The antioxidant effect of a diet rich in Maillard reaction products is attenuated after consumption by healthy male adolescents. In vitro and in vivo comparative study

BACKGROUND: Maillard reaction products (MRPs) are widely consumed as a part of the human diet. A 2 week randomised two‐period crossover trial to determine whether MRP intake affects the antioxidant defence system in male adolescents (11–14 years, n = 18) was carried out using two diets rich and poor in MRPs (brown diet, BD, and white diet, WD, respectively). Fasting blood samples were collected after the dietary intervention periods to measure oxidative status. The in vitro antioxidant activity of the diets was also assessed. RESULTS: The BD had stronger in vitro antioxidant activity to scavenge free radicals and greater ability to reduce lipid peroxidation. However, in the in vivo assay, markers of oxidative damage (serum thiobarbituric acid‐reactive substances and erythrocyte hydroperoxides) and antioxidant defence parameters (serum antioxidants and enzymatic activities of catalase, superoxide dismutase and glutathione peroxidase) were unchanged after the dietary treatments. Only treatment of biological samples with external oxidants revealed higher values of the antioxidant capacity after consumption of the MRP‐rich diet. CONCLUSION: In spite of the higher antioxidant activity of the BD shown in vitro, consumption of diets rich in MRPs does not seem to modify oxidative status in healthy male adolescents. However, a protective effect against induced oxidation was shown. Copyright © 2008 Society of Chemical Industry     

Effects of vitamin E supplementation on and the association of body condition score with changes in peroxidative biomarkers and antioxidants around calving in dairy heifers

The objective of this study was to investigate the effect of vitamin E supplementation on oxidative status in blood, liver, milk, and ovarian follicular fluid in periparturient heifers. Vitamin E supplementation started 8 wk before calving and continued until 8 wk postpartum. Grass silage was the main forage fed during the experiment. In addition, supplemented heifers (n = 9) received 3,000 IU of vitamin E daily on a carrier food; control heifers (n = 9) consumed only the carrier food. Blood samples and liver biopsies were taken frequently throughout the study and ovarian follicular fluid was sampled at 8 wk postpartum. Body condition score was scored weekly and milk yield was measured daily. A marker of oxidative damage, determinable reactive oxygen metabolites (d-ROM), and a set of antioxidants were measured in blood, liver, milk, and ovarian follicular fluid. Control heifers had a low vitamin E status, and selenium status was marginal in control and supplemented heifers. Vitamin E supplementation increased vitamin E concentrations in blood, liver, and ovarian follicular fluid and increased triacylglycerol in liver. Serum d-ROM were not reduced by vitamin E supplementation. Superoxide dismutase and glutathione peroxidase activity in red blood cells and liver and glutathione peroxidase activity in ovarian follicular fluid were not affected by vitamin E supplementation and they were not increased around calving. Protein thiol groups and ratio of reduced glutathione to oxidized glutathione were also not increased around calving. These results suggest that heifers around calving experience a low level of oxidative processes. This might be caused by lower than expected milk production attributed to a low forage intake. Serum d-ROM were negatively correlated with protein thiol groups and positively correlated with the activity of glutathione peroxidase in red blood cells, oxidized glutathione, and the ratio of reduced glutathione and oxidized glutathione in serum. The lack of treatment effects allowed estimation of the effects of body condition 4 wk before calving and the loss of body condition on markers of lipid peroxidation and antioxidants. A trend that a body condition of ≥3 might result in more oxidative damage measured by serum d-ROM was observed, but fatter heifers had a significantly higher ratio of reduced glutathione to oxidized glutathione.     

Aqueous extract of Hibiscus sabdariffa L. decelerates acetaminophen‐induced acute liver damage by reducing cell death and oxidative stress in mouse experimental models

