A modification of the thiobarbituric acid reaction

Methodology for measuring malonaldehyde as a product of lipid peroxidation in muscle tissues: A review

The purpose of this review is to summarize concerns regarding the formation and quantification of malonaldehyde as a product of lipid peroxidation in muscle tissues. The spectrophotometric thiobarbituric acid (TBA) method is the most frequently used test for malonaldehyde quantification, especially in muscle tissues, as a marker of lipid peroxidation. However, the TBA method has been criticized as lacking specificity and adequate sensitivity towards malonaldehyde. High performance liquid and gas chromatographic methods offer better specificity and sensitivity for malonaldehyde detection. The TBA method, however, may be preferred over the chromatographic method because of its simplicity, especially when a large number of samples need to be analyzed in a short period of time on a daily basis. In addition, the TBA method has been correlated with other objective and subjective methods of measuring lipid peroxidation and its specificity can be improved with the use of a solid phase extraction C(18) cartridge.

Lipid oxidation on foods

This review discusses the basic chemical reactions that affect food flavor quality. Although there are many reactions that can lead to the deterioration of quality in foods, this review focuses on lipid oxidation and how it adversely affects flavor principals. It also presents technological advances for studying the basic mechanism of lipid oxidation, for measuring its intensity, and for retaining food quality. The food commodities that provide the subject matter for this review include vegetable oils, legumes, cereal grains, eggs, beef, lamb, poultry, seafoods, and catfish. The methodologies for assessing food quality form a multidisciplinary approach that includes primarily instrumental analysis by direct gas chromatography, chemical analysis by the TBA test, and sensory analysis by quantitative descriptive determinations. The author hopes that the information presented in this review is applicable to food commodities not discussed.

Characteristics of the thiobarbituric acid reactivity of human urine as a possible consequence of lipid peroxidation

A 532 nm red pigment formed in the thiobarbituric acid (TBA) assay of human urine was characterized after separation of the pigment by high-performance liquid chromatography. The yield of the red pigment was somewhat higher at pH 2 than at pH 5; its development was not inhibited by ethylenediaminetetraacetic acid. The characteristics of the pigment were similar to those of the pigment derived from standard malonaldehyde. The amount of the pigment formed was roughly equal to the content of malonaldehyde derivatives estimated as 1-(2,4-dinitrophenyl)pyrazole. Pigment formation was significantly enhanced by t-butyl hydroperoxide (t-BuOOH) and ferric ions, which may be due to pigment formed from aldehydes other than malonaldehyde; the presence of these aldehydes was confirmed by the formation of the corresponding 2,4-dinitrophenylhydrazones. The amount of pigment produced from 24-h urine samples of 12 healthy subjects was estimated to be 26-95 nmol/kg, and 65-182 nmol/kg in the presence of t-BuOOH. These values are lower than those for urine of rabbit or rat. The TBA reactivity in the absence and presence of t-BuOOH of human urine was not related to age or sex. The TBA reactivity of human urine collected in the afternoon and in the evening was higher than that of urine collected in the morning.

High-performance liquid chromatographic separation of malondialdehyde-thiobarbituric acid adduct in biological materials (plasma and human cells) using a commercially available reagent

The assay of malondialdehyde (MDA) is widely used in clinical chemistry laboratories to investigate lipid peroxidation in oxidative pathologies. In the present work, the thiobarbituric acid (TBA) reaction was carried out on plasma, human erythrocytes and fibroblasts. The reagents used were those of the fluorimetry MDA kit manufactured by Sobioda. We have defined the application of this kit to high-performance liquid chromatography. This adaptation satisfied the criteria of good analytical practice. The detection limit was 2.5 pmol per injection. The retention time of the MDA-TBA2 peak (4.96 +/- 0.07 min) led to excellent resolution of the complex. The within-assay (6-12%) and between-assay (11-12%) precisions were satisfactory. The analytical recovery of MDA after spiking samples of human plasma with tetraethoxypropane standards varied from 70 to 100%. The mean lipoperoxide concentration determined in 32 healthy adults (20-40 years) was 1.04 +/- 0.23 mumol l-1 in plasma. Applied to the erythrocytes of fifteen laboratory workers, the method furnished physiological values of 0.59 +/- 0.21 mumol l-1. Concentrations were significantly higher in chronic renal dialysis patients (4.15 +/- 2.35 mumol l-1. The MDA content of fibroblasts cultured in standard medium was 0.38 +/- 0.04 mumol per g of protein and increased (5.78 +/- 1.38 mumol per g of protein) if the cells were grown in an iron-enriched medium. This accurate high-performance liquid chromatographic method for detection of MDA is the first one which can be applied to plasma, red blood cells and cultured cells. This technique will prevent false positives and should make inter-laboratory comparisons possible.

