Total Peroxyl Radical-trapping Potential Research Articles

Plasma Total Peroxyl Radical-trapping Potential in Older Type 2 Diabetes Patients Consuming Flaxseed Lignan Complex Thus Far Fails to Contribute to Decreased Plasma C-reactive Protein

Inflammation exacerbates type 2 diabetes (T2D). Decreased inflammation (as measured by plasma C-reactive protein [PCRP]) arises from increased anti-oxidant capacity. Unknown is whether plasma total peroxyl radical-trapping antioxidant potential (PTRAP) contributes to PCRP reduction in older T2D patients (OT2DP) consuming antioxidant-containing flaxseed lignan complex (FLC). The objective was to determine if PTRAP contributes to reduced PCRP in OT2DP consuming FLC.

Flaxseed Lignan Complex Consumption Thus Far Fails to Change Plasma Total Peroxyl Radical-Trapping Potential and Two LDL Oxidation Measures in Older Patients with Type 2 Diabetes—More Study Required

Plasma low-density lipoprotein(LDL) oxidation substantially exacerbates atherosclerosis in type 2 diabetes(T2D). The impact of antioxidant-containing flaxseed lignan complex (FLC) consumption on LDL fatty acid conjugated diene (LDL-CD), oxidized low-density lipoprotein protein (LDLox) and total peroxyl radical-trapping antioxidant potential (TRAP) levels has never been examined in persons with T2D. It was hypothesized that FLC relative to placebo would decrease LDL-CD and LDLox via increased TRAP levels. The objective was to test this hypothesis.

Identification and antioxidant activity of sinapic acid derivatives in Brassica napus L. seed meal extracts

Sinapic acid and its derivatives are main phenolic compounds present in rapeseed. Identification and quantitative determination of those compounds were carried out in crude extracts as well as extracts after basic and acidic hydrolysis. The total phenolic content in the crude extracts, expressed as sinapic acid equivalent, ranged from 1577 to 1705 mg/100 g for cv. Visby and Bellevue, respectively. An increase in total phenolics contents was observed in extracts after hydrolysis in comparison to crude extracts. The predominant phenolic acids in rapeseed samples were trans‐sinapic and cis‐sinapic acids. The highest concentration of sinapic acid methyl ester (2533–2702 mg/100 g) was detected in the extract after basic hydrolysis. In turn, two sinapic acid derivatives, i.e., kaempferol 3‐dihexoside‐7‐sinapoyl‐hexoside and 3‐hexoside‐7‐sinapoyl‐hexoside, were detected in the hydrolysed extracts. Total peroxyl radical‐trapping potential (TRAP) of the investigated crude extracts amounted to 20.21 and 27.05 μM Trolox Eq/g in the case of cv. Visby and Bellevue, respectively. The increase in antioxidant activity of the analyzed extracts after basic and acidic hydrolysis was probably a result of the release of free phenolic compounds from their conjugates (esters, glycosides).Practical applications: The content and qualitative composition of the phenolic compounds in rapeseed have much influence on the stability, sensory, and nutritional characteristics of the products. During oil production process phenolic compounds may be transferred into final products and inhibit lipid oxidation. Rapeseed oil, among all commercially available oils, has the highest content of phenolic compounds, especially sinapic acid and their derivatives. That is why the antioxidant activity of phenolic compounds was investigated in the presented study. Determination of polar phenolics before and after hydrolysis indicates which compounds are responsible for antioxidant effect in oils and which are available for the human organism after digestion in the digestive tract.