BACKGROUND: Acetaminophen (AAP)‐induced oxidative stress can cause cell death to induce liver damage. The antioxidant effect of Hibiscus sabdariffa L. (HS) was shown in previous studies. In this study the effect of HS extract (HSE) on AAP‐induced liver injury in BALB/c mice was investigated. RESULTS: In vivo, BALB/c mice were fed orally with 200, 400 or 600 mg kg⁻¹ HSE for 2 weeks and then injected with 1000 mg kg⁻¹ AAP. Pretreatment with HSE decreased lipid peroxidation and increased catalase activity and glutathione level. It also decreased AAP‐induced liver injury, accompanied by decreased expression of pJNK, Bax and tBid in the liver. Additionally, HSE protected BALB/c normal liver cells from AAP‐induced damage in vitro. CONCLUSION: It has been demonstrated that HSE can protect the mouse liver from AAP‐induced injury and that the protective mechanism might involve decreasing oxidative stress and reducing cell death. Copyright © 2009 Society of Chemical Industry     

Hepatoprotective effect of the root extract of Decalepis hamiltonii against carbon tetrachloride-induced oxidative stress in rats

Decalepis hamiltonii, a climbing shrub, grows in the forests of peninsular India and is consumed for its health promoting properties. The hepatoprotective activity of the aqueous extract of the roots of D. hamiltonii with known antioxidant constituents was studied against carbon tetrachloride (CCl₄)-induced oxidative stress and liver injury in rats. Pretreatment of rats with aqueous extract of the roots of D. hamiltonii, single (50, 100 and 200 mg/kg b.w.) and multiple doses (50 and 100 mg/kg b.w. for 7 days) significantly prevented the CCl₄ (1 ml/kg b.w.) induced hepatic damage as indicated by the serum marker enzymes (AST, ALT, ALP, and LDH). Parallel to these changes, the root extract also prevented CCl₄-induced oxidative stress in the rat liver by inhibiting lipid peroxidation and protein carbonylation, and restoring the levels of antioxidant enzymes (SOD, CAT, GPx, GR, and GST) and glutathione. The biochemical changes were consistent with histopathological observations suggesting marked hepatoprotective effect of the root extract in a dose dependent manner. Protective effect of the aqueous extract of the roots of D. hamiltonii against CCl₄-induced acute hepatotoxicity could be attributed to the antioxidant constituents.     

Antioxidative effects of whey protein on peroxide-induced cytotoxicity

Myoblastic toxicity is a major adverse effect caused by reactive oxygen species (ROS) when exercising heavily. Although protection or alleviation of ROS toxicity can be achieved by administration of antioxidant vitamins such as vitamin E and vitamin C, their protective effect remains controversial. Thus, alternative natural antioxidants may be potential candidates for foods for athletes. In this research, we investigated the antioxidative effect of whey protein against hydrogen peroxide (H₂O₂) toxicity using C₂C₁₂ myoblasts. Whey protein pre-incubation prevented the decrease in cell viability after H₂O₂ treatment. The production of 8-hydroxydeoxyguanosine associated with DNA oxidative damage was also inhibited by the whey protein pre-incubation. Endogenous antioxidant defense, such as glutathione, catalase, and superoxide dismutase activity, was also modulated by the antioxidant. At the same time, enhanced mRNA expression levels of heme oxygenase-1 and NADPH quinone oxidoreductase-1 were observed in cells pre-incubated with whey protein before H₂O₂ abuse. These findings suggest that whey protein improved the antioxidant capacity against acute oxidative stress through multiple pathways and this protein may serve as an alternative source of antioxidants for prevention of athletic injuries caused by ROS.     

Effects of Graptopetalumparaguayense extract on tert‐ butylhydroperoxide‐induced oxidative stress

BACKGROUND: Graptopetalum paraguayense E. Walther is used in folk medicine to lower blood pressure, protect liver function and relieve pain and infection. The effect and mechanism of its 50% ethanolic extract (GE50) were investigated in tert‐butylhydroperoxide (t‐BHP)‐induced Wistar rats. The serum was analysed for aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities while the tissue cytosols were analysed for lipid peroxidation, antioxidant level and enzyme activities. RESULTS: The liver was the primary target organ while the heart appeared to be the least responsive organ for t‐BHP treatment among the three tissues investigated. t‐BHP treatment increased serum AST and ALT activities, which are indicators of liver toxicity, while GE50 pretreatment reduced t‐BHP‐induced liver damage. t‐BHP treatment induced lipid peroxidation in the liver and brain but not in the heart. GE50 pretreatment prevented t‐BHP‐induced lipid peroxidation by maintaining superoxide dismutase (SOD) activity as well as glutathione (GSH) and vitamin C levels in the liver and vitamin E level in the brain. Although t‐BHP treatment did not induce lipid peroxidation in the heart, it caused a decrease in antioxidant level. GE50 pretreatment prevented the t‐BHP‐induced decrease in vitamin C level in the heart. CONCLUSION: GE50 pretreatment in rats protects the liver and brain from possible damage by t‐BHP‐induced lipid peroxidation. Copyright © 2007 Society of Chemical Industry     