Blood antioxidant status and erythrocyte lipid peroxidation following distance running

The relationship between prolonged exercise, oxidative stress, and the protective capacity of the antioxidant defense system has been determined. Venous blood samples were removed from seven trained athletes before and up to 120 h after completion of a half-marathon for measurements of blood antioxidants, antioxidant enzymes, and indices of lipid peroxidation. Plasma creatine kinase (CK) activity, an index of muscle damage, increased (P less than 0.05) to a maximum 24 h after the race but this was not accompanied by changes in conjugated dienes and thiobarbituric acid reactive substances (TBARS), which are indices of lipid peroxidation. An increase (P less than 0.05) in plasma cholesterol concentration (4%) immediately after the race was similar to the change in plasma volume (6%). However, transient increases (P less than 0.05) immediately postrace in the plasma concentrations of uric acid (24%), vitamin A (18%), and vitamin C (34%) were only partly accounted for by the fluid shifts. The immediate postrace increases in alpha- and gamma-tocopherol did not attain statistical significance. Erythrocyte antioxidant enzyme activities were unaffected by the exercise but the alpha- and gamma-tocopherol concentrations progressively increased (P less than 0.001 and P less than 0.05, respectively) up to 48 h postrace. Paradoxically, 24 h after the race erythrocyte susceptibility to in vitro peroxidation was markedly elevated (P less than 0.01). This enhanced susceptibility to peroxidation was maintained even at 120 h postrace and did not correspond to changes in the age of the red cell population. A decrease (P less than 0.001) in total erythrocyte glutathione immediately after the half-marathon was mainly due to a reduction in the reduced form (GSH). The results show that when trained athletes run a comparatively short distance sufficient to result in some degree of muscle damage but which is insufficient to cause elevations in plasma indices of lipid peroxidation, significant alterations in erythrocyte antioxidant status do occur.

Alteration of plasma low density lipoprotein from smokers

Thiobarbituric acid reactive substances (TBARS) in 38 low density lipoprotein (LDL) samples from 21 healthy male non-smokers and 17 smokers (greater than 20 cigarettes per day) were measured before and after oxidation. TBARS in the freshly isolated LDL from non-smokers and smokers were similar, however, oxidized LDL samples from smokers developed nearly twofold more TBARS than non-smoker LDL samples. 16 LDLs from 8 smokers and 8 non-smokers were conditioned in redox-metal containing F-10 medium and subsequently added to P 388 D.1 macrophage cultures. LDL dependent cholesteryl ester increase in the P 388 D.1 cells after an 18 h incubation with non-smoker LDL was significantly lower than in the cells incubated with smoker LDL (P less than 0.01). A higher reacylation rate of cholesterol in P 388 D.1 cells incubated with smoker LDL (P less than 0.05) suggests that LDL-cholesterol uptake is significantly higher in P 388 D.1 cells incubated with smoker-LDL than in P 388 D.1 cultures exposed to non-smoker LDL. This finding indicates that smoking might contribute to increased shunting of LDL into macrophages. The vitamin E content of 6 non-smoker LDL samples was significantly higher than that in 6 smoker-LDL samples (P less than 0.01). We conclude that the vitamin E/LDL ratio may differ significantly in heavy smokers and non-smokers.

Malondialdehyde and thiobarbituric acid-reactivity as diagnostic indices of lipid peroxidation and peroxidative tissue injury

Increasing appreciation of the causative role of oxidative injury in many disease states places great importance on the reliable assessment of lipid peroxidation. Malondialdehyde (MDA) is one of several low-molecular-weight end products formed via the decomposition of certain primary and secondary lipid peroxidation products. At low pH and elevated temperature, MDA readily participates in nucleophilic addition reaction with 2-thiobarbituric acid (TBA), generating a red, fluorescent 1:2 MDA:TBA adduct. These facts, along with the availability of facile and sensitive methods to quantify MDA (as the free aldehyde or its TBA derivative), have led to the routine use of MDA determination and, particularly, the "TBA test" to detect and quantify lipid peroxidation in a wide array of sample types. However, MDA itself participates in reactions with molecules other than TBA and is a catabolic substrate. Only certain lipid peroxidation products generate MDA (invariably with low yields), and MDA is neither the sole end product of fatty peroxide formation and decomposition nor a substance generated exclusively through lipid peroxidation. Many factors (e.g., stimulus for and conditions of peroxidation) modulate MDA formation from lipid. Additional factors (e.g., TBA-test reagents and constituents) have profound effects on test response to fatty peroxide-derived MDA. The TBA test is intrinsically nonspecific for MDA; nonlipid-related materials as well as fatty peroxide-derived decomposition products other than MDA are TBA positive. These and other considerations from the extensive literature on MDA. TBA reactivity, and oxidative lipid degradation support the conclusion that MDA determination and the TBA test can offer, at best, a narrow and somewhat empirical window on the complex process of lipid peroxidation. The MDA content and/or TBA reactivity of a system provides no information on the precise structures of the "MDA precursor(s)," their molecular origins, or the amount of each formed. Consequently, neither MDA determination nor TBA-test response can generally be regarded as a diagnostic index of the occurrence/extent of lipid peroxidation, fatty hydroperoxide formation, or oxidative injury to tissue lipid without independent chemical evidence of the analyte being measured and its source. In some cases, MDA/TBA reactivity is an indicator of lipid peroxidation; in other situations, no qualitative or quantitative relationship exists among sample MDA content, TBA reactivity, and fatty peroxide tone. Utilization of MDA analysis and/or the TBA test and interpretation of sample MDA content and TBA test response in studies of lipid peroxidation require caution, discretion, and (especially in biological systems) correlative data from other indices of fatty peroxide formation and decomposition.