ANTIOXIDANT EFFECTS OF MUEHLENBECKIA HASTULATA J. (POLYGONACEAE) EXTRACTS

The antioxidant properties of different extracts of quilo (Muehlenbeckia hastulata J., Poligonaceae) herb from Valparaiso region in Chile were evaluated. Antioxidant activity was assessed in three different model systems. Antioxidant models were examined by measuring the scavenging activity of extracts on 2,2-diphenyl-1-pycrylhydrazil (DPPH●). Moreover extracts were evaluated by ferric reducing antioxidant power (FRAP) and the total peroxyl radical-trapping potential (TRAP). The amount of dried extract, the content of total phenolics, flavonoids, hydrolyzed sugar and anthraquinones were also determined. Extracts pertaining to stem and root of the plants were the significant activities DPPH radical scavenging (IC 50 0.74 mg/mL to 1.33 mg/mL the more active extracts). The activities and TRAP and FRAP high values in extracts of EtOAc (1.423 and 1.540 mM TEAC) and ethanol (245.26 and 309.04 mM TEAC) stem and root of the plant are higher.The observed differences in antioxidant activity among the different parts of quilo could be partially explained by the levels of phenolics compounds present in the root extract of EtOAc (0.023 mg GAE/g dry extract), flavonoids in the leaves of EtOAc extract (99.12 mg QE/g dry extract), hydrolyzed sugar in the ethanol extract (21.87, 14.85 and 14.32 mg GES/ g dry extract of leaf, stem and roots, respectively) and anthraquinones in the EtOAc extracts (2.50, 1.43 and 0.84 mg EE/ g dry extract of leaf, stem and roots, respectively) .

Antioxidative Status, DNA Damage and Lipid Profiles in Korean Young Adults by Glutathione S-Transferase Polymorphisms

Oxidative stress leads to the induction of cellular oxidative damage, which may cause adverse modifications of DNA, proteins, and lipids. The production of reactive species during oxidative stress contributes to the pathogenesis of many diseases. Antioxidant defenses can neutralize reactive oxygen species and protect against oxidative damage. The aim of this study was to assess the antioxidant status and the degree of DNA damage in Korean young adults using glutathione s-transferase (GST) polymorphisms. The GSTM1 and GSTT1 genotypes were characterized in 245 healthy young adults by smoking status, and their oxidative DNA damage in lymphocytes and antioxidant status were assessed by GST genotype. General characteristics were investigated by simple questionnaire. From the blood of the subjects, GST genotypes; degree of DNA damage in lymphocytes; the erythrocyte activities of superoxide dismutase, catalase, and glu- tathione peroxidase; plasma concentrations of total peroxyl radical-trapping potential (TRAP), vitamin C, α- and γ-tocopherol, α- and β-carotene and cryptoxanthin, as well as plasma lipid profiles, conjugated diene (CD), GOT, and GPT were analyzed. Of the 245 subjects studied, 23.2% were GSTM1 wild genotypes and 33.4% were GSTT1 wild gen- otype. No difference in erythrocyte activities of superoxide dismutase, catalase, or glutathione peroxidase, and the plas- ma TRAP level, CD, GOT, and GPT levels were observed between smokers and non-smokers categorized by GSTM1 or GSTT1 genotype. Plasma levels of α- and γ-tocopherol increased significantly in smokers with the GSTT1 wild geno- type (p < 0.05); however, plasma level of α-carotene decreased significantly in non-smokers with the GSTM1 wild geno- type (p < 0.05). DNA damage assessed by the Comet assay was significantly higher in non-smokers with the GSTM1 null genotype; whereas DNA damage was significantly lower in non-smokers with the GSTT1 null genotype. Total cho- lesterol and LDL cholesterol levels were significantly higher in non-smokers with the GSTT1 null genotype than those with the GSTT1 wild genotype (p < 0.05). In conclusion, the GSTM1 null genotype or the GSTT1 wild genotype in non-smokers aggravated their antioxidant status through DNA damage of lymphocytes; however, the GSTT1 wild type in non-smok- ers had normal plasma total cholesterol and LDL-cholesterol levels. This finding confirms that GST polymorphisms could be an important determinant of antioxidant status and plasma lipid profiles in non-smoking young adults. Further study is necessary to clarify the antioxidant status and/or lipid profiles of smokers with the GST polymorphism and to conduct a study with significantly more subjects. (Korean J Nutr 2011; 44(1): 16 ~ 28)

Relationship between antioxidant potential and oxidative damage to lipids, proteins and DNA in aged rats

Oxidative stress has been implicated to play a major role in aging and age-related diseases. In the present study, we investigated the effects of aging on the total antioxidant capacity, uric acid, lipid peroxidation, total sulfhydryl group content and damage to DNA in adult (6 months), old (15 months) and senescent (26 months) male Wistar rats. The antioxidant capacity, determined by phycoerythrin-based TRAP method (total peroxyl radical-trapping potential) was significantly decreased in the plasma and myocardium of old and senescent rats, whereas plasma level of uric acid was elevated in 26-month-old rats. Age-related decline in plasma and heart antioxidant capacity was accompanied by a significant loss in total sulfhydryl group content, increased lipid peroxidation and higher DNA damage in lymphocytes. Correlations between TRAP and oxidative damage to lipids, proteins and DNA suggest that the decline in antioxidant status may play an important role in age-related accumulation of cell damage caused by reactive oxygen species.