Free radicals and antioxidants in food and in vivo: What they do and how they work

A wide variety of oxygen free radicals and other reactive oxygen species can be formed in the human body and in food systems. Transition metal ions accelerate free‐radical damage. Antioxidant defenses, both enzymic and nonenzymic, protect the body against oxidative damage, but they are not 100% efficient, and so free‐radical damage must be constantly repaired. Nonenzymatic antioxidants are frequently added to foods to prevent lipid peroxidation. Several lipid antioxidants can exert prooxidant effects toward other molecules under certain circumstances, and so antioxidants for food and therapeutic use must be characterized carefully. Methods of measuring oxidative damage and trapping free radicals in vivo are briefly discussed. Such methods are essential in checking proposals that increased intake of food‐derived antioxidants (such as antioxidant vitamins) would be beneficial to humans.     

Prevention of cataracts by nutritional and metabolic antioxidants

Among aging disabilities, the one associated with the progressive decline of vision is functionally most disadvantageous. Cataracts are one of the more common causes of such visual disability. Several predisposing factors have been identified in the genesis of this disease. While it is perhaps a multifactorial process, significant developments have taken place in recent years suggesting that oxygen radicals are involved in the development of this aging manifestation. Antioxidant enzymes, such as catalase and superoxide dismutase, have been demonstrated to protect the lens cell membrane from oxidative stress as reflected by the prevention of the Na⁺‐K⁺‐ATPase‐dependent pump deterioration due to oxyradical‐dependent oxidation of its proteins and lipids. From the nutritional point of view, antioxidants such as ascorbate and vitamin E also offer significant protection to the lens against damage due to oxidative stress. Evidence regarding the protective effect of these nutrients has been based on lens organ culture studies in the presence of active oxygen, generated photochemically as well as enzymatically. The experiment involving photochemical environs simulate the status of the eye during the photopic vision. In vivo, the effectiveness of ascorbate against cataracts has been tested in rat pups developing cataracts under the oxidative influence of sodium selenite. Certain antioxidants produced metabolically also may be useful in protecting against cataracts. Pyruvate produced in glucose metabolism seems to be an important antioxidant The efficacy of this compound has been tested within in vitro organ culture as well as in vivo, the latter experiments being done with selenite‐treated rats. There is a hope that these and other nutritional and metabolic antioxidants may one day be useful in delaying or even preventing cataract formation in human beings.     

In vitro study of lipid peroxidation and free radical scavenging activity of cow urine

This study represents a comprehensive analysis and scientific validation of our ancient knowledge about the ethnopharmacological aspects of cow urine by measuring the lipid peroxidation, radical scavenging, and level of reduced glutathione and catalase activity. Graded doses of cow urine were administered orally to experimentally treated rats. Results of liver and plasma from experimentally treated rats indicated that cow urine reduced the levels of thiobarbituric acid reactive substance significantly in all the treatments (P < 0.01). In vitro experiments with the liver of control and experimentally treated rats were also carried out against cumene hydroperoxide-induced lipid peroxidation. On LCMS analysis, the antioxidant component of cow urine was identified as uric acid (m/z 169.07). The results demonstrate that the cow urine-mediated induction of antioxidant level controls oxidative damage, even after minimal processing, and thus is indicative of its potential as a viable substitute of synthetic antioxidants.     

