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Antioxidant Function (antioxidant + function)
Selected AbstractsHEALTH BENEFITS OF APPLE PHENOLICS FROM POSTHARVEST STAGES FOR POTENTIAL TYPE 2 DIABETES MANAGEMENT USING IN VITRO MODELSJOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2010I. ADYANTHAYA ABSTRACT An increasing number of studies indicate that regular intake of fruits and vegetables have clear links to reduced risk of chronic diseases like diabetes and cardiovascular disease. The beneficial effects in many cases have been attributed to the phenolic and antioxidant content of the fruits and vegetables. Apples are a major source of fiber and contain good dietary phenolics with antioxidant function. Previous epidemiological studies have indicated that intake of apples reduces the risk of developing type 2 diabetes. Our studies indicate that this reduced risk is potentially because of the modulation of postprandial glucose increase by phenolics present in apples via inhibition of, -glucosidase. Phenolic content was evaluated during 3 months of postharvest storage of four varieties of apples and results indicated positive linkage to enhanced postharvest preservation and, -glucosidase inhibition. These in vitro results along with existing epidemiological studies provide strong biochemical rationale for further animal or human clinical studies. PRACTICAL APPLICATIONS The understanding of phenolic-linked antioxidant enzyme responses during postharvest storage of apples has implications for using the same phenolic functional ingredients toward health benefits such as ,-glucosidase inhibition linked to glycemic index control associated with type 2 diabetes. Therefore strategies to understand phenolic-linked postharvest preservation and natural treatments to extend this preservation in selected varieties, such as McIntosh and Cortland in this study, can be basis for food ingredient design for health benefits. These strategies can then be extended to prolong postharvest preservation and enhance phenolic linked human health benefits of a wide variety of fruits and vegetables. [source] Melatonin, a potent regulator of hemeoxygenase-1, reduces cardiopulmonary bypass-induced renal damage in ratsJOURNAL OF PINEAL RESEARCH, Issue 3 2009Zhongqiu Wang Abstract:, Acute renal dysfunction is a frequent complication after cardiac surgery with cardiopulmonary bypass (CPB). This study was designed to evaluate the potential protective effect of melatonin on CPB-induced renal damage in a rat model. Forty male Sprague,Dawley rats were randomly divided into four groups: sham, control (CPB + placebo), low dose of melatonin (CPB + 10 mg/kg melatonin) and high dose of melatonin (CPB + 20 mg/kg melatonin). Blood samples were collected at the beginning, at the end of CPB, and at 0.5, 1, 2, 3, and 24 hr postoperation. Serum creatinine and blood urea nitrogen levels were assayed. Rats were killed 24 hr after surgery, the histologic appearance of the kidney and malondialdehyde (MDA), myeloperoxidase (MPO), catalase (CAT) and superoxide dismutase (SOD) contents were determined. The expression levels of hemeoxygenase-1 (HO-1) protein and gene were determined using western blotting and real-time PCR, respectively. In the control group, CPB surgery significantly increased urea, creatinine levels in serum, MDA and MPO levels in tissues, while decreasing SOD and CAT activities in tissues. Histopathologic findings of the control group confirmed that there was renal impairment by cast formation and tubular necrosis in the tubular epithelium. These changes were markedly reversed in both low dose of melatonin and high dose of melatonin groups. Furthermore, HO-1 gene transcript and protein were significantly upregulated in the kidney tissues after melatonin treatment compared with the placebo treatment. Our findings show that melatonin was effective in preventing CPB-induced renal damage probably through its antioxidant function and upregulation of HO-1. [source] Photobleaching of Melanosomes from Retinal Pigment Epithelium: I. Effects on Protein OxidationPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Janice M. Burke ABSTRACT Melanin in the long-lived melanosomes of the retinal pigment epithelium (RPE) may undergo photobleaching with aging, which appears to diminish the antioxidant function of melanin and could make photobleached melanosomes less efficient in protecting biomolecules from oxidative modification. Here we analyzed whether photobleaching of melanosomes affects their ability to modify the oxidation state of nearby protein. As