Cadaverine is a biogenic amine, a class of organic compounds derived from amino acids. It is perhaps best known for its unpleasant odor, which is strongly associated with the decomposition of animal tissues. This foul-smelling molecule, first identified in 1885, is chemically classified as a diamine, containing two amino groups in its structure.
The Source of the Odor
The characteristic smell of decay is largely attributable to the production of cadaverine and a related compound, putrescine. This process begins after death, when the body’s tissues start to break down in a process called putrefaction. This decomposition is driven by bacteria, which metabolize the body’s abundant proteins. Environmental factors like higher temperatures can accelerate this process, leading to a faster rate of cadaverine production.
These bacteria specifically target amino acids, the building blocks of proteins. Cadaverine is formed directly from the amino acid lysine through a chemical reaction known as decarboxylation. In this reaction, a specific enzyme removes a carboxyl group from the lysine molecule, converting it into cadaverine (1,5-pentanediamine).
A similar process occurs with the amino acid ornithine, which is converted into putrescine (1,4-butanediamine). The combination of these two diamines creates the recognizable odor of decaying organic matter. This process is not limited to animal remains; it occurs in any environment where protein-rich organic matter is decomposing under oxygen-limited conditions. The bacteria responsible for this transformation are widespread in the environment.
Cadaverine in Living Organisms
Contrary to its name and origin, cadaverine is not exclusively a molecule of death. It is produced in small, regulated amounts in many living organisms, including humans. Polyamines like cadaverine are involved in a wide variety of cytoplasmic reactions, including DNA replication and protein synthesis. The molecule can play a role in regulating intracellular pH and stabilizing cell membranes.
Its presence extends to the plant kingdom, where it contributes to growth, development, and responses to environmental stress. Endogenous cadaverine has been detected in various plant species, including wheat, rice, and legumes, though its concentration can vary significantly depending on the species and developmental stage. In some plants, cadaverine is involved in defense mechanisms against insects and helps mediate responses to stresses like high salinity or the presence of heavy metals.
In some bacteria, cadaverine is a component of the cell wall, contributing to the structural integrity of the bacterium. This demonstrates that while its association with decay is strong, cadaverine also serves constructive purposes in the machinery of life.
Cadaverine in Food and Diet
Cadaverine is not just found in decomposing matter; it is also present in a variety of foods that people consume. Its presence can be an indicator of spoilage, particularly in protein-rich foods like meat and fish, where high levels suggest bacterial contamination.
However, cadaverine can also be formed intentionally during certain food production processes, especially fermentation. Many fermented products, including aged cheeses, cured sausages, and fermented soy products, can contain cadaverine as a byproduct of microbial activity. The levels can vary greatly depending on the specific microbes used, the fermentation conditions, and the length of aging.
For instance, studies have detected significant concentrations of putrescine and cadaverine in fermented meat and fish. Fermented foods like sauerkraut and certain ripened cheeses can also contain notable amounts of these biogenic amines. While its presence in spoiled food is a clear warning sign, its occurrence in these fermented products is a natural outcome of the desired microbial transformations that create unique flavors and textures.
Health and Safety Considerations
In the small amounts produced by the body or found in properly fermented foods, cadaverine generally has low toxicity. However, high concentrations, especially those found in spoiled food, are an indicator of poor hygiene and unsuitability for consumption. Although not highly toxic on its own, it can become a concern when ingested in larger quantities.
One of the primary health considerations is that cadaverine can potentiate the toxic effects of other biogenic amines, such as histamine. It can inhibit the enzymes in the body that would normally break down histamine, leading to an amplified effect. This interaction can contribute to symptoms often associated with food poisoning, such as headaches and changes in blood pressure.
Under certain conditions, biogenic amines like cadaverine can be precursors to the formation of nitrosamines, which are compounds considered to be carcinogenic. While tolerable levels for cadaverine in different foods have been proposed, these can vary widely. Individuals with a reduced capacity to detoxify biogenic amines, due to genetic factors or certain medications, may be at a greater risk from consuming foods with high levels of these compounds.