Source: UNIVERSITY OF KENTUCKY submitted to NRP
ANTIOXIDANT NUTRIENTS, REACTIVE OXYGEN SPECIES AND OXIDATIVE STRESS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
0205006
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Jun 7, 2005
Project End Date
Jun 6, 2010
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
UNIVERSITY OF KENTUCKY
500 S LIMESTONE 109 KINKEAD HALL
LEXINGTON,KY 40526-0001
Performing Department
HUMAN ENVIRONMENTAL SCIENCES
Non Technical Summary
Antioxidant inadequacy and environmental agents cause oxidative stress, which contribute to the pathogenesis of many degenerative diseases. This project examines if antioxidant nutrients,individually or in combination, protect against oxidative damage resulting from environmental stress.
Animal Health Component
(N/A)
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
7023999101070%
7233999101030%
Knowledge Area
702 - Requirements and Function of Nutrients and Other Food Components; 723 - Hazards to Human Health and Safety;

Subject Of Investigation
3999 - Animal research, general;

Field Of Science
1010 - Nutrition and metabolism;
Goals / Objectives
The long-term goal of the proposed research is to determine the influence of dietary and environmental factors on nutrient requirements so that the optimal requirement can be established. The hypothesis that antioxidant nutrients mediate the generation of reactive oxygen species (ROS), which in turn modulate cellular susceptibility to environmental stress, will be tested. Mitochondrion is the major producer of superoxide, which plays a central role in the formation of other reactive oxygen species (ROS). Available evidence suggests that dietary vitamin E, alone or in combination with other antioxidant nutrients, may down-regulate ROS generation, and that ROS may promote the release iron from its protein complex. Free iron has potential to initiate oxidative tissue damage. Additionally, ROS may mediate the activation and/or expression of redox-sensitive biological modifiers, which in turn mediate vital cellular events and thereby alter cellular susceptibility to environmental stress. Specifically, the proposed research seeks to determine 1)if dietary vitamin E, individually or in combination with selenium, alpha-lipoic acid and/or beta-carotene, mediate ROS generation and iron release, 2)if dietary vitamin E, individually or in combination with selenium, alpha-lipoic acid and/or beta-carotene modulate redox-sensitive biological modifiers, and 3)if dietary vitamin E, individually or in combination with selenium, alpha-lipoic acid and/or beta-carotene, attenuate the adverse effects of iron-overload and nitrite treatment.
Project Methods
The proposed research seeks to test the hypothesis that antioxidant nutrients mediate the levels and generation of reactive oxygen species, which in turn modulate events that are vital to cellular susceptibility to environmental stress. Specifically, if dietary vitamin E, individually or in combination with alpha-lipoic acid and/or beta-carotene, mediate ROS generation and iron release, modulate the activation/expression of biological modifiers, and attenuate the adverse effects resulting from iron-overload or nitrite treatment using rodents as experimental animals. Following the quarantine period, two to four-month-old male/female Sprague-Dawley rats or B6C3 mice will be randomly divided and fed one of the synthetic diets. The basal diet, similar to the AIN 93M purified diet that contains 20 IU vitamin E (as RRR alpha-tocopherol) and 0.05 mg selenium (as sodium selenite)/kg diet (no beta-carotene or R-alpha-lipoic acid) will be supplemented with either 0, 100 or 500 IU vitamin E, 0 or 500 mg R-alpha-lipoic acid, 0 or 500 mg beta-carotene, and 0 or 0.5 mg Se (as sodium selenite) per kg diet. For studying the effect of environmental stress, additional animals from each dietary group will be fed the same diet supplemented with either 1000 mg nitrite (as sodium nitrite) or 1000 mg iron (as ferric citrate) per kg diet. Control groups will receive equivalent sodium chloride and potassium citrate, respectively. Diets will be prepared weekly and stored frozen pending use. Water and feed will be provided to experimental animals ad libitum. During the experimental period, animals will be monitored for weighed weekly and their health status examined periodically. Based on information available, feed intake is not expected to vary significantly during the experimental period. Should significant discrepancies occur, the lowest amount consumed by a giving group will be fed to other groups during the next feeding day. Animal mortality, which is not expected to occur, if any, will be recorded and the cause of the death determined by pathologists. At the end of 1, 2 or 5 months on the respective diets, 6-8 animals from each group will be killed by intraperitoneous injection of sodium pentobarbital. Portions of liver and skeletal muscle will be removed, blotted, weighed and processed for biochemical measurements or histopathological examinations.

