DNA damage, a biomarker of carcinogenesis: its measurement and modulation by diet and environment

Free radicals and other reactive oxygen or nitrogen species are constantly generated in vivo and can cause oxidative damage to DNA. This damage has been implicated to be important in many diseases, including cancer. The assessment of damage in various biological matrices, such as tissues, cells, and urine, is vital to understanding this role and subsequently devising intervention strategies. During the last 20 years, many analytical techniques have been developed to monitor oxidative DNA base damage. High-performance liquid chromatography-electrochemical detection and gas chromatography-mass spectrometry are the two pioneering contributions to the field. Currently, the arsenal of methods available include the promising high-performance liquid chromatography-tandem mass spectrometry technique, capillary electrophoresis, 32P-postlabeling, antibody-base immunoassays, and assays involving the use of DNA repair glycosylases such as the comet assay. The objective of this review is to discuss the biological significance of oxidative DNA damage, evaluate the effectiveness of several techniques for measurement of oxidative DNA damage in various biological samples and review current research on factors (dietary and non-dietary) that influence DNA oxidative damage using these techniques.     

Effect of high-voltage electrostatic field pretreatment on the antioxidant system in stored green mature tomatoes

BACKGROUND: High‐voltage electrostatic field (HVEF), as a feasible and non‐chemical technique, applied to food preservation is a new area of study. Our previous research suggested HVEF could maintain the quality of tomato in storage. The present article intensively investigated the effect of HVEF pretreatment on antioxidant system of green mature tomato in storage. RESULTS: Green mature tomatoes were exposed to negative (or positive) HVEF for 2 h at 20 °C and then stored for 24 days at 13 ± 1 °C, 85–90% relative humidity. The results indicated HVEF significantly reduced contents of O₂^? and H₂O₂ of tomato fruits during storage compared to the control. HVEF treatment also enhanced the activities of antioxidant enzymes including catalase, superoxide dismutase, ascorbate peroxidase and peroxidase. The contents of non‐enzyme antioxidant components including reduced glutathione, phenols and ascorbic acid also were increased by HVEF treatment. However, HVEF treatment did not increase the content of lycopene in tomato fruit. CONCLUSION: HVEF treatment could promote the antioxidant capacity of tomato fruits in storage. Further research is be highly recommended to understand the mechanisms improving the antioxidant capacity of tomato fruits by HVEF. Copyright © 2011 Society of Chemical Industry     

Lipopolysaccharide derived from the digestive tract provokes oxidative stress in the liver of dairy cows fed a high-grain diet

The aims of this study were to measure oxidative stress parameters and to investigate the molecular mechanism triggered by grain-induced subacute ruminal acidosis in mid-lactation cows. Twelve Holstein-Friesian cows with an average weight of 455 ± 28 kg were divided into 2 groups and subjected to 2 diets over 18 wk: either a low-grain (forage-to-concentrate ratio = 6:4) or a high-grain (forage-to-concentrate ratio = 4:6) diet based on dry matter. Being fed a long-term high-grain diet resulted in a significant decrease in rumen pH and a significant increase in ruminal lipopolysaccharide (LPS) at 4 h postfeeding in the morning. The increase was also observed in LPS concentrations in the portal vein, hepatic vein, and jugular vein blood plasma as well as reduced milk yield in a high-grain diet. Cows fed a high-grain diet had lower levels of catalase and glutathione peroxidase (GPx) activity and total antioxidant capacity than cows fed a low-grain diet; however, super oxide dismutase (SOD) activity and malondialdehyde (MDA) levels were higher in both the liver and the plasma of high-grain than in low-grain cows. Positive correlations were observed between plasma LPS versus hepatic MDA, plasma MDA, and hepatic SOD activity, whereas hepatic GPx and plasma GPx were negatively correlated with plasma LPS. The relative mRNA abundances of GPX1 and CAT were significantly lower in the liver of cows fed a high-grain diet than those fed a low-grain diet, whereas SOD1 was significantly higher in cows fed a high-grain diet than cows fed a low-grain diet. The expression levels of Nrf2, NQO1, MT1E, UGT1A1, MGST3, and MT1A were downregulated, whereas NF-kB was upregulated, in cows fed a high-grain diet. Furthermore, nuclear factor E2-related factor 2 (Nrf2) total protein and mRNA levels were significantly lower than in low-grains. Our results demonstrate the relationship between the translocated LPS and the suppression of cellular antioxidant defense capacity, which lead to increased oxidative stress and suggests that the Nrf2-dependent antioxidant response may be affected by higher levels of LPS translocated to the bloodstream.     

