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PubMed2003

Barbituric and thiobarbituric acids: a conformational and spectroscopic study.

A conformational study on Barbituric (BA) and Thiobarbituric (TBA) acids was performed at ab initio MP2/6-31G** level on the neutral, protonated, mono- and di-anionic forms. Acid-base equilibria were studied by comparing the electronic transitions evaluated for the most stable conformations and the experimental spectra at different pH values. The electronic transitions were obtained through the ZINDO approach.

Barbiturates↗
PubMed2000

Spectral and thermal studies of thiobarbituric acid complexes.

The complexes of 2-thiobarbituric acid with Fe(II), Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) have been isolated and characterized on the basis of elemental analyses, molar conductance, magnetic moment and spectral studies. The thermal decomposition of the metal complexes was studied by TG and DTA techniques. The kinetic parameters namely, activation energy, entropy of activation and the reaction orders were estimated.

Kinetics↗
PubMed2003

Pre- and post-mortem use of grape seed extract in dark poultry meat to inhibit development of thiobarbituric acid reactive substances.

Diets containing grape seed extract (GSE)-control, GSE [low GSE, low GSE + methionine, high GSE, and high GSE + methionine], or alpha-tocopherol-were fed to broiler chicks to estimate the antioxidative activity of GSE in processed meat. GSE was detrimental to the growth of chicks, and methionine did not reverse the detrimental effect. GSE with 85.4 g of gallic acid equiv/100 g (GAE 85.4) was added to ground dark turkey meat to obtain treatments with no GSE, 1.0% GSE, and 2.0% GSE and then processed as unsalted or salted and unheated or heated. Processed treatments were analyzed for thiobarbituric acid reactive substances (TBARS) and percent expressible moisture (%EM). GSE at 1.0 and 2.0% decreased TBARS values nearly 10-fold as compared to the control. GSE (1.0%) had a %EM value significantly greater than that of the control. GAE 85.4 decreased TBARS values more than GAE 88.9.

Animals↗
PubMed2004

Effect of electron beam irradiation and storage at 5 degrees C on thiobarbituric acid reactive substances and carbonyl contents in chicken breast meat infused with antioxidants and selected plant extracts.

This study evaluated the effectiveness of synthetic and natural antioxidants, green tea, commercial grape seed extracts/combinations, and TBHQ, with varying concentrations of lipid oxidation of nonirradiated and irradiated chicken breast meats stored at 5 degrees C for 12 days. Fresh boneless and skinless chicken breast meats were vacuum-infused with varying concentrations of antioxidants: green tea, grape seed extracts alone/in combination, and TBHQ. The irradiation dosage was 3.0 kGy. Carbonyl values of raw chicken meat and thiobarbituric acid reactive substances (TBARS) values of raw and cooked chicken meat were determined for 0-12 days at 5 degrees C storage. TBARS values for 0-12 days of storage at 5 degrees C ranged from 1.21 to 7.3 and 1.22 to 8.51 mg malondialdehyde/100 g chicken for nonirradiated and irradiated raw chicken, respectively. TBARS values of cooked chicken ranged from 2.19 to 35.83 and 2.45 to 45.72 mg malondialdehyde/100 g chicken for nonirradiated and irradiated chicken, respectively. Irradiation increased TBARS values of both controls and plant extracts. The carbonyl content in meat lipid ranged from 1.7 to 2.9 and 1.7 to 4.41 micromol acetophenone/10 g of nonirradiated and irradiated chicken meat, respectively, and meat protein ranged from 1.4 to 2.07 and 1.41 to 2.72 micromol/10 g meat. Infusion of chicken meat with selected plant extracts is an effective method to minimize lipid oxidation and volatiles developments caused by irradiation.

Acetophenones↗
PubMed1999

Determination of sialic acid by the thiobarbituric acid reaction in sweet whey and its fractions.