Blood Plasma Antioxidant Defense in Patients With Pancreatitis

The aim of this study was to establish the main determinants of plasma antioxidant potential in different types of human pancreatitis: chronic pancreatitis (CP, n = 19), chronic pancreatitis exacerbated (CPE, n = 16), and acute pancreatitis (AP, n = 8). We measured the plasma thiobarbituric acid reactive substances (TBARS), total peroxyl radical trapping potential (TRAP), and the levels of antioxidants such as uric acid (UA), SH groups (SH), ascorbic acid (AA), and bilirubin (BIL). In comparison to healthy volunteers (HV, n = 22) the average levels of TBARS in all types of pancreatitis were significantly higher (by 50%-90%), and plasma SH groups were lower (approximately 30%). In the multivariate regression models, the variability of plasma TRAP was explained in the HV group through UA only (36%), in the CP group through UA, AA, and BIL together (75%), and in CPE group through UA and AA together (81%). Plasma SH concentration did not enter the regression models in all groups. The AP group revealed "paradoxically" high concentrations of AA and TRAP and a negative, linear correlation between the level of TRAP versus UA concentration (R = -0.87). The multivariate regression analysis points to different structures of antioxidant defense in healthy people and those with pancreatitis: they were much the same in the CP and CPE groups but fundamentally different in the AP group. AP may activate unidentified antioxidant defenses as an adaptive response against oxidative stress.

Antioxidant properties of two novel 2-biphenylmorpholine compounds (EP2306 and EP2302) in vitro and in vivo

The oxidation of low-density lipoprotein (LDL) is an important event in the development of atherosclerosis. In the present study, the antioxidant properties of two novel 2-biphenylmorpholine compounds (EP2306 and EP2302) were studied. Both compounds inhibited dose-dependently the in vitro oxidation of LDL induced by copper ions. EP2306 and EP2302 increased significantly the lag phase of the oxidation reaction at 0.1 and 10 μM, respectively, whereas they reduced the rate of the reaction at 1 and 10 μM, respectively. This inhibitory effect was not due to a free radical scavenging or copper-chelating activity of EP2300 compounds. Moreover, EP2306 and EP2302 inhibited 12-lipoxygenase activity dose-dependently with IC 50 values of 454 and 318 μM, respectively, but had no effect on 15-lipoxygenase activity. In hyperlipidaemic rabbits treated with EP2306 for 4 weeks, there was a decrease in thiobarbituric acid-reactive substance (TBARS) levels and a significant increase in total peroxyl radical-trapping potential (TRAP) levels as compared to control animals. The present data suggest that EP2300 compounds are effective inhibitors of copper-mediated LDL oxidation in vitro. Moreover, EP2306 acts as an antioxidant in hyperlipidaemic rabbits, a property which could be beneficial in reducing atherosclerosis.

The total peroxyl radical trapping potential in serum ‐ an assay to define the stage of atherosclerosis

Lipid peroxides were identified among the factors that contribute to the atherosclerotic plaque formation in the arterial wall. We hypothesised that a correlation may exist between the content of antioxidant constituents in the serum and the gravity of atherosclerosis. To this purpose, we have determined the serum total peroxyl radical- trapping potential (TRAP), which is the combined capacity of all antioxidants to neutralize free radicals in serum and followed its variation in hyperlipemic animals in correlation with the stage of atherosclerosis. In addition, we compared TRAP values in the sera of coronary heart disease (CHD) patients, with or without type II diabetes mellitus. Results showed that after 18 weeks of hyperlipemic diet, the mean TRAP values measured in sera isolated from hyperlipemic hamsters exhibited an about 44% decrease, in good agreement with the increase of serum cholesterol and triglycerides. In the 3 groups of CHD patients, TRAP values decreased with about 10% in sera of stable angina patients, 20% in unstable patients, as compared with normal subjects. The lowest TRAP values were detected in the sera of patients with acute myocardial infarction. The results obtained for different experimental animals and for CHD patients sera indicate that the TRAP method, as adapted in our laboratory, is a reliable and reproducible assay, fit to be used in clinical studies as an ex vivo measurable parameter that correlates with the stage of the atherosclerosis.