Effect of hesperidin and naringin on the plasma lipid profile and plasma antioxidant activity in rats fed a cholesterol‐containing diet

The objective of this study was to compare the influence of hesperidin and naringin, the main flavonones of orange and grapefruit, on plasma lipid profile and antioxidant activity in rats fed a cholesterol‐containing diet. Sixty male Wistar rats were randomly divided into six groups of 10, named Control, Hesperidin, Naringin, Chol, Chol/Hesperidin and Chol/Naringin. The Control group was fed a basal diet (BD) and 1–2 mL of distilled water. To the BD of the other five groups were added 0.1–0.2 mg of hesperidin dissolved in 1–2 mL of distilled water (Hesperidin group), 0.46–0.92 mg of naringin in 1–2 mL of water (Naringin group), 1% of non‐oxidised cholesterol (NOC) and 1–2 mL of water (Chol), 1% of NOC and 0.1–0.2 mg of hesperidin in 1–2 mL of water (Chol/Hesperidin), 1% of NOC and 0.46–0.92 mg of naringin in 1–2 mL of water (Chol/Naringin). After 30 days of the experiment it was found that the diets supplemented with hesperidin and naringin increased the plasma antioxidant activity. In conclusion, diets supplemented with hesperidin and naringin significantly hindered the increase in plasma lipid levels caused by cholesterol feeding. Hesperidin and naringin, bioactive compounds of citrus fruits, are powerful plasma lipid lowering and plasma antioxidant activity increasing flavonones. Copyright © 2007 Society of Chemical Industry     

Comparative in vivo antioxidant capacity of DL-2-hydroxy-4-methylthiobutanoic acid (HMTBA) and DL-methionine in male mice fed a high-fat diet

BACKGROUND: In animal diets, methionine (Met) is considered to be the first limiting amino acid, and the activity of synthetic Met is typically added either as DL ‐methionine (DLM) or as DL ‐2‐hydroxy‐4‐methylthiobutanoic acid (HMTBA). It has been demonstrated that HMTBA exhibits a higher antioxidant capability in vitro as compared to DLM. However, the difference in antioxidant capability between DLM and HMTBA in vivo is unknown. METHODS: In the present study, 60 male C57BL/6 mice were randomly divided into six groups and fed either a normal diet (NFD, 5.37% fat) or a high‐fat diet (HFD, 19.7% fat) in conjunction with 0.2% DLM, 0.2% HMTBA or 0.1% DLM and 0.1% HMTBA for 4 weeks. RESULTS: HFD supplemented with 2% DLM and NFD with 2% HMTBA both induced adverse affects in relation to serum lipid parameters and depressed antioxidant defense systems in the digestive system. However, these changes were restored in the 0.2% HMTBA‐treated HFD group. Furthermore, no significant differences were found in the lipid parameters and antioxidant status in the NFD and HFD group supplemented with 0.1% DLM and 0.1% HMTBA. CONCLUSION: HMTBA restored oxidative redox status under OS conditions and its antioxidant properties were positively correlated with the dosage included in diet. Copyright © 2011 Society of Chemical Industry     

Structural and antioxidant modification of wheat peptides modified by the heat and lipid peroxidation product malondialdehyde