Determination of sialic acid in sweet whey is useful as the concentration of sialic acid reflects the amount of glycomacropeptide (GMP) present. In this study, the concentration of total sialic acid was determined by the thiobarbituric acid reaction after dialysis of samples in water, and the concentration of GMP sialic acid was estimated by gel chromatography on Sephacryl S-200. Concentrations of total and GMP sialic acid determined in a sweet whey sample prepared from fresh milk were 2.0 and 1.5 microg/mg of dry weight, respectively. Analysis of commercial samples showed that the concentration of total sialic acid in sweet whey was 9 times lower than that in whey protein concentrate but 18 times higher than that in whey permeate. A similar trend was observed in the variation of GMP sialic acid concentration between sweet whey and why protein concentrate. The concentration of sialic acid differed 10 times between two samples of whey protein isolate.

Chromatography, Gel↗
PubMed2000

Measurement of 2-thiobarbituric acid values in dark chicken meat through derivative spectrophotometry: influence of various parameters.

Several variables (kind of filter paper, amount of sample, antioxidant addition, stability of the spectrophotometric measurement, and handling and storage of samples) were found to influence 2-thiobarbituric acid (TBA) values in dark chicken meat when an acid aqueous extraction method with derivative spectrophotometry was used. Filter papers with larger pore diameter or increasing sample weight led to lower TBA values. After incubation of reaction mixtures at 70 degrees C and ice-cooling, tempering for 45 min at room temperature was necessary to stabilize the spectrophotometric measurement. Furthermore, addition of butylated hydroxytoluene (BHT) and ethylenediaminetetraacetic acid disodium salt (EDTA) in the early steps of the method prevented artifactual formation of TBA reactive substances during analysis. Vacuum packaging and storage of samples at -20 degrees C were useful to avoid sample oxidation. The method finally proposed has a coefficient of variation of 3.81 or 4.13% for raw or cooked samples, respectively.

Animals↗
PubMed2000

Effect of chronic variate stress on thiobarbituric-acid reactive species and on total radical-trapping potential in distinct regions of rat brain.

It has been suggested that oxidative stress is involved in aging and neuropathologic disorders. In addition, chronic stress and high corticosterone levels are suggested to induce neuronal death. The aim of this study is to verify the effect of chronic variate stress on lipoperoxidation and on the total radical-trapping potential (TRAP) in hippocampus, hypothalamus and cerebral cortex. Adult male Wistar rats were submitted to different stressors during 40 days. Lipid peroxide levels were assessed by the thiobarbituric acid reactive species (TBARS) reaction, and TRAP was measured by the decrease in luminescence using the 2-2'-azo-bis(2-amidinopropane)-luminol system. The results showed that in cerebral cortex homogenates chronic stress induces an increase in oxidative stress. In hypothalamus a decreased lipoperoxidation was observed, however TRAP showed no difference. In hippocampus no difference was observed. We concluded that prolonged stress induces oxidative stress which varies selectively with the brain region.

Animals↗
PubMed1989

Spectrophotometric method for the determination of sorbic acid in various food samples with iron(III) and 2-thiobarbituric acid as reagents.

A simple, rapid and accurate spectrophotometric method has been developed for the determination of sorbic acid in various food samples based on the oxidation of sorbic acid by iron(III) at 100 degrees C to malonaldehyde, which then reacts with 2-thiobarbituric acid to form a reddish brown product. The optimum experimental conditions for colour development have been assessed. Absorbance measurements were made at 529 nm in the presence of 0.4% m/V citric acid. The calibration graph was linear for 0-6 micrograms ml-1 of sorbic acid with a slope of 0.131 A micrograms-1 ml. The recoveries of sorbic acid at concentrations of 164-557 micrograms ml-1 ranged from 96 to 103%. The relative standard deviations of ten replicate determinations of sorbic acid in a synthetic cream soda sample spiked with 573 micrograms ml-1 of sorbic acid and in an onion juice sample containing 82 micrograms ml-1 of sorbic acid were 1.6 and 1.9%, respectively. Interferences from several common food additives can be minimised by extracting sorbic acid with diethyl ether and then back-extracting the acid with sodium hydrogen carbonate. The method has been applied successfully to the determination of sorbic acid in a wide range of food samples including beverages, cake, cake mate, garlic bread sprinkle, onion juice, oyster flavoured sauce and grenadine syrup.

Fatty Acids, Unsaturated↗
PubMed1993

Determination of malonaldehyde in human plasma: elimination of spectral interferences in the 2-thiobarbituric acid reaction.