Effect of polyphenolic compounds from Coriandrum sativum on H2O2-induced oxidative stress in human lymphocytes

Polyphenolic compounds are widely distributed in plants and known to be excellent antioxidants in vitro. They have the capacity to reduce free-radical formation by scavenging free radicals and protecting antioxidant defences. The present study evaluated the antioxidant potencies of polyphenolic compounds from a spice, Coriandrum sativum against hydrogen peroxide-induced oxidative damage in human lymphocytes. Pretreatment with polyphenolic rich fractions protected human lymphocytes against H₂O₂-induced oxidative damage. H₂O₂ treatment significantly decreased the activities of antioxidant enzymes, such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase and caused decreased glutathione content and increased thiobarbituric acid-reacting substances (TBARS). Treatment with polyphenolic fractions (50 μg/ml) increased the activities of antioxidant enzymes and glutathione content and reduced the levels of TBARS significantly. Observed reduction in the level of lipid peroxides showed a decreased tendency of peroxidative damage. We conclude that, under these experimental conditions, polyphenolic compounds effectively suppress hydrogen peroxide-induced oxidative stress.     

Evaluation of in vivo antioxidant activities of Ganoderma lucidum polysaccharides in STZ-diabetic rats

Effect of Ganoderma lucidum polysaccharides treatment on blood glucose, serum insulin level, lipid peroxidation, nonenzymic and enzymic antioxidants in the plasma and liver of streptozotocin (STZ)-induced diabetic rats was studied. Adult male rats of Wistar strain, weighing 195 to 250 g, were randomized into control and experimental groups. Experiment group rats were induced diabetes by administration of STZ (45 mg/kg b.wt.) intraperitoneally. The diabetic rats were treated with G. lucidum polysaccharides (60, 120, 180 mg/kg b.wt.) dissolved in 15% dimethyl sulphoxide (DMSO) for 30 days. The normal control rats were treated with 15% DMSO for 30 days. Streptozotocin treatment elevated the levels of lipid peroxidation markers (thiobarbituric acid reactive substances, lipid hydroperoxides and conjugated dienes), and reduced nonenzymic antioxidants (vitamin C and reduced glutathione, vitamin E) levels, and enzymic antioxidants (superoxide dismutase, catalase and glutathione peroxidase) activities in the plasma and liver of untreated diabetic control rats. Decreased level of serum insulin and increased level of blood glucose (BG) were observed in the plasma of untreated diabetic control rats. G. lucidum polysaccharides treatment significantly and dose-dependently increased nonenzymic and enzymic antioxidants, serum insulin level and reduced lipid peroxidation, blood glucose levels in STZ-diabetic rats. From the present study, it can be concluded that G. lucidum polysaccharides can be considered as a potent antioxidant.     

Antioxidant activities of chicken liver hydrolysates by pepsin treatment

This study was divided into two parts: (i) an optimal hydrolysing procedure of chicken liver hydrolysates (CLHs) and (ii) the in vivo antioxidant properties of CLHs via a D‐galactose‐induced mouse model. A pepsin‐to‐raw chicken liver mass ratio (1:400, w:w) and 2‐h hydrolysing period were chosen to manufacture CLHs based on yield, peptide level and antioxidant effect. Molecular masses of CLHs were lower than 10 kDa. CLH was rich in aspartic acid and glutamic acid, and also contained both manganese and selenium, which are essential cofactors of superoxide dismutase and glutathione peroxidase, respectively. The contents of cadmium, mercury, tin, and arsenic in CLHs were very low and even no detectible. Regarding the in vivo antioxidant activity of CLHs, a dosage of 1.2 g D‐galactose kg^?1 body weight increased (P < 0.05) 2‐thiobarbituric acid reactive substances values and decreased (P < 0.05) glutathione and Trolox equivalent antioxidant capacity values, as well as superoxide dismutase, catalase, and glutathione peroxidase activities in serum and organs of mice. However, the in vivo antioxidant capacities were improved (P < 0.05) by supplementing CLHs.     

Correlation of In Vivo and In Vitro Assay Results for Assessment of Free Radical Scavenging Activity of Green Tea Nutraceuticals