Wheat peptides, the biological active peptides derived from foods, has an array of biological actions, including antiobesity, antimicrobial, and angiotensin I-converting enzyme inhibitory effects in mammalian species. Recent studies showed that some wheat peptides may show the noteworthy antioxidant potency against the peroxidation of lipids or fatty acids, but the effect of oxidation on its antioxidant activities is unclear. In the present study, we demonstrate that heat and malandialdehyde (MDA)-oxidized wheat peptides lose its surface hydrophobicity and reducing power, and show a relatively lower free radical-scavenging activitiy in vitro. Those modifications also lead to gradual formation of aggregates in wheat peptides and induce more reactive oxygen species (ROS) production in vivo. These findings indicate that oxidation may influence the functional properties and directly alter the structure of wheat peptides, and lead to the loss of its antioxidant potency both in vitro and in vivo, thereby providing a novel explanation for some of the potential health risks proposed for oxidized food in human.     

膳食蛋白、机体抗氧化调节与健康的关系研究进展

膳食蛋白为机体提供必需氨基酸,还具有广泛的生理功能。膳食蛋白的消化代谢过程中,机体细胞会产生活性氧。活性氧积累可能引发氧化及衰老。细胞中的抗氧化蛋白——硫氧还蛋白、谷氧还蛋白及其他抗氧化酶等共同组成抗氧化系统,抵御活性氧,减少有害物生成。本文综合介绍不同来源的膳食蛋白与相应的抗氧化调节对机体健康的影响,以及活性氧代谢过程中两种抗氧化蛋白的调控作用,结合体内其他抗氧化指标,从而更好地认识不同膳食蛋白的代谢差异,指导个人膳食与健康。      

Improving effect of a probiotic mixture on memory and learning abilities in d-galactose–treated aging mice

The aim of this study was to evaluate the antiaging effect of a probiotic mixture using an in vivo mouse model in which aging was induced with d-galactose. Results of the Morris water maze test indicated that long-term administration of the probiotic mixture improved memory and learning abilities and ameliorated the apoptosis pattern in the hippocampus of aging mice treated with d-galactose. An antioxidation experiment indicated that administration of the probiotic mixture could restore activities of the antioxidant enzymes superoxide dismutase and catalase and inhibit the production of malondialdehyde. The antioxidant-related proteins nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) were upregulated in liver after treatment of d-galactose–treated aging mice with probiotics. Finally, the probiotic treatment did affect the production of short-chain fatty acids in d-galactose–treated aging mice. Our results highlighted a possible antioxidative effect triggered by short-chain fatty acids that contributed to improving the memory and learning abilities following treatment with the probiotic mixture and suggested that probiotics could serve as a therapy to modulate physiological function.     

Effects of highly purified sardine proteins on lipid peroxidation and reverse cholesterol transport in rats fed a cholesterol-rich diet

The effect of highly purified sardine proteins was compared with that of casein on serum and lipoproteins lipid peroxidation and reverse cholesterol transport. Lecithin:cholesterol acyltransferase (LCAT) activity, high density lipoproteins (HDL₂ and HDL₃) composition and serum lipid and lipoproteins peroxidation were determined in rats fed a cholesterol-rich diet. Hypercholesterolemic rats were divided into two groups fed diets enriched with cholesterol and containing 20% of highly purified sardine proteins (SPc) or casein (CASc) for 28 days. A control group was fed a standard diet (CAS). Compared with CAS and CASc, the thiobarbituric acid reactive substances (TBARS) concentrations of low density lipoprotein (LDL)–HDL₁ in SPc were 3.5- and 1.7-fold higher compared with casein diets. TBARS in HDL₂ and HDL₃ were, respectively, 2.3- and 1.6-fold lower in SPc compared with CASc. In SPc group, LCAT activity was higher compared to CASc and CAS (P < 0.05). Purified sardine proteins had no beneficial effects on LDL-cholesterol and lipid peroxidation. However, they reduced HDL oxidation and improved reverse cholesterol transport, in the hypercholesterolemic rat.     