conventional methods developed to study soluble antioxidants are not well suited for analysis of granules such as melanosomes, we developed a new analytic method to focus on particle surfaces that involves experimentally coating granules with the cytoskeletal protein ,-actin to serve as a reporter for local protein oxidation. Isolated porcine RPE melanosomes were photobleached with visible light to simulate aging, then photobleached melanosomes, untreated melanosomes and control particles (black latex beads) were actin coated and illuminated in a photosensitized cell free system. Protein was re-stripped from particles and analyzed for carbonylation by Western blotting. Quantitative densitometry showed no reproducible differences for protein associated with untreated melanosomes when compared with control particles. Melanin has both anti- and pro-oxidant functions when light irradiated, but neither of these functions predominated in the protein oxidation assay when untreated melanosomes were used. However, protein extracted from photobleached melanosomes showed markedly increased carbonylation, both of associated actin and of endogenous melanosomal protein(s), and the effect increased with extent of granule photobleaching. Photobleaching of RPE melanosomes therefore changes the oxidation state of protein endogenous to the organelle and reduces the ability of the granule to modify the oxidation of exogenous protein near the particle surface. The results support the growing body of evidence that photobleaching of RPE melanosomes, which is believed to occur with aging, changes the physicochemical properties of the organelle and reduces the likelihood that the granules perform an antioxidant function. [source] Photobleaching of Melanosomes from Retinal Pigment Epithelium: II.PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2007Effects on the Response of Living Cells to Photic Stress Melanosomes of the retinal pigment epithelium (RPE) are long lived organelles that may undergo photobleaching with aging, which can diminish the antioxidant efficiency of melanin. Here, isolated porcine RPE melanosomes were experimentally photobleached with visible light to simulate aging and compared with untreated granules or control particles (black latex beads) for their effects on the survival of photically stressed ARPE-19 cultures. Particles were delivered to cultures for uptake by phagocytosis then cells were exposed to violet light and analyzed by a new live cell imaging method to identify the time of apoptotic blebbing as a dynamic measure of reduced cell survival. Results indicated that untreated melanosomes did not decrease photic injury to ARPE-19 cells when compared with cells lacking particles or with cells containing control particles, as might be expected if melanin performed an antioxidant function. Instead cells with untreated melanosomes showed reduced survival indicated by an earlier onset of blebbing and a lower fraction of surviving cells after photic stress. Cell survival was reduced even further in stressed cells containing melanosomes that were photobleached, and survival decreased with increasing photobleaching time. Photobleaching of RPE melanosomes therefore makes cells containing them more sensitive to light-induced cytotoxicity. This observation raises the possibility that aged melanosomes increase RPE cell photic stress in situ, perhaps contributing to reduced tissue function and to degeneration of the adjacent retina that the RPE supports. How melanosomes (photobleached or not) interact with their local subcellular environment to modify RPE cell survival is poorly understood and is likely determined by the physicochemical state of the granule and its constituent melanin. The live cell imaging method introduced here, which permitted detection of a graded effect of photobleaching, provides a sensitive bioassay for probing the effects of melanosome modifications. [source] Serum iron and copper status and oxidative stress in severe and mild preeclampsiaCELL BIOCHEMISTRY AND FUNCTION, Issue 3 2006Zehra Serdar Abstract Our aim was to investigate parameters of iron and copper status and oxidative stress and antioxidant function in women with healthy pregnancy, mild and severe preeclampsia with a view to exploring the possible contribution of these parameters to the aetiology. Thirty healthy, 30 mild preeclamptic and 30 severe preeclamptic pregnant women were included. Serum and placental lipid peroxides, and serum vitamin E and total carotene levels were measured by colorimetric assay. Cholesterol, copper, iron, total