The hyperlipemic hamster - a model for testing the anti-atherogenic effect of amlodipine.

Male Golden Syrian hamsters were subjected to a hyperlipemic diet. At intervals ranging from 2 to 14 weeks, the animals were examined for changes in serum constituents and structural modifications of lesion-prone areas: the cardiac valves, coronary arteries and aortic arch. Serum was characterized by a gradual increase in cholesterol, triglycerides and a decrease in total peroxyl-radical trapping potential. The sequence of modifications of the endothelial cells, smooth muscle cells, and migrating plasma monocytes as well as of the extracellular matrix were established. Amlodipine treatment of hyperlipemic hamster was assessed. Amlodipine exhibited an athero-protective effect, acting as antioxidant, reducing the LDL uptake by the vessel wall and consequently, limiting the size and extent of lesioned areas. The hyperlipemic hamster is a reliable model to unravel the cellular alterations leading to atheroma formation, and for testing the effect of drugs in this process.

Low plasma antioxidant activity is associated with high lesion volume and neurological impairment in stroke.

Oxidative stress is probably involved in neuronal damage induced by ischemia-reperfusion. The purpose of this study was to assess the role of antioxidant activity in cerebral ischemic stroke. Antioxidant activity of blood plasma and cerebrospinal fluid was assessed in 22 patients with cerebral hemisphere infarction that was verified and quantified by MRI. Low total peroxyl radical trapping potential of plasma, but not of cerebrospinal fluid, was associated with high lesion volume and high neurological impairment assessed by scores on NIH Stroke Scale, Barthel Index, and Hand Motor Score tests. The plasma concentrations of ascorbic acid, alpha-tocopherol, and protein thiols were also associated with the degree of neurological impairment. These data suggest that the antioxidant activity of plasma may be an important factor providing protection from neurological damage caused by stroke-associated oxidative stress.

1] Total antioxidant activity measured by chemiluminescence methods

This chapter presents detailed protocols for the measurement of chemiluminescence-enhanced total peroxyl radical-trapping potential (TRAP) of both plasma and low-density lipoprotein (LDL). The chemiluminescence-enhanced TRAP method has proven to be a reliable tool for evaluating the total activity of chain-breaking antioxidants in biological fluids. Chemiluminescence-enhanced TRAP has revealed important information in evaluating the antioxidant status of human plasma. Plasma antioxidant defenses seem to respond to needs related to the basic metabolic rate and to the challenges caused by physiological or pathological stress. According to the study, an important, possibly endogenous, antioxidant remains to be identified. However, the total antioxidative potential cannot be evaluated reliably by measuring only TRAP because of its dependence on uric acid. TRAP combined with its main components is likely to give more valid information in determining the total antioxidant status.

Antioxidant vitamin supplementation and lipid peroxidation in smokers

Previous studies have shown that cigarette smoke enhances lipid peroxidation. This study examined the effect of daily consumption of a tomato-based juice supplemented with vitamin C (600 mg), vitamin E (400 IU, or 400 mg), and b-carotene (30 mg) on various indexes of lipid peroxidation (breath pentane excretion and susceptibility of LDL to coppermediated(oxidation) in smokers. In addition, plasma lycopene and vitamin concentrations and total peroxyl radical trappingpotential, a measure of antioxidant defenses, were assessed. Relative to the placebo juice, the vitamin-supplemented juice resulted in a significant decrease in breath-pentane excretion as well as a significant improvement in the resistance of LDL to oxidation. The lag phase of conjugated diene formation lengthened and the propagation rate decreased, indicating a decreased susceptibility of LDL to oxidative modification. Increased concentrations of plasma vitamin C, b-carotene, and lycopene werefound to be significantly correlated with the conjugated diene lag phase and rate of formation. Vitamin E was highly correlated with b-carotene. Plasma total peroxyl radical trapping potential values did not change in response to supplementation. This study thus indicates that an antioxidant-supplemented drink can reduce lipid peroxidation and susceptibility of LDL to oxidation in smokers and may ameliorate the oxidative stress of cigarette smoke. Am J Clin Nutr 1998;68:319–27.

