cells were incubated for 24 h with 50, 100 or 200 nM concentrations of these pesticides, while 0.20, 0.40 or 0.60 microM concentrations of cadmium chloride (Cd(II)) and sodium dichromate (Cr(VI)) salts were employed. PKC activations were observed in the hepatic and brain cytosol fractions by all xenobiotics. Approximately 1.4- to 2.0-fold and 1.6- to 3.5-fold increases in PKC activity in the hepatic and brain cytosol fractions were observed, respectively. In the hepatic tissues, the greatest increases in activities were observed with TCDD, chlorpyrifos, endrin and Cd(II), while chlorpyrifos and fenthion exerted the greatest increases in the brain tissues. In cultured PC-12 cells, the greatest activation of PKC was observed primarily with 100-nM concentrations of the pesticides. The maximum effects were induced by chlorpyrifos, fenthion, Cd(II) and Cr(VI) salt. The results clearly indicate that pesticides as well as Cd(II) and Cr(VI) salts can modulate a vital component of the cell signaling pathway, namely PKC activity. PKC may be a target of free radicals and oxidative stress, leading to altered cell proliferation and differentiation.

Oxygen free radical scavenging abilities of vitamins C and E, and a grape seed proanthocyanidin extract in vitro

Proanthocyanidins, a group of polyphenolic bioflavonoids, have been reported to exhibit a wide range of biological, pharmacological and chemoprotective properties against oxygen free radicals. We have assessed the concentration-dependent oxygen free radical scavenging abilities of a grape seed proanthocyanidin extract (GSPE), vitamin C and vitamin E succinate (VES) as well as superoxide dismutase, catalase and mannitol against biochemically generated superoxide anion and hydroxyl radical using a chemiluminescence assay and cytochrome c reduction. A concentration-dependent inhibition was demonstrated by GSPE. At a 100 mg/l concentration, GSPE exhibited 78-81% inhibition of superoxide anion and hydroxyl radical. Under similar conditions, vitamin C inhibited these two oxygen free radicals by approximately 12-19%, while VES inhibited the two radicals by 36-44%. The combination of superoxide dismutase and catalase inhibited superoxide anion by approximately 83%, while mannitol resulted in an 87% inhibition of hydroxyl radical. The results demonstrate that GSPE is a more potent scavenger of oxygen free radicals as compared to vitamin C and VES.

Comparative in vitro oxygen radical scavenging ability of zinc methionine and selected zinc salts and antioxidants

1. The concentration-dependent scavenging abilities of zinc DL-methionine, zinc sulfate, zinc gluconate, zinc picolinate and selected free radical scavengers, including superoxide dismutase (SOD), catalase, mannitol, allopurinol and DL-methionine, were examined against biochemically generated superoxide anion, hydroxyl radical and hypochlorite radical plus hypochlorous acid, by chemiluminescence and cytochrome c reduction. 2. Zinc methionine was the most effective of the zinc compounds that were tested. Following incubations with superoxide anion, hydroxyl radical, and hypochlorite radical-generating systems, in the presence of 50 microM zinc DL-methionine approximately 38%, 47% and 28% inhibition in reactive oxygen species generation was observed, respectively, compared to control groups. 3. The protective abilities of various zinc salts, as well as selected free radical scavengers and antioxidants were also assessed on phorbol ester (TPA)-induced lactate dehydrogenase (LDH) release from cultured PC-12 cells. Preincubation showed better protection than coincubation. Approximately 45% and 50% inhibition in TPA-induced LDH leakage was observed following preincubation with 50 microM zinc DL-methionine and 50 microM vitamin E succinate, respectively. Zinc DL-methionine exhibited better protection against LDH leakage than any other zinc salt tested. 4. The results indicate that zinc DL-methionine can attenuate the biochemical consequences of oxygen free radicals, and is comparable to other well-known antioxidants and free radical scavengers in the in vitro system that was employed.

