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

Nutrient reference values for Australia and New Zealand: Including recommended dietary intakes

In aerobic organisms, oxygen is essential for efficient energy production but paradoxically, produces chronic toxic stress in cells. Diverse protective systems must exist to enable adaptation to oxidative environments. Oxidative stress (OS) results when production of reactive oxidative species (ROS) exceeds the capacity of cellular antioxidant defenses to remove these toxic species. Epidemiological and clinical studies have linked environmental factors such as diet and lifestyle to cancer, diabetes, atherosclerosis, and neurodegenerative disorders. All of these conditions, as well as the aging process, are associated with OS due to elevation of ROS or insufficient ROS detoxification. Many environmental pollutants engage signaling pathways that are activated in response to OS. The same sequences of events are also associated with the etiology and early pathology of many chronic diseases. Investigations of oxidative responses in different in vivo models suggest that, in complex organisms such as mammals, organs and tissues contain distinct antioxidant systems, and this may form the basis for differential susceptibility to environmental toxic agents Thus, understanding the pathways leading to the induction of antioxidant responses will enable development of strategies to protect against oxidative damage. We shall review evidence of organ-specific antioxidant responses elicited by environmental pollutants in humans and animal models.

The role of antioxidants and antioxidant-related enzymes in protective responses to environmentally induced oxidative stress

Cytotoxicity and oxidative mechanisms of different forms of chromium.

Mitochondrial proton F0F1-ATPase/ATP synthase synthesizes ATP during oxidative phosphorylation. In this study, we examined the effects of several groups of polyphenolic phytochemicals on the activity of the enzyme. Resveratrol, a stilbene phytoalexin that is present in grapes and red wine, concentration-dependently inhibited the enzymatic activity of both rat brain and liver F0F1-ATPase/ATP synthase (IC(50) of 12 - 28 microM). Screening of other polyphenolic phytochemicals using rat brain F0F1-ATPase activity resulted in the following ranking potency (IC(50) in parenthesis): piceatannol (8 microM)>resveratrol (19 microM)=(-)epigallocatechin gallate (17 microM)>(-)epicatechin gallate, curcumin (45 microM)>genistein=biochanin A=quercetin=kaempferol=morin (55 - 65 microM)>phloretin=apigenin=daidzein (approx. 100 microM). Genistin, quercitrin, phloridzin, (+)catechin, (+)epicatechin, (-)epicatechin and (-)epigallocatechin had little effect at similar concentrations. Tannic acid, theaflavins (tea extract) and grape seed proanthocyanidin extract (GSPE) had IC(50) values of 5, 20 and 30 microg ml(-1), respectively. Several monophenolic antioxidants and non-phenolic compounds were ineffective at concentrations of 210 microM or higher. The inhibition of F0F1-ATPase by resveratrol and genistein was non-competitive in nature. The effects of polyphenolic phytochemicals were additive. Both resveratrol and genistein had little effect on the Na(+)/K(+)-ATPase activity of porcine cerebral cortex, whereas quercetin had similar inhibitory potency as for F0F1-ATPase. In conclusion, the ATP synthase is a target for dietary phytochemicals. This pharmacological property of these phytochemicals should be included in the examination of their health benefits as well as potential cytotoxicity.

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Inhibition of mitochondrial proton F0F1-ATPase/ATP synthase by polyphenolic phytochemicals

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.

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

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

Helicobacter pylori has been identified in the pathogenesis of chronic active gastritis and peptic ulcer disease and is epidemiologically linked to gastric cancer and lymphoma. Our previous studies have demonstrated enhanced production of reactive oxygen species (ROS) in cultured gastric adenocarcinoma cells (ATCC CRL/1739) in association with H. pylori. Recently, we have isolated and cultured normal human gastric mucosal cells (GMC) from H. pylori-negative endoscopic biopsies. The integrity of these mucosal cells was determined by periodic acid-Schiff staining. We assessed the effects of various H. pylori strains including 60190 (a 87-kDa cytotoxin producing strain), ATCC 43504, and 60190-v1 (in which the cytotoxin gene has been disrupted) on the primary culture of human gastric mucosal cells. The induction of ROS and DNA fragmentation in the mucosal cells in association with these H. pylori strains were assessed by cytochrome c reduction (an index of superoxide anion production), hydroxyl radical production, and DNA fragmentation. Following incubation of the mucosal cells with 1:0.5 and 1:1 ratios of H. pylori strain 60190, approximately 6.2- and 9.9-fold increases were observed in cytochrome c reduction, respectively, as compared to mucosal cells in the absence of H. pylori, demonstrating the production of superoxide anion. The detection of hydroxyl radicals based on the formation of 2,3-dihydroxybenzoic acid and 2,5-dihydroxybenzoic acid was determined by using a high-performance liquid chromatograph equipped with an electrochemical detector. Approximately 3.5- and 7.7-fold increases in hydroxyl radical production were observed following incubation of the mucosal cells with 1:0.5 and 1:1 ratios of H. pylori, respectively. Approximately 3.6- and 4.5-fold increases in DNA fragmentation were observed in gastric mucosal cells following incubation with 1:0.5 and 1:1 ratios of H. pylori, respectively. The effects of culture supernatant preparations from H. pylori strains 60190 and 60190-v1 on the enhanced production of ROS and increased DNA fragmentation in mucosal cells were also investigated. Culture supernatant preparations, the prime source of the 87-kDa cytotoxin, from both H. pylori strains 60190 and 60190-v1 were extracted under identical conditions to determine the role of 87-kDa cytotoxin on the enhanced production of ROS and DNA fragmentation. The cytotoxin rich-H. pylori strain 60190 induced greater production of ROS and DNA fragmentation in mucosal cells as compared to the supernatant preparation from H. pylori strain 60190-v1, in which the cytotoxin gene has been disrupted. This study demonstrates that H. pylori induces enhanced production of ROS and DNA damage in association with human gastric mucosal cells and that the 87-kDa cytotoxin protein plays a prime role in the induction of oxidative stress and DNA damage.

Helicobacter pylori-induced oxidative stress and DNA damage in a primary culture of human gastric mucosal cells.

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.

X. Ye

Papers

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

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

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

Helicobacter pylori-induced oxidative stress and DNA damage in a primary culture of human gastric mucosal cells.

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