Green tea (GT)‐derived catechins; epigallocatechin gallate (EGCG) in particular are commonly used nutraceuticals for their free‐radical scavenging activity (FRSA). The influence of photodegradation on the protective power of GT nutracenticals against oxidative stress was thoroughly explored. Photodegradation of GT extracts was carried out and monitored using orthogonal stability‐indicating testing protocol; in vitro and in vivo assays. Total polyphenol content (TPC) and FRSA were determined spectrophotometrically while EGCG was selectively monitored using SPE‐HPLC. In vivo assessment of photodegraded samples was investigated via measuring a number of biomarkers for hepatic oxidative stress and apoptosis (caspase‐3, inducible nitric oxide synthase, nitric oxide, mitogen‐activated protein kinase, glutathione, thiobarbituric acid reactive substances, nuclear factor kappa beta, and nuclear factor erythroid 2‐related factor) as well as liver damage (alanine transaminase and aspartate transaminase) in serum of rats previously subjected to oxidative stress. Results showed complete degradation of EGCG in photodegraded green tea samples with no correlation with either TPC or FRSA. On the other hand, in vivo assay results revealed not only loss of activity but formation of harmful pro‐oxidants. Photostability was found crucial for the protective effect of GT extract against lead acetate insult. Results confirmed that careful design of quality control protocols requires correlation of chemical assays to bioassays to verify efficacy, stability, and most importantly safety of nutraceuticals.     

Alleviation of plasma,erythrocyte and liver lipidemic-oxidative stress by thymoquinone and limonene in atherogenic suspension fed rats

In the present study, the antioxidant efficacies of thymoquinone (TQ) and limonene (LMN), two main constituents of Nigella sativa seeds, were investigated in relation to plasma, erythrocyte and liver oxidative abnormalities in hyperlipidemic Wistar albino rats. Pretreatment with 10 mg TQ or 200 mg LMN in atherogenic suspension fed rats, effectively reduced the plasma lipid peroxidation markers, conjugated diene, lipid hydroperoxide, malondialdehyde, and replenished the plasma antioxidant capacity by increasing its ferric reducing ability and 2,2-azinobis-3-ethylbenzothiazoline-6-sulfonic acid quenching to near normal levels and modulating the levels of reduced glutathione, enzymatic antioxidants superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione-S-transferase, and erythrocyte membrane-linked ATPases to normalcy. These results demonstrate that radical scavenging/antiperoxidative efficacies of TQ were greater than LMN. Thus, these compounds, especially TQ, play an important and useful role in the preservation of plasma antioxidant status, cellular membrane structure and function of tissues, and may be used as chemopreventative food additives in the prooxidant state related disorders.     

Effects of Graptopetalum paraguayense consumption on serum lipid profiles and antioxidative status in hypercholesteremic subjects

BACKGROUND: Oxidative stress is known to be an important component of cellular damage regarding hypercholesterolemia and its complications. In vitro study had demonstrated that extracts of Graptopetalum paraguayense E. Walther exhibited strong antioxidative activities. This study was aimed at investigating the effect of G. paraguayense consumption on antioxidative status and serum lipid profiles in hypercholesterolemic subjects. RESULTS: Eighteen hypercholesterolemic subjects were instructed to consume 100 g G. paraguayense as a serving of vegetable daily for 8 consecutive weeks. After consumption, there were no changes in waist measurement, body mass index, body fat component, blood pressure, hepatic function (serum alanine aminotransferase activity), renal function (serum creatinine, uric acid) or fasting plasma glucose levels. Daily G. paraguayense consumption significantly increased ascorbic acid and α‐tocopherol levels and decreased malondialdehyde level in plasma. Furthermore, daily G. paraguayense consumption significantly increased glutathione levels, glutathione peroxidase and catalase activities in erythrocyte. However, there were no significant changes in serum total cholesterol, triglyceride, low‐density lipoprotein cholesterol or high‐density lipoprotein cholesterol after G. paraguayense consumption. CONCLUSION: The present study demonstrated that consumption of G. paraguayense may increase in vivo antioxidant activities and have some protective effects in decreasing oxidative stress in hypercholesterolemic subjects. Copyright © 2011 Society of Chemical Industry     

水飞蓟油的体外抗氧化活性及对氧化损伤小鼠的保护作用

目的：研究水飞蓟油的体外抗氧化活性及其对D-半乳糖氧化损伤小鼠的保护作用。方法：通过测定水飞蓟 油对二苯基苦味酰基苯肼自由基、羟自由基的清除能力及其总抗氧化力,研究其体外抗氧化活性;通过测定水飞蓟 油对氧化损伤小鼠血清抗氧化酶活力以及其对小鼠肝组织形态的影响,研究其对氧化损伤小鼠的保护作用。结果： 水飞蓟油具有一定的体外抗氧化能力,并与其质量浓度呈一定的正相关关系;水飞蓟油可显著提高小鼠血清中超氧 化物歧化酶和谷胱甘肽过氧化物酶的活力及总抗氧化能力,可以保护小鼠肝细胞形态的完整性。结论：水飞蓟油具 有一定的体外抗氧化活性,对D-半乳糖氧化损伤小鼠具有明显的保护作用。     