A selective, derivative spectrophotometric method has been developed for the determination of malonaldehyde (MLD), based on a reaction with 2-thiobarbituric acid (TBA). The proposed method has been applied to the determination of MLD in human plasma. A study to eliminate several spectral interferences is described. A comparative study of the results obtained using the proposed derivative method and a conventional TBA method applied to human plasma is presented and the advantages of the proposed method over the conventional method for the determination of MLD in human plasma are evaluated.

Humans↗
PubMed1984

Reactivity of hydroxyl and hydroxyl-like radicals discriminated by release of thiobarbituric acid-reactive material from deoxy sugars, nucleosides and benzoate.

Hydroxyl radicals (OH.) can be formed in aqueous solution by a superoxide (O2.-)-generating system in the presence of a ferric salt or in a reaction independent of O2.- by the direct addition of a ferrous salt. OH. damage was detected in the present work by the release of thiobarbituric acid-reactive material from deoxy sugars, nucleosides and benzoate. The carbohydrates deoxyribose, deoxygalactose and deoxyglucose were substantially degraded by the iron(II) salt and the iron(III) salt in the presence of an O2.- -generating system, whereas deoxyinosine, deoxyadenosine and benzoate were not. Addition of EDTA to the reaction systems producing radicals greatly enhanced damage to deoxyribose, deoxyinosine, deoxyadenosine and benzoate, but decreased damage to deoxygalactose and deoxyglucose. Further, OH. scavengers were effective inhibitors only when EDTA was present. Inhibition by catalase and desferrioxamine confirmed that H2O2 and iron salts were essential for these reactions. The results suggest that, in the absence of EDTA, iron ions bind to the carbohydrate detector molecules and bring about a site-specific reaction on the molecule. This reaction is poorly inhibited by most OH. scavengers, but is strongly inhibited by scavengers such as mannitol, glucose and thiourea, which can themselves bind iron ions, albeit weakly. In the presence of EDTA, however, iron is removed from these binding sites to produce OH. in 'free' solution. These can be readily intercepted by the addition of OH. scavengers.

Benzoates↗
PubMed1984

Lipid peroxidation in rheumatoid arthritis: thiobarbituric acid-reactive material and catalytic iron salts in synovial fluid from rheumatoid patients.

Thiobarbituric acid (TBA)-reactive material is present in serum and knee joint synovial fluid from rheumatoid patients, consistent with lipid peroxidation occurring in vivo. The amount of TBA-reactive material in synovial fluid correlates with the concentration of iron salts present as determined by the bleomycin method, presumably because iron is an important catalyst of radical reactions in vivo. There appear to be significant correlations between the contents of TBA-reactive material and bleomycin-detectable iron in synovial fluid and the activity of rheumatoid arthritis as assessed with a clinical index of local inflammation and with various laboratory parameters.

Arthritis, Rheumatoid↗
PubMed1991

Role of glucocorticoids and catecholamines on hepatic thiobarbituric acid reactants in basal and stress conditions in the rat.

Thiobarbituric acid-reactants (TBARs) are considered to be an index of lipid peroxidation. In the present experiments, the effect of stress and hormones on hepatic TBARs levels was studied in Sprague-Dawley rats. In unstressed conditions adrenalectomized rats showed higher TBARs levels than sham-adrenalectomized rats. The effect of adrenalectomy was reverted by the administration of corticosterone but not by that of aldosterone, indicating that glucocorticoids exert a negative role on the regulation of liver TBARs. The effect of these hormones appears to be a permissive one, since the administration of a long lasting ACTH preparation did not reduce liver TBARs. In contrast to that observed in unstressed rats, glucocorticoids appeared to increase liver TBARs in stressed rats. Nevertheless, other alternative explanations are possible. Finally, no evidence for a role of catecholamines in the regulation of hepatic TBARs was found.

Adrenalectomy↗
PubMed1998

The effect of a low carotenoid diet on malondialdehyde-thiobarbituric acid (MDA-TBA) concentrations in women: a placebo-controlled double-blind study.