The association between the total antioxidant potential of plasma and the presence of coronary heart disease and renal dysfunction in patients with NIDDM

Oxidative stress may be an important pathogenetic factor in the development of diabetic vascular complications. The total antioxidative potential of plasma reflects the ability of an individual to resist oxidative stress. We measured the plasma total peroxyl radical-trapping potential (TRAP) and the concentrations of four plasma chain-breaking antioxidants in 81 patients with non-insulin-dependent diabetes mellitus (NIDDM) nine years after diagnosis and in 102 well-matched non-diabetic control subjects. The association between the total antioxidative potential and the presence of coronary heart disease (CHD) and diabetic kidney disease were also studied. There were no significant differences in plasma TRAP between NIDDM patients and control subjects (1250 ± 199 vs. 1224 ± 198 μM). Nor were there any significant differences in the concentrations of plasma uric acid, ascorbic acid, α-tocopherol, and protein thiols between NIDDM patients and control subjects. Patients with a low glomerular filtration rate and/or high urinary albumin excretion had elevated plasma uric acid. Plasma TRAP was not, however, associated with renal dysfunction. The plasma of NIDDM patients with CHD had a significantly higher value of unidentified antioxidative potential than that of patients without CHD. This relation was strongly dependent upon smoking. In conclusion, these data demonstrate that there are no major defects in the antioxidative potential of plasma caused by NIDDM per se. CHD and diabetic renal dysfunction were not associated with changes in plasma TRAP.

Spectrophotometric assay for total peroxyl radical-trapping antioxidant potential in human serum

Antioxidants prevent modification of low density lipoprotein (LDL) by free radicals and possibly also atheroma formation. The capacity of human serum to resist attacks by free radicals is measured by the total peroxyl radical-trapping potential (TRAP). Its measurement has thus far required equipment not available in many clinical laboratories such as a thermostated oxygen electrode cell or a luminometer. To develop a simpler method we used a free radical probe, dichlorofluorescin-diacetate (DCFH-DA), described before in studies of respiratory burst in inflammatory cells. Its oxidation by radicals from thermal decomposition of 2,2'-diazobis(2-amidinopropane)dihydrochloride (AAPH) converts this compound to highly fluorescent dichlorofluorescein (DCF). The DCF also has absorbance at 504 nm thus enabling the determination of TRAP either fluorometrically or spectrophotometrically. Increasing the concentration of AAPH enables the measurement of DCF formation and its inhibition by serum samples at room temperature. The intra- and interassay coefficients of variation of this assay are 3.4% and 4.6%, respectively. The mean value for serum TRAP of healthy subjects is 1155 mumol/l (n = 38). The TRAP in human serum can be increased by adding various antioxidant substances to the assay in vitro or by dietary supplementation of healthy subjects with vitamin E in vivo (P < 0.025). An increase was also found in serum vitamin E levels (P < 0.0001) and in the length of the time human LDL is able to resist oxidation (P < 0.05). Thus the determination of TRAP by this method, which requires only commercially available chemicals, can be used for the evaluation of phenomena associated with lipid accumulation in human artery wall.

Reduced Plasma Peroxyl Radical Trapping Capacity and Increased Susceptibility of LDL to Oxidation In Poorly Controlled IDDM

Oxidation of low-density lipoproteins (LDLs) has been postulated to play an important role in atherogenesis. Because oxidant stress may be increased and antioxidant defenses reduced in diabetes, the susceptibility of LDL to oxidative modification and total peroxyl radical trapping potential (TRAP) of plasma were evaluated in subjects with poorly controlled insulin-dependent diabetes mellitus (IDDM). The lag phase of conjugated diene formation after initiation of LDL oxidation by the addition of copper was shorter in diabetic subjects than in normal control subjects (126 +/- 11 vs. 165 +/- 15 min [means +/- SE], P < 0.05). This could not be attributed to the presence of oxidation-susceptible, small, dense LDL particles in the diabetic subjects, whose lipoprotein particle distribution did not differ from the control subjects. However, the total TRAP of plasma, a measure of antioxidant defense, was reduced (626 +/- 34 vs. 877 +/- 41 microM, P < 0.0001) in diabetes. Of the plasma antioxidants measured, only uric acid and vitamin A were decreased in diabetes (P < 0.01), and both levels correlated with TRAP (r = 0.75, P < 0.001; r = 0.54, P < 0.001, respectively). The correlation between uric acid levels and TRAP persisted when the diabetes and control groups were analyzed separately. The reduced TRAP of plasma and the increased susceptibility of LDL to oxidative modification observed is consistent with a role for lipoprotein oxidation in the pathogenesis of atherosclerosis in IDDM.