Induction of oxidative stress by chronic administration of sodium dichromate [chromium VI] and cadmium chloride [cadmium II] to rats

Recent studies have demonstrated that both chromium (VI) and cadmium (II) induce an oxidative stress, as determined by increased hepatic lipid peroxidation, hepatic glutathione depletion, hepatic nuclear DNA damage, and excretion of urinary lipid metabolites. However, whether chronic exposure to low levels of Cr(VI) and Cd(II) will produce an oxidative stress is not shown. The effects of oral, low (0.05 LD50) doses of sodium dichromate [Cr(VI); 2.5 mg/kg/d] and cadmium chloride [Cd(II); 4.4 mg/kg/d] in water on hepatic and brain mitochondrial and microsomal lipid peroxidation, excretion of urinary lipid metabolites including malondialdehyde, formaldehyde, acetaldehyde and acetone, and hepatic nuclear DNA-single strand breaks (SSB) were examined in female Sprague-Dawley rats over a period of 120 d. The animals were treated daily using an intragastric feeding needle. Maximum increases in hepatic and brain lipid peroxidation were observed between 60 and 75 d of treatment with both cations. Following Cr(VI) administration for 75 d, maximum increases in the urinary excretion of malondialdehyde, formaldehyde, acetaldehyde, and acetone were 2.1-, 1.8-, 2.1-, and 2.1-fold, respectively, while under the same conditions involving Cd(II) administration approximately 1.8-, 1.5-, 1.9-, and 1.5-fold increases were observed, respectively, as compared to control values. Following administration of Cr(VI) and Cd(II) for 75 d, approximately 2.4- and 3.8-fold increases in hepatic nuclear DNA-SSB were observed, respectively, while approximately 1.3- and 2.0-fold increases in brain nuclear DNA-SSB were observed, respectively. The results clearly indicate that low dose chronic administration of sodium dichromate and cadmium chloride induces an oxidative stress resulting in tissue damaging effects that may contribute to the toxicity and carcinogenicity of these two cations.

TCDD endrin and lindane induced increases in lipid metabolites in maternal sera and amniotic fluids of pregnant C57BL/6J and DBA/2J mice

TCDD, endrin and lindane induce an oxidative stress and enhance lipid peroxidation in fetal and placental tissues of mice. The levels of the products resulting from altered lipid metabolism, including malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) have been determined in maternal sera and amniotic fluids of pregnant C57BL/6J and DBA/2J mice after oral administration of single fetotoxic doses of TCDD, endrin and lindane on day 12 of gestation, using high pressure liquid chromatography (HPLC). Under these conditions, TCDD given at a dose of 30 micrograms/kg body weight to C57BL/6J mice produced 2.5-3.9 and 1.7-4.0 fold increases in the levels of the four metabolites in maternal sera and the amniotic fluids, respectively. TCDD given to DBA/2J mice at a dose of 60 micrograms/kg produced 1.5-1.7 and 1.7-2.2 fold increases in the levels of these metabolites in maternal sera and the amniotic fluids, respectively. Endrin, when given at a dose of 4.5 mg/kg body weight to either mouse strain, produced increases of 1.9-3.1 and 1.7-3.2-fold in the levels of the four metabolites in maternal sera and the amniotic fluids, respectively, in the C57BL/6J mice and increases of 1.4-1.6 and 1.2-1.5 fold in the levels of these metabolites in maternal sera and the amniotic fluids, respectively, in the DBA/2J mice. Lindane given at a dose of 30 mg/kg body weight to C57BL/6J mice produced 1.5-2.0 and 1.3-1.7-fold increases in the four metabolites in maternal serum and amniotic fluids, respectively, while administration of this same dose to DBa/2J mice produced 1.2-1.5 and 1.1-1.5 fold increases, respectively. Increases in the levels of lipid metabolites occur in maternal serum and amniotic fluid as a result of enhanced lipid peroxidation in response to TCDD, endrin and lindane. Lipid peroxidation may participate in the fetotoxic effects of these xenobiotics and these effects are observed regardless of the Ah-responsiveness of the mice, although higher levels of the metabolites are produced by TCDD in Ah-responsive mice.

Cadmium-induced production of superoxide anion and nitric oxide, DNA single strand breaks and lactate dehydrogenase leakage in J774A.1 cell cultures

The involvement of reactive oxygen species in the toxicity of cadmium (Cd) has been proposed. We have, therefore, examined the effects of this cation on the production of superoxide anion and nitric oxide and DNA single strand breaks in J774A.1 macrophage cells in culture as well as the effects on lactate dehydrogenase (LDH) leakage and cell viability. Following a 48-h incubation, over 2-fold increases in superoxide anion and nitric oxide (NO) production were observed at a Cd concentration of approximately 0.60 microM, while a 50% decrease in viability was observed at this concentration. LDH leakage paralleled the superoxide anion and nitric oxide production. Concentration-dependent increases in DNA single strand breaks (SSB) were observed after incubation with Cd with a maximum increase occurring at a concentration of approximately 0.40 microM. The results indicate that Cd is toxic to the J774A.1 cell line, and support the hypothesis that the toxicity may be due at least in part to an oxidative stress induced by the production of reactive oxygen species following exposure to this cation.