Alcohol metabolizing and antioxidant activities of complex herbal extracts from medicinal plants

The objective of this study was to evaluate the alcohol-metabolizing and antioxidative activities of complex herbal extract (CHE). The alcohol-metabolizing activity of CHE was evaluated by assessing alcohol dehydrogenase (ADH) activity, acetaldehyde dehydrogenase (ALDH) activity, and protective effect against alcohol induced damage in in vitro and in vivo models. In this study, CHE treatment significantly increased ADH and ALDH activities and reduced cell death in alcohol-induced liver cell damage. Moreover, it also significantly reduced the serum alcohol and acetaldehyde concentrations in alcoholfed rats. To define the effect of CHE on alcohol metabolism, its antioxidative activities were estimated by measuring radical scavenging activity, ferric-reducing antioxidant potential ability, and thiobarbituric acid reactive substance, and the results demonstrated a higher antioxidative capacity of CHE than the vitamin C control at a high dose (10 mg/mL). Therefore, this study suggests that CHE can be a potential natural resource for the management of ethanol-induced liver toxicity.     

Ameliorative effect of α‐tocopherol on monosodium glutamate‐induced cardiac histological alterations and oxidative stress

BACKGROUND: Chronic oral intake of high doses of monosodium glutamate (MSG) causes oxidative stress. Oxidative stress plays an important role in the development of cardiac dysfunction and injury. Supplementation with α‐tocopherol protects the body against oxidative stress and its related complications. This study was proposed to examine the protective effect of α‐tocopherol against MSG‐induced biochemical and histological alterations in blood and cardiac tissue of rats for a period of 180 days. RESULTS: Chronic oral administration of MSG (4 g kg^?1) caused oxidative stress that was manifested by significant increase (P < 0.05) in malondialdehyde, conjugated dienes and by the decrease in the activities of superoxide dismutase, catalase, reduced glutathione, glutathione peroxidase and glutathione S‐transferase in cardiac tissue. The significantly increased (P < 0.05) activities of aspartate transaminase, creatine phosphokinase and lactate dehydrogenase in serum suggested a cardiac functional disorder. Moreover, heart muscle fibers showed cloudy swelling, fiber separation and vascular congestion. Administration of α‐tocopherol (200 mg kg^?1) significantly (P < 0.05) attenuated the MSG‐induced biochemical alterations in serum and cardiac tissue. α‐Tocopherol also prevented the pathological changes in cardiac tissue when compared with the MSG‐treated group. CONCLUSION: Our findings suggest that α‐tocopherol may have a protective effect against MSG‐induced cardiotoxicity, possibly through its antioxidant activity. Copyright © 2012 Society of Chemical Industry     

Comparison of the effects of black and green tea on in vitro lipoprotein oxidation in human serum

Lipoprotein oxidation is a process thought to be involved in atherogenesis. Dietary antioxidants that prevent or inhibit oxidative damage to lipoproteins may help to prevent atherosclerosis. Both black and green teas can be major dietary sources of flavonoids and other phenolics with antioxidant activity. Results of previous studies suggest that green tea may have a greater antioxidant potential than black tea. The aim of this study was to assess and compare the effects of black and green tea on in vitro lipoprotein oxidation. The tea extracts were prepared using a method similar to that used to prepare infusions of tea for drinking. Antioxidant activities of seven black teas and four green teas were assessed using an in vitro assay that measures Cu²⁺ ‐induced oxidation of lipoproteins in human serum. All tea extracts inhibited in vitro lipoprotein oxidation in human serum to a similar extent. No significant difference in antioxidant activity was found between black and green tea. Caffeine prepared to a comparable concentration to that found in tea had no effect on lipoprotein oxidation. Further studies are required to determine the importance of these findings in relation to possible protective effects of black and green tea consumption against atherogenesis and cardiovascular disease. © 1999 Society of Chemical Industry