OBJECTIVE: The purpose of the study was to evaluate the effect of a low carotenoid diet (83 micrograms Beta-carotene) on malondialdehyde-thiobarbituric acid (MDA-TBA) concentrations of nine pre-menopausal women. METHODS: Subjects lived on the metabolic research unit of the Western Human Nutrition Research Center (WHNRC), where diet, exercise and other activities were controlled. Five subjects (Group C, control group) consumed a low carotenoid diet and received an additional 0.5 mg/day of Beta-carotene while four subjects (Group P, placebo group) received only the low carotenoid diet during days 1 to 60 (period 1). All subjects received 0.5 mg/day of Beta-carotene during days 60 to 100 (period 2), plus three capsules/day mixed carotenoid supplement (Neo-Life Company) during study days 100 to 120. Changes in MDA-TBA concentrations were analyzed during the study periods and between the groups. RESULTS: At the start of the study (day 1), no significant difference in the MDA-TBA concentration was observed between the control (Group C) and the placebo (Group P) subjects. During period 1 (days 2 to 60), when Group P subjects consumed the low carotenoid diet without supplementation, the MDA-TBA values for Group P rose markedly and were significantly (p < 0.05) higher than the MDA-TBA values for Group C subjects who were receiving carotenoid supplementation. During period 2 (days 60 to 100) when both groups received carotenoid supplementation, the MDA-TBA values of Group P subjects were significantly (p < 0.05) reduced to the point where they were similar to the MDA-TBA values for Group C subjects. CONCLUSIONS: These findings provide evidence to support the beneficial effects of carotenoids in preventing lipid peroxidation in the cells. Further studies are needed to identify the exact mechanism by which carotenoids prevent lipid peroxidation and the amount needed for normal activity.

Adult↗
PubMed2004

Hyperhomocysteinemia, enzyme polymorphism and thiobarbituric Acid reactive system in children with high coronary risk family history.

OBJECTIVES: To investigate both the frequency and the genetic background of hyperhomocysteinemia and the frequency of increased plasma thiobarbituric acid reactive system (TBARS) levels in children and adolescents whose parents had premature coronary heart disease (CHD). METHODS: The study was performed on children and adolescents aged 4-18 years (105 offspring of parents with CHD before age 45 and 74 referents from families without any evidence of premature atherosclerosis). Fasting serum total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), and total triglyceride (TG) levels were measured by enzymatic methods. Low density lipoprotein cholesterol (LDL-C) level was calculated by the Friedewald formula. Plasma total homocysteine (THCy) level was measured by fluorescence polarisation immunoassay. Plasma TBARS level was determined by fluorimetric method. 5,10-methylenetetrahydrofolate reductase (MTHFR) enzyme polymorphism was analyzed by polymerase chain reaction with restriction fragment length polymorphism (PCR-RFLP). RESULTS: Hyperhomocysteinemia was found in 32 cases and in 4 controls. Increased plasma THCy level was found in 10 children and adolescents from 12 cases homozygous for the C677T polymorphism of the MTHFR gene. No similar high frequency was observed in heterozygous subjects. Elevated fasting plasma TBARS levels were found in 38 cases and in 8 controls. The frequency differences were significant (p < 0.01). Allele frequency of the MTHFR polymorphism among cases and controls was similar. Significant correlation (r = 0.53, p < 0.02) was detected between plasma THCy and TBARS levels. One child had high serum TC level, 5 had low serum HDL-C level and all other children had normal serum TC, LDL-C, HDL-C and TG levels from children with hyperhomocysteinemia and/or high plasma TBARS levels. A significant correlation (r = 0.64, p < 0.01) was observed between plasma THCy levels of parents and children in the case group. CONCLUSION: The measurement of plasma THCy and TBARS levels may contribute to the detection of the risk of children and adolescents with high CHD risk family history.

Adolescent↗
PubMed1998

The thiobarbituric acid (TBA) reaction in foods: a review.