Progress 06/07/05 to 06/06/10

Outputs
OUTPUTS: Nitrites, important antimicrobial and flavoring/coloring agents widely-used in meat products, may cause fatal methemoglobinemia and other adversary effects. However, the mechanism by which nitrite exerts its adversary effect is not yet clear. Sprague-Dawley rats fed a nutrient adequate diet are rather resistant to the adversary effect of 2000 ppm sodium nitrite in drinking water. However, when nitrite-treated rats were fed a vitamin E-deficient and low selenium diet, over 40% were dead or moribund in nine weeks, while no mortality resulted from those supplemented with either vitamin E or selenium. All nitrite-treated rats fed the vitamin E-deficient and low selenium diet developed massive liver necrosis, mild to markedly muscular degeneration, tubular nephrosis and eosinophilic enteritis. No pathological lesions were observed in nitrite-treated rats supplemented with either selenium or vitamin E. Studies have shown that nitrites are both oxidation product and precursor of nitric oxide (NO.), which may react with superoxide to form highly reactive peroxynitrite (ONOO-). Also, vitamin E may mediate the generation and availability of superoxide, and seleno-proteins may reduce ONOO-. Results obtained have been reported in the professional meeting and in the process of being published PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Findings suggest that increased formation of ONOO- in nitrite-treated rats receiving low vitamin E and selenium may lead to tissue lesions and subsequent mortality, and that vitamin E and selenium may protect against the adverse effects of nitrites by reducing reactive ONOO-. Information obtained from the study supports the hypothesis that nutritional status of affected subjects may alter their cellular susceptibility to environmental agents.

Publications

  • Chow, C.K. Association of fruit and vegetables consumption and colorectal cancer risk: a role of cigarette smoking. Am. J. Clin. Nutr. 91: 238-238, 2010.
  • Chow, C.K. Dietary fat intake and subsequent weight change in adults. Am. J. Clin. Nutr. 92: 463-464, 2010.
  • Chow, C.K. Dietary intake of menaquinones and risk of cancer incidence and mortality. Am. J. Clin. Nutr. 92: 1533-1534, 2010.
  • Chow, C.K. and C.B. Hong. Effect of dietary vitamin E and selenium on nitrite toxicity. Proc. 3rd Int. Conf. Sci. Tech., Penang, in press, 2010.


Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: Manganese superoxide dismutase (Mn-SOD), which catalyzes the dismutation of superoxide to hydrogen peroxide, is an important antioxidant enzyme in aerobic organisms. Labile iron or free iron associated with low molecule mass has the potential to participate in redox cycling and catalyze the formation of hydroxyl radical from superoxide/hydrogen peroxide. The state and levels of labile iron or available form of iron can be modified by oxidants or reductants acting on cell iron sources. Information obtained from in vitro and cell culture studies suggests that several compounds, including superoxide and hydrogen peroxide, may release iron from such protein complexes as mitochondrial iron-sulfur clusters, transferrin and ferritin. Previous studies have shown that increased expression of Mn-SOD did not alter the status of other antioxidant systems, but it attenuates oxidative damage to membrane lipids. To further determine the role of Mn-SOD gene in cellular antioxidant defense, liver and skeletal muscle of 16 week old male transgenic Mn-SOD mice and their non-transgenic litter mates were analyzed for the rates of mitochondrial hydrogen peroxide generation and the levels of labile iron. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
The results showed that the liver and skeletal muscle of transgenic Mn-SOD mice had significantly lower rates of both mitochondrial hydrogen peroxide generation and the levels of labile iron than and their non-transgenic litter mates. The findings suggest that reduced rate of mitochondrial hydrogen peroxide generation may attenuate iron release from its protein complex, and support the view that the conditions that favor superoxide/hydrogen peroxide generation may also lead to an increased iron release, and initiation of oxidative damage.

