Jaya Balmoori

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.

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 μM concentrations of the two cations for 0, 24, or 48 hours at 37°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 μM, 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 μM 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 μM 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 μM 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.

Comparative effects of TCDD, endrin, naphthalene and chromium (VI) on oxidative stress and tissue damage in the liver and brain tissues of mice

The mechanism of toxicity of structurally diverse environmental toxicants including heavy metals and polyhalogenated and polycyclic hydrocarbons may involve a common cascade of events which entails an oxidative stress and production of reactive oxygen species. We have determined the comparative effects of single 0.01, 0.10 and 0.50 LD(50) doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene and sodium dichromate (chromium VI) on lipid peroxidation, DNA fragmentation and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of C57BL/6NTac mice. The effects of a single acute oral 0.50 LD(50) dose of these xenobiotics on hepatic and brain lipid peroxidation were investigated at 0, 12, 24, 48, and 96 h after treatment, while the effects of 0.10 LD(50) and 0.01 LD(50) doses of these xenobiotics were at 0, 24, 48, 72, and 96 h after treatment. Dose- and time-dependent effects were observed with all four xenobiotics. At a 0.50 LD(50) dose of TCDD, endrin, naphthalene and chromium VI, maximum increases in cytochrome c reduction (superoxide anion production) of approximately 5.7-, 5.4-, 5.3- and 4.1-fold, respectively, were observed in hepatic tissues. TCDD showed an increasing effect through 96 h. Endrin and naphthalene demonstrated a maximum effect at 12-24 h, while chromium VI exhibited a maximum effect at 48 h. With respect to lipid peroxidation, at a 0.50 LD(50) dose both endrin and chromium VI induced the maximum effect at 48 h of treatment, while naphthalene demonstrated the maximum effect after 24 h of treatment. TCDD demonstrated a continued effect through 96 h of treatment. At a 0.50 LD(50) dose TCDD, endrin, naphthalene and chromium VI produced maximum increases in hepatic lipid peroxidation of approximately 3.5-, 3.1-, 3.7- and 3.3-fold in hepatic tissues, respectively. Similar results were obtained in hepatic and brain DNA fragmentation at 0.50 LD(50) doses. Lesser effects were observed with 0.10 and 0.01 LD(50) doses of these xenobiotics as compared to the 0.50 LD(50) dose. The results clearly demonstrate that these diverse xenobiotics induce dose- and time-dependent oxidative stress and tissue damage in the liver and brain tissues of mice.

ACUTE AND CHRONIC STRESS-INDUCED OXIDATIVE GASTROINTESTINAL INJURY IN RATS, AND THE PROTECTIVE ABILITY OF A NOVEL GRAPE SEED PROANTHOCYANIDIN EXTRACT

Reactive oxygen species (ROS) are implicated in the pathogenesis of stress-induced gastrointestinal injury. In the present study, we have investigated the effects of acute stress and chronic stress on the enhanced production of superoxide anion as determined by cytochrome c reduction assay, and correlated the enhanced production of superoxide anion with increased lipid peroxidation, DNA fragmentation and membrane microviscosity, indices of oxidative tissue injury, in gastric mucosa and intestinal mucosa, and determined the protective effects of a novel IH636 grape seed proanthocyanidin extract (GSPE) against mucosal injury. Acute stress was induced by water-immersion restraint stress for 90 min, while chronic stress was induced by water-immersion restraint stress for 15 min/day for 15 consecutive days. Half of the animals exposed to acute stress were pretreated orally with 100 mg GSPE/kg/day for 15 consecutive days. Similarly, half of the animals exposed to chronic stress were pretreated orally with 100 mg GSPE/kg/day for 15 consecutive days. Acute stress produced maximal injury to both gastric mucosa and intestinal mucosa as compared to chronic stress. Acute stress and chronic stress increased cytochrome c reduction by 12.2- and 4.8-fold, respectively, in the gastric mucosa, and 12.1- and 4.6-fold in the intestinal mucosa. Acute stress increased lipid peroxidation, DNA fragmentation and membrane microviscosity by 3.3-, 4.1- and 11.6-fold, respectively, in the gastric mucosa, and 4.4-, 5.2- and 16.6-fold, respectively, in intestinal mucosa. GSPE decreased acute stress-induced lipid peroxidation, DNA fragmentation and membrane microviscosity by 15%, 12% and 13%, respectively, in the gastric mucosa, and by 13%, 14% and 16%, respectively, in the intestinal mucosa. Chronic stress increased lipid peroxidation, DNA fragmentation and membrane microviscosity by 2.9-, 3.3- and 6.3- fold, respectively, in the gastric mucosa, and 3.3-, 4.2- and 9.3-fold, respectively, in the intestinal mucosa. GSPE decreased chronic stress-induced lipid peroxidation, DNA fragmentation and membrane microviscosity by 23%, 21% and 25%, respectively, in the gastric mucosa, and by 26%, 26% and 25%, respectively, in the intestinal mucosa. These results demonstrate that acute stress and chronic stress can induce gastrointestinal oxidative stress and mucosal injury through enhanced production of ROS, and that GSPE provides significant protection against gastrointestinal oxidative stress and mucosal injury by scavenging these ROS.

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.

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.

Role of reactive oxygen species in the development of cytotoxicity with various forms of chewing tobacco and pan masala

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. Use of chewing tobacco is extremely popular in Far East and Middle East countries. In some of these countries, these chewing tobaccos are mixed with areca nut, lime and catechu and sold as pan masala. In this study, we examined three different forms of commercially available pan masala, and examined the development of cytotoxicity using primary culture of normal human oral keratinocytes (NHOKs). NHOK cells were treated with three different forms of pan masala, gutkha, pan masala with saccharin and pan masala as well as Kentucky smokeless chewing tobacco (STE) and the development of oxidative stress, and DNA damage were monitored. The results of our study demonstrated significant amount of the superoxide anion production, lipid peroxidation, DNA fragmentation and DNA ladders with all of the chewing tobacco materials tested. Laser scanning microscopy revealed concentration-dependent effects of STE on the modulation of intracellular redox states. The results, thus, document that the cytotoxic effects of the chewing tobaccos including pan masalas are mediated through the production of the reactive oxygen species.

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 β-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 μg/ml) for 24h 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 μg/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.

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.

Hydrogen peroxide‐induced modulation of intracellular oxidized states in cultured macrophage J774A.1 and neuroactive PC‐12 cells, and protection by a novel grape seed proanthocyanidin extract

We have previously compared selected antioxidants including vitamins C and E, β‐carotene and a novel IH636 grape seed proanthocyanidin extract (GSPE) with respect to their scavenging abilities against biochemically generated free radicals in both in vitro and in vivo models. The results demonstrated that GSPE is a significantly more potent oxygen free radical scavenger compared with vitamins C and E and β‐carotene. GSPE has been reported to exhibit a wide range of biological and pharmacological activities including free radical scavenging, antibacterial, antiviral, antiinflammatory, antiallergic and vasodilator actions.