Thiobarbituric acid, reaction with

This test is used for both in vitro and in vivo determinations. It involves reacting thiobarbituric acid (TBA) with malondialdehyde (MDA), produced by lipid hydroperoxide decomposition, to form a red chromophore with peak absorbance at 532 nm (Fig. 10.1). The TBARS reaction is not specific. Many other substances, including other alkanals, proteins, sucrose, or urea, may react with TBA to form colored species that can interfere with this assay. 

Arylidenebarbituric and thiobarbituric acids react with compounds containing an active methylene group under Michael reaction conditions.246,247 Compounds 69 (R = H, p-N02, p-Cl X = O, S) have been obtained in the reaction of 5-arylidenebarbituric or thiobarbituric acids with cyclohexanone, benzyl phenyl ketone, camphor, ethyl ester of phenylacetic acid, or nitromethane. The reaction with ethyl cyanoacetate or ethyl... 

V. S. Waravdekar and L. D. Saslaw, A sensitive colorimetric method for the estimation of 2-deoxy sugars with the use of the malonaldehyde-thiobarbituric acid reaction, J. Biol. Chem., 234 (1959) 1945-1950. 

We have used the thiobarbituric acid reaction to measure the steady state level of lipid peroxidation products accumulating in vivo in vital organs and subcellular particles (Zalkin and Tappel, 1960 Zalkin et al., 1960). Some of these results in terms of equivalent peroxide and free radicals are shown in Table II, where they are compared in amount with known toxicity of lipid peroxides and the lethality of ionizing radiations. Advantages and limitations of the thiobarbitiuic acid have been discussed previously. Comparison of the amounts of lipid peroxides found in vitamin E-deficient animals with the known lethality of ionizing radiation and... 

The chemistry and analysis of sialic acids have been reviewed. Picomole quantities of sialic acids have been measured by the fluorescence produced by the periodate-oxidized acid in the thiobarbituric acid reaction. " Contamination of the sialic acids with 2-deoxy-D-eryt/iro-pentose (derived from cellular material) could be detected by a downfield shift of the excitation maximum. Fluorescent derivatives are also produced when free sialic acids react with pyridoxamine, a procedure that compares favourably with the thiobarbituric acid reaction for determining sialic acids. Keto-acids e.g. pyruvic acid) interfere with the determination, but 2-deoxy-D-arabmo-hexose and 2-deoxy-D-c/-ytliro-pentose do not. A nonfading chromophore is produced when DMSO is used instead of n-butanol in the thiobarbituric acid ssay for sialic acids. A new histochemical method for the visualization and identification of unmodified or 0-acylated sialic acids has been reported. ... 

The viscous reaction mixture is then poured into 1.5 liters of ice water and agitated to form a uniform solution. The solution is treated with activated carbon and filtered. Thereafter, 80% acetic acid is added until the filtered solution remains acidic to litmus. The precipitate formed is filtered and washed thoroughly with distilled water. The product is air-dried at a temperature of 95° to 100°C for 48 hours to yield 133 grams of 5-allyl-5-(1-methylbutyl)-2-thiobarbituric acid having a melting point of 132° to 133°C and assaying at 99.5% pure, from U.S. Patent 2,876,225. 

Despite the above-mentioned short-comings, this approach to the estimation of those deoxy sugars which yield malonaldehyde when oxidized with periodate, seemed promising, since, as has been seen (58,59), the dye is formed quantitatively in the reaction of malonaldehyde with 2-thiobarbituric acid also, more recently, its constitution (49,57) and molar extinction coefficient (36) have been established. Thus, if conditions could be found in which malonaldehyde, while being formed quantitatively from the deoxy sugars, would be stable, an ideal method, independent of standard compounds, would be available for the quantitative determination of all of these sugars. 

When 1, 3, 3-triethoxypropene was hydrolyzed with IN sulfuric acid, a solution of malonaldehyde whose optical density was perfectly stable at 350 m/x for at least one week was obtained. If the solution was made alkaline, the optical density at the same wavelength increased by a small value and then remained virtually constant for at least one week (56). It was also observed that in these solutions the extinction coefficient at 350 m/x was very low (observed 8.3, 61.5 and 69, for solutions of pH 0.4, 7.15 and 9.4 respectively) compared with previously reported values which varied from 200 ( 40) to 1000 ( 48). On the other hand, the absorption of solutions having a pH of 3 to 5, increased considerably with time (at pH 4.75, the extinction coefficient of malonaldehyde at 350 m/x was initially about 40 after four weeks a value of about 930 was recorded and the optical density of the solution was still increasing). This increase in absorption was accompanied by a marked decrease in the malonaldehyde content of the solution, as measured by the thiobarbituric acid method. As a corollary, it was found that aqueous solutions of malonaldehyde, prepared by autocatalyzed hydrolysis (33) of the same acetal and which had a pH of about 3.5, showed, at the completion of the hydrolysis, considerably higher extinction coefficient values at 350 m/x than did those malonaldehyde solutions which were prepared by hydrolysis with IN acid and subsequently adjusted to pH 4. It appears, therefore, that at pH values at which most of the periodate oxidations are carried out, malonaldehyde is unstable and undergoes a chemical reaction, the nature of which is not, as yet, known. 