Publications

  • Chow, C.K. (2009)Role of vitamin E in cellular antioxidant defense. Current Chemical Biology 3: 197-202. Chow, C.K. (2009)Fatty acid composition of plasma phospholipids and risk of prostate cancer. Am. J. Clin. Nutr. 89: 1946-1946. Chow, C.K. (2009) Dietary β-tocopherol and serum levels of sex hormone-binding globulin. J. Nutr. 139: 2007-2007.


Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: Manganese superoxide dismutase (Mn-SOD), which catalyzes the dismutation of superoxide, is an important antioxidant enzyme in aerobic organisms. To determine the role of Mn-SOD in cellular antioxidant defense, the oxidative and antioxidative status in the tissues of 16 week-old male transgenic mice that express increased level of Mn-SOD. Immediately after the mice were killed, heart, brain, kidney, lung, liver and skeletal muscle were processed to determine the degree of oxidative stress, and antioxidant status. The levels of lipid peroxidation products, thiobarbituric acid reactants, were significantly lower the in the heart, liver, skeletal muscle, and kidney, but not in brain and lung, of Mn-SOD transgenic mice than their nontransgenic littermates. The levels of conjugated dienes and protein carbonyls were not significantly different between transgenic mice and their nontransgenic littermates in any organs examined. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
The levels of GSH and vitamin E, and the activities of catalase, Cu-Zn-SOD, Se-GSH peroxidase, and non-Se-GSH peroxidase were not significantly different between transgenic mice and their nontransgenic littermates in any organs examined. The data suggest that alteration of Mn-SOD expression does not alter the status of other antioxidant systems, and that increased express of Mn-SOD may attenuates oxidative damage to membrane lipids.

Publications

  • Lobb, K. and C.K. Chow. Fatty acid classification and nomenclature. In Fatty Acids in Foods and Their Health Implications (C.K. Chow, ed.), 3rd ed., pp.1-15, CRC Press, Boca Raton, FL, 2008.
  • Chang, S.J. and C.K. Chow. Fatty acids in fermented food products. In Fatty Acids in Foods and Their Health Implications (C.K. Chow, ed.), 3rd ed., pp. 317-334, CRC Press, Boca Raton, FL, 2008.
  • Tatum, V. and C.K. Chow. Effects of processing and storage on fatty acids in edible oils. In Fatty Acids in Foods and Their Health Implications (C.K. Chow, ed.), 3rd ed., pp. 493-510. CRC Press, Boca Raton, FL, 2008.
  • Chang, S.J. and C.K. Chow. Consumption of fatty acids. In Fatty Acids in Foods and Their Health Implications (C.K. Chow, ed.), 3rd ed., pp. 545-559. CRC Press, Boca Raton, FL, 2008.
  • Chow, C.K. Biological effects of oxidized fatty acids. In Fatty Acids in Foods and Their Health Implications (C.K. Chow, ed.), 3rd ed., pp. 855-878, CRC Press, Boca Raton, FL, 2008.
  • Chow, C.K. The relative efficacy of lycopene and β-carotene in inhibiting experimental metastasis of human hepatoma SK-Hep1 cells in athymic nude mice. J. Nutr. 138: 2289-2289, 2008.
  • Chow, C.K. Plasma tocopherols and risk of cognitive impairment. Am. J. Clin. Nutr. 88: 1447-1448, 2008.
  • Chow, C.K. Consumption of cured meats and risk of chronic obstructive pulmonary disease. Am. J, Clin. Nutr. 88:1703-1703, 2008.
  • Ibrahim W.H., C.K. Chow, H. M. Habib, and G. G. Bruckner Soy isoflavones reduce oxidative damage in mice liver. Int. J. Vitamins Nutr. Res., in press, 2008.
  • Ibrahim, W., V.L. Tatum, C.C. Yeh, C.B. Hong and C.K. Chow. Effect of dietary carnosine on oxidative stress and antioxidant status of rats. Int. J. Vitamins Nutr. Res., in press, 2008.
  • Chow, C.K. Current status and future prospect of health foods. Proc. 2nd Int. Conf. Sci. Tech., in press, 2008.
  • Chow, C.K. Role of vitamin E in cellular antioxidant defense. Current Chemical Biology, in press, 2008.
  • Chow, C.K. Editor, Fatty Acids in Foods and Their Health Implications (C.K. Chow, ed.), 3rd ed., pp. 1-1281, CRC Press, Boca Raton, FL, 2008.


