Malondialdehyde

Malondialdehyd.svg

Malondialdehyde (MDA) is a highly reactive organic compound that is a marker for oxidative stress. It is one of the many reactive electrophile species that cause toxic stress in cells and form covalent protein adducts, known as advanced lipoxidation end-products (ALEs). MDA is a byproduct of lipid peroxidation, which occurs when reactive oxygen species (ROS) attack polyunsaturated fatty acids in cell membranes.

Biochemistry

Malondialdehyde is formed through the peroxidation of polyunsaturated fatty acids, such as arachidonic acid and linoleic acid. The process of lipid peroxidation involves the abstraction of a hydrogen atom from a methylene group in the fatty acid chain, leading to the formation of a lipid radical. This radical can react with molecular oxygen to form a lipid peroxyl radical, which can further propagate the chain reaction of lipid peroxidation.

Measurement

The concentration of malondialdehyde in biological samples is commonly measured as an indicator of oxidative stress. One of the most widely used methods for measuring MDA is the thiobarbituric acid reactive substances (TBARS) assay. In this assay, MDA reacts with thiobarbituric acid (TBA) to form a pink chromogen that can be quantified spectrophotometrically.

Clinical Significance

Elevated levels of malondialdehyde have been associated with various diseases and conditions characterized by oxidative stress, including cardiovascular disease, diabetes mellitus, neurodegenerative diseases, and cancer. Monitoring MDA levels can provide valuable information about the extent of oxidative damage and the effectiveness of antioxidant therapies.

Pathophysiology

Malondialdehyde can form adducts with DNA and proteins, leading to the formation of mutagenic and cytotoxic compounds. These adducts can interfere with normal cellular functions and contribute to the pathogenesis of various diseases. For example, MDA-DNA adducts can cause mutations that may lead to cancer, while MDA-protein adducts can impair enzyme activity and disrupt cellular signaling pathways.

See Also

• Oxidative stress
• Lipid peroxidation
• Reactive oxygen species
• Antioxidant
• Thiobarbituric acid reactive substances assay