Incremental amounts of rumen-protected histidine increase plasma and muscle histidine concentrations and milk protein yield in dairy cows fed a metabolizable protein-deficient diet

The dairy industry can benefit from low crude protein (CP) diets due to reduced N excretion, but shortages of Met, Lys, and His may limit milk protein synthesis. We studied the effect of incremental amounts of rumen-protected (RP)-His on plasma and muscle AA profile, nutrient utilization, and yields of milk and milk true protein in dairy cows. Eight multiparous Holstein cows (130 ± 30 d in milk) were randomly assigned to treatment sequences in a replicated 4 × 4 Latin square design with 28-d experimental periods. Treatments included a basal diet composed (dry matter basis) of 50% corn silage, 15% haylage, and 35% concentrate supplemented with 0, 82, 164, and 246 g/d of RP-His and 11 g/d of RP-Met. Milk, plasma, and muscle samples were collected weekly or every other week during all 4 periods, whereas spot urine and fecal grab samples were taken only in wk 4 of each period. Data were analyzed individually by week using linear, quadratic, and cubic orthogonal polynomials and repeated measures. Plasma His increased linearly with RP-His during wk 1 (30.3 to 57.2 µM) to wk 4 (33.2 to 63.1 µM). Plasma carnosine increased linearly with supplemental RP-His except in wk 2. No treatment effect was observed for plasma 3-methylhistidine except a quadratic effect in wk 3. Inclusion of RP-His showed linear effects on muscle His in wk 2 (20.1 to 32.5 µM) and 4 (20.3 to 35.5 µM). Whereas muscle anserine and carnosine concentrations were not affected by treatments in wk 4, anserine responded quadratically and carnosine showed a trend for a quadratic response to RP-His in wk 2. During wk 4, treatments did not affect urinary excretion of total purine derivatives, as well as dry matter intake and milk concentrations of fat and true protein. In contrast, milk yield tended to increase linearly (31.2 to 32.7 kg/d) and milk true protein yield responded linearly (0.93 to 0.98 kg/d) and tended to increase quadratically to RP-His supplementation in wk 4. Also, milk urea-N (11.7 to 12.9 mg/dL) and urinary excretion of urea-N (23.7 to 27.0% of N intake) increased linearly with feeding RP-His in wk 4. Overall, RP-His was effective to enhance plasma and muscle concentrations of His and milk protein synthesis. Elevated milk urea-N and urinary excretion of urea-N suggest that plasma His may have exceeded the requirement with excess N converted to urea in the liver. Future research is needed to determine the bioavailability of RP-His supplements to improve the accuracy of diet formulation for AA.     

The etiology of oxidative stress in the various species of animals,a review

Oxidative stress is the consequence of an imbalance of pro‐oxidants and antioxidants leading to cell damage and tissue injury. The exhaustion of antioxidant systems is one of the reasons for the occurrence of oxidative stress, which results in avalanche production of reactive oxygen species (ROS) or free radicals. High oxidative stress is common in organs and tissues with high metabolic and energy demands, including skeletal and heart muscle, liver and blood cells. Stress arises in animals in response to unavoidable or adverse environmental conditions. In the external environment, which affects the body of the cow, there are four main groups of stressors: physical, chemical, biological and psychological. Physical stressors include fluctuations in ambient temperature as well as mechanical injuries. High ambient temperature is one of the factors affecting the productivity of cows. Biological stressors are conditioned by errors and irregularities in habits. Both of these phenomena have an adverse impact on both the resistance of animals and fertility and are the etiological agent of oxidative stress. Various mechanisms may be responsible for metal‐induced oxidative stress: direct or indirect generation of ROS, depletion of glutathione and inhibition of antioxidant enzymes are well known for all redox‐active and redox‐inactive metals. © 2014 Society of Chemical Industry