Progress 01/01/07 to 12/31/07

Outputs
OUTPUTS: Vitamin E is the major lipid-soluble chain-breaking antioxidant that prevents free radical-initiated peroxidative tissue damage, and plays a central role in the overall antioxidant defense. The antioxidant property of vitamin E is attributable to its more rapid reaction with peroxy radicals several orders of magnitude faster than with acyl lipids. The free radical scavenging reaction of vitamin E reduces the available superoxide and related reactive oxygen/nitrogen species. However, the mechanism by which vitamin E exerts its protective effect against oxidative tissue damage has yet to be delineated. Previous studies have shown that dietary vitamin E reduced generation and/or levels of superoxide. As superoxide has potential to release iron from its transport and storage proteins, labile or available form of iron is capable of catalyzing the formation of reactive hydroxyl radicals, in order to understand how vitamin E exerts its antioxidant function, the effect of dietary vitamin E on labile iron pool was studied in rats. One-month-old Sprague-Dawley male and female rats were fed a basal vitamin E-deficient diet supplemented with 0, 20, 200, or 2,000 iu vitamin E/kg diet for 90 days. The levels of labile iron were measured in the liver, kidney, spleen, heart and skeletal muscle. Additionally, the levels of lipid peroxidation products were measured. The results showed that, except for labile iron in the heart of male rats, dietary vitamin E dose-dependently reduced the levels of labile iron and lipid peroxidation products in all tissues of male and female rats. Superoxide and/or hydrogen peroxide has potential to release labile or available form of iron from its protein complexes. Since labile or available form of iron is capable of catalyzing the formation of hydroxyl radicals as well as the decomposition of lipid hydroperoxides to form more free radicals, an increase in labile iron is expected to cause an increase in the levels of oxidation products. The findings suggest that vitamin E may exert its antioxidant function by attenuating iron release by reducing available superoxide. These data also supports the notion that labile or available form of iron plays an important role in initiating peroxidative damage to membrane lipids and important cellular components. PARTICIPANTS: Chow, C.K.

Impacts
Protection against free radical-initiated oxidative damage has long been accepted as the most important biological function proposed for vitamin E. However, the mechanism by which vitamin E exerts its antioxidant function at the tissue level has yet to be delineated. The findings that dietary vitamin E attenuates the levels of labile or reduced iron, which is capable of catalyzing the formation of reactive hydroxyl radicals from superoxide and hydrogen peroxide, provide a rational explanation as to how vitamin E may exerts its antioxidant function at the tissue level.

Publications

  • Chow, C.K. Role of vitamin E in cellular antioxidant defense - a new perspective. In new topics in vitamin E research (o.h. Bellock, ed.), nova science publishers, hauppauge, ny, pp. 99-110, 2007.
  • Chow, C.K. Grape powder polyphenols and atherosclerosis development. J. Nutr. 136: 2272-2272, 2006.
  • Chow, C.K. And w. Ibrahim. Dietary vitamin E, but not coenzyme q10, reduces labile iron levels in rat tissues. Metal ions biol. Med. 9: 346-351, 2006.
  • Chow, C.K. Does potassium-enriched salt or sodium reduction reduce cardiovascular mortality and medical expenses? Am. J. Clin. Nutr. 84: 1552-1553, 2006.
  • Chow, C.K. and S.J. Chang. Value or usefulness of the food frequency questionnaire for the assessment of dietary total antioxidant capacity. J. Nutr. 137: 1496-1497, 2007.
  • L.W. Robertson, I.G. Berberian, T. Borges, l.-C. Chen, C.K. Chow, H.P. Glauert, J. Filser and H. Thomas. Suppression of peroxisomal enzyme activities and cytochrome p4504a isozyme expression by congeneric polybrominated and polychlorinated biphenyls. Ppar res., vol. 2007, article id 15481, 5 pages, 2007.