The simple spectrophotometric thiobarbituric acid (TBA) test has been frequently used for many years as an indicator of the peroxidation of PUFAs present in biological matrices. This test involves the reaction of aldehydes in the sample with TBA at c. 100°C under acidic conditions (Equation 1.13) to produce a pink-coloured chromogen, which absorbs light strongly at a wavelength of 532 nm (Nair and Turner, 1984). 

Evidence that oxidized lipids play a role in the pathogenesis of RA comes from studies demonstrating the presence of lipid products arising from radical attack in rheumatoid synovial fluid. This is consistent with oxidation reactions occurring locally in the joint. Lipid peroxidation products that react with thiobarbituric acid (TBARs) have been detected in rheumatoid knee-joint synovial fluid (Rowley et /., 1984). In addition, the... 

The cyclizations to obtain cyclic thioureas have been performed using thiocarbonyldiimidazole.232 Reaction of methyl acetoacetate, thiourea and an aliphatic aldehyde in the presence of the zinc iodide (Znl2) was studied. Under the normal pressure, reaction has not been occurred whereas at high pressure (300 MPa) conditions 3,4-dihydropyrimidine-2-thione was obtained only in 10% yield.233 The same one-pot three-component cyclocondensation reaction in the presence of iodide (I2) provides a variety of 3,4-dihydropyrimi-dine-2-thione in high yields.234 Condensation reaction of thioureas with a,p-unsaturated ketones in the presence of the sodium methoxide in methanol affords 3,4-dihydropyrimidine-2-thione derivatives.235,236 Acylation of N,N -disubstituted thioureas with methyl malonyl chloride followed by base-catalysed cyclization leads in the formation of l,3-disubstituted-2-thiobarbituric acids (Scheme 78).237... 

Another characteristic property of the products of /3-eliminative cleavage of pectic compounds is the reaction with thiobarbituric acid after previous cleavage with periodate, giving rise to red condensation products having229 an absorption maximum at 547-550 nm. Both properties are used for the identification of /3-eliminative cleavage of pectic substances. 

Exposure to periodate yields 3-formylpyruvic acid, which reacts with thiobarbituric acid, giving rise to red condensation products having an absorption maximum at 545-550 nm. Certain workers have used the thiobarbituric acid test without previous oxidation of the unsaturated oligo-D-galactosiduronates with periodic acid.3-29,239,260 Even here, the products of reaction with thiobarbituric acid have an absorption maximum at 550 nm. 

Other indices measure a secondary stage of oxidation, such as the anisidine value (ANV), pointing to formation of carbonyl compounds, capable of undergoing condensation reactions with p-anisidine, and the thiobarbituric acid reactive substance (TBARS) pointing to the presence of malondialdehyde (MDA) in particular. In biological systems, TBARS is of widespread use as a measure for the extent of oxidation damage. Another test for stability of oils to oxidation is based on the development of acidity as secondary product, for example, standards using the Rancimat equipment or a similar setup. 

Sorbic Acid and Sorbates. In addition to the correction of the volatile acidity for sorbic acid already mentioned, both sorbic acid and sorbates must be determined directly. The colorimetric procedure of Jaulmes et al. (10) is appropriate oxidation of sorbic acid to malonic dialdehyde and a red color developed by reaction with 2-thiobarbituric acid (4). 

A promising new method for the preparation of thiobarbituric acids (112) involving the reaction of carbon suboxide with various arylthio-ureas was reported by Baranova et al.2il... 

Kosugi, H. and Kikugawa, K. 1986. Reaction of thiobarbituric acid with saturated aldehydes. Lipids 21 537-542. 

Kosugi, H., Kato, T., and Kikugawa, K. 1987. Formation of yellow, orange, and red pigments in the reaction of alk-2-enals with 2-thiobarbituric acid. Anal. Biochem. 165 456-464. 

Witz, G., Lawrie, N.J., Zaccaria, A., Ferran, H.E. Jr., and Goldstein, B.D. 1986. The reaction of 2-thiobarbituric acid with biologically active alpha, beta-unsaturated aldehydes. J. Free Radic. Biol. Med. 2 33-39. 

The second enzyme in the sequence studied was KD0-8-phosphate synthase. This enzyme was purified to homogeneity (24). This enzyme catalyzes the condensation of D-arabinose-5-phosphate and PEP to yield KD0-8-phosphate and inorganic phosphate. One can assay this irreversible reaction either by measuring the formation of KD0-8-phosphate or the release of P. (2Jj). The latter is the method of choice, since a number of analogues were found to interfer with the thiobarbituric acid assay. The enzyme has an apparent K for PEP of 6 x 10 M and an apparent K for D-arabinose-5-phospftiate of 2 x 10 M. m... 

It has been known for quite some time that in the OH reaction with DNA in the presence of 02 lesions are formed which give rise to the formation of an intensive pink color (Amax = 532 nm) upon reaction with 2-thiobarbituric acid (TBA) in acid solution (Krushinskaya and Shalnov 1967 Gutteridge 1982 Gutteridge and... 

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