The wide diffusion of 2-thiobarbituric acid (TBA) in the scientific literature is due to the TBA assay, or TBA test, which has been employed in the determination of autoxidative alterations of fats and oils. Two processes occur in autoxidation, generally: the free radical and the photo-oxidation mechanisms. The better studied is the free radical mechanism. The hydroperoxiepidioxides and bicycloendoperoxides are malonaldehyde (MDA) precursors. The absorption spectrum obtained with oxidized fatty foods is like the spectrum obtained when TBA and MDA react. However, during the secondary phase of the autoxidation process other aldehydes (alkanals, 2-alkenals, dienals) are formed which react with TBA, and they are responsible for off-flavors. Three kinds of pigments (yellow, orange, red adducts) are involved. Also, aromatic aldehydes, which constitute the flavor profile of diverse fruits and essential oils, form with TBA the characteristic arylidene-2-TBA acids. Other substances, such as ketones, ketosteroids, acids, esters, sugars, imides and amides, amino acids, oxidized proteins, pyridines, pyrimidines, and vitamins can react with TBA; they are named TBARS (substances that react with TBA), and form principally in meats and meat derivatives. Several organic or bio-organic acids, as shikimic and sorbic acids, react photometrically with TBA if a Malaprade reaction takes place before. A structural study of the red adduct TBA-MDA has been carried out.

Aldehydes↗
PubMed1995

Effect of oxygen concentration on production of ethane and thiobarbituric acid-reactive substances by peroxidizing lung and liver homogenates and formation of ethanol by peroxidizing docosahexaenoic acid preparations under hyperoxic conditions.

The oxygen dependence of ethane formation was investigated in rat lung and liver homogenates, incubated in sealed flasks, in which the peroxidation was stimulated by the addition of ferrous ions. For both tissues, the production of ethane was maximal under a 20% oxygenated gas phase, while hyperoxic conditions led to a decreased ethane in the gas phase. The formation of thiobarbituric acid-reactive substances (TBA-RS), another marker of the lipid peroxidation process, in the homogenates of lung and liver was strongly stimulated at 100% compared to 20% oxygen. Experiments were also carried out on iron-stimulated peroxidation of pure docosahexaenoic acid preparations, which under air led to a large production of ethane. As for tissue homogenates, the TBA-RS content was increased in the presence of 100% oxygen. Those conditions, however, did not induce an increase in ethane production but led to the formation of ethanol. Therefore, the quenching of ethyl radical by molecular oxygen seems to be a very attractive hypothesis to explain the lack of increased ethane production in favor of ethanol when iron-induced lipid peroxidation was stimulated by oxygen.

Animals↗
PubMed1994

Prevention by acetylsalicylic acid of liver cirrhosis and carcinogenesis as well as generations of 8-hydroxydeoxyguanosine and thiobarbituric acid-reactive substances caused by a choline-deficient, L-amino acid-defined diet in rats.

Effects of acetylsalicylic acid (ASA) (aspirin) on the pathogenesis of fatty liver, cirrhosis and hepatocarcinogenesis caused by a choline-deficient L-amino acid-defined (CDAA) diet were examined in male Fischer 344 rats fed a CDAA diet supplemented with 0, 0.1, 0.2, 0.4 or 0.8% ASA for 30 weeks. ASA at concentrations of > 0.2% prevented the development of both cirrhosis and preneoplastic and neoplastic nodules, but without any directly associated prevention of fatty changes. ASA also prevented hepatocyte proliferation and the generation of thiobarbituric acid-reactive substances and 8-hydroxydeoxyguanosine caused by feeding the CDAA diet, analyzed, respectively, after 1, 12 and 12 weeks. The results clearly indicate that the anti-inflammatory drug ASA, which is not a lipotropic factor, can prevent the pathogenesis of cirrhosis and hepatocarcinogenesis caused by a CDAA diet, which is possibly partly associated with the prevention of reactive oxygen species production.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1978

Micro determination of unsaturated disaccharide formed by the action of acidic glycosaminoglycan-endoeliminases. An application of the thiobarbituric acid method to the assay of D-gluco-4-enepyranosyluronic acid-containing disaccharides.

An improved method is described for the micro determination of acidic glycosaminoglycans after digestion with chondroitinase-ABC and -AC. The determination is based on the color production of D-gluco-4-enepyranosyluronic acid-containing disaccharides produced by the action of chondroitinase-ABC and -AC (acidic glycosaminoglycans-endoeliminase) when the periodate-thiobarbituric acid method is applied to the alpha,beta-unsaturated disaccharides. Suitable conditions for the quantitative assay are described.

Chondroitin Sulfates↗