Malondialdehyde (MDA), can be generated by oxidizing agents that alters lipid structure, creating lipid peroxides. MDA can be measured as Thiobarbituric Acid Reactive Substances (TBARS).
This method, is convenient to determine the relative lipid peroxide content of samples, including plasma, serum, cell culture supernatants and urine samples.

Multi-unsaturated lipids, are most likely to form peroxides, and so they are the most reactive lipids in the TBARs assay.
TBARs assay is commonly used to compare one set of samples to another.
Lipid oxidation is reported to increase with age and correlates with some clinical features of cardiovascular disease, ischemia/reperfusion and cerebrovascular disorders among others.
 
Lipid peroxidation is a well-defined mechanism of cellular damage. Lipid peroxides are unstable indicators of oxidative stress in cells. They decompose to form more reactive compounds such as Malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), natural biproducts of lipid peroxidation. In vitro, a wide array of pro-oxidant agents can modificate lipids by oxidation and, in vivo, it occurs during aging and in certain disease conditions.

Nowadays, one of the most widely accepted assays for oxidative damage is the measurement of the end products of lipid peroxidation. Specifically, the most generally used test, in the appreciation of the role of oxidative stress in disease, is the MDA assay. During the radical induced decomposition of polyunsaturated fatty acids, MDA is one of the several products. Most often, MDA assay uses its reactivity at high temperature and low pH, towards thiobarbituric acid. Although, this reaction is very sensitive, its specificity, is still a matter of debate. Furthermore, it persit even with the improvement of pre-analytical (sampling, preservatives) and analytical stages (fluorescence, HPLC).  At present, the concept of “thiobarbituric acid reactive substances” (TBARS) have merged and progressively replaced the initial malondialdehyde assay.

The Thiobarbituric Acid Reactive Substances (TBARS) Assay Kit is a tool for the direct quantitative measurement of MDA in biological samples. The samples containing MDA or the MDA standards react with TBA. After incubation, the user can read samples and standards, both spectrophotometrically or fluorometrically. Finally, the user can calculate the concentration of MDA in the samples by comparing with the MDA standard curve.