iron binding capacity (TIBC), ceruloplasmin and transferrin concentrations were measured by commercially available procedures. Data were analysed statistically using one-way analysis of variance and Pearson correlation test. Logistic regression procedures were used to calculate odds ratios. Lipid peroxides in serum and placental tissue, and iron, copper and ceruloplasmin levels in serum were significantly increased, and transferrin, TIBC, vitamin E/total cholesterol and total carotene/total cholesterol ratios in serum were significantly decreased especially in women with severe preeclampsia. Significant correlations were detected between serum iron and lipid peroxidesin serum and placental tissue and between serum iron and vitamin E/total cholesterol in severe preeclamptic pregnancy. Furthermore, there were significant correlations between serum malondialdehyde and ceruloplasmin and vitamin E/total cholesterol in women with severe preeclampsia, and changes in serum and placental lipid peroxides and serumiron concentrations were significantly associated with preeclampsia. In conclusion, ischaemic placental tissue may be a primary source of potentially toxic iron in preeclampsia and the released iron species may contribute to the aetiology and would exacerbatelipid peroxidation and endothelial cell injury, which may be abated by antioxidant supplementation. Copyright © 2005 John Wiley & Sons, Ltd. [source] Electron- and Energy-Transfer Properties of Hydrophilic CarotenoidsCHEMISTRY - A EUROPEAN JOURNAL, Issue 16 2007Hans-Richard Sliwka Abstract The antioxidant activities,expressed as the electron-donating properties,of five hydrophilic carotenoids (carotenoid surfactants) and three related hydrophobic carotenoids were investigated by flash photolysis. The electron-transfer rates of the carotenoids to the triplet state of the sensitizer 2-nitronaphthalene and the energy transfer rates of triplet 2-nitronaphthalene to the carotenoids were determined. The results demonstrate that the electron-donating effects of the hydrophilic and hydrophobic carotenoids were comparable when evaluated in acetonitrile. In the presence of water, however, electron transfer (i.e., antioxidant efficiency) was enhanced by a factor of four for the hydrophilic carotenoids. The increased hydrophilicity of carotenoids, therefore, could expand their antioxidant properties, thus facilitating their use as aqueous-phase radical scavengers. At the same time, it was shown that supramolecular assembly ("aggregation") of the amphiphilic carotenoids prevented electron transfer, thus deactivating the antioxidant function. Modulation of the biophysical properties of carotenoids through synthetic modification is capable of increasing the biological and medical utility of this natural class of predominantly hydrophobic antioxidant compound. [source] Anticipation of Acute Stress in Isoprenaline-Sensitive and , Resistant Rats: Strain and Gender DifferencesBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 4 2000Anna Yamamotová The effect of stress anticipation was studied in two inbred Wistar rat strains with high and low sensitivity to isoprenaline. The animals were exposed to tail-flick and 4-hr water immersion restraint stress on two consecutive days. On the first day stress was applied to one group and the next day to the anticipation group. The changes in adrenal, heart and spleen weights, tail-flick latency, incidence of gastric ulcers, and the antioxidant defense system in the sensorimotor cortex were compared with two non-stressed control groups. Anticipatory stress decreased adrenal weights. The content of thiobarbituric acid reactive substances (TBARS) was increased both in acute and anticipatory stress; superoxide dismutase, glutathione peroxidase, and antioxidative capacity were increased in anticipatory stress only. Stress anticipation decreased the pain threshold in the isoprenaline-sensitive and increased in the isoprenaline-resistant rats and led to more frequent gastric ulcers in the isoprenaline-resistant group. Significant sex differences were observed both in adrenal weights and TBARS content. The relative adrenal weights were negatively correlated with the TBARS content. We suggest that the outcome of anticipatory stress may depend upon the relation between the hormonal and antioxidant functions of the adrenals and that anticipation-induced activation of antioxidant enzymes may ameliorate the acute stress response. Anticipation itself was found to be a stronger stressor than physical acute stress. [source] | |||||||||||||