What is a Polyamine?

Polyamines are organic chemical compounds with molecules composed of at least two amino groups. Many types of polyamines are produced naturally in living organisms, including humans, and are involved in some biological processes. Synthetic polyamines also exist and are produced for industrial use. These compounds are composed principally of carbon, nitrogen, and hydrogen and often have a strong odor similar to that of ammonia.

Amino groups, or amines, are organic derivatives of ammonia (NH₃) in which at least one hydrogen atom has been replaced by another atom or group of atoms, called a substituent or side-chain. These substituents are frequently groups of single-bonded carbon and hydrogen atoms called alkyl groups. Other amines have substituents called aromatic hydrocarbons, unusually stable substances such as benzene (C₆H₆) in which each carbon atom is bonded to two other carbon atoms by alternating single and double bonds to form a ring. Every polyamine is made of at least two amino groups, with the properties of each polyamine varying according to its components.

These compounds are produced in all known forms of life. Natural polyamines such as spermidine (C₇H₁₉N₃), putrescine (C₄H₁₂N₂), and cadaverine (C₅H₁₄N₂) are part of the process of cellular metabolism and signaling. The precise role played by natural polyamines in biochemistry is still not fully understood, but it is known that inhibiting polyamine synthesis slows or stops cell growth. In plants, polyamines are among the chemicals that function as plant hormones, which regulate the plant's growth, development, and senescence. Polyamines may also be involved in the process of apoptosis, or programmed cell death.

Large quantities of polyamines are naturally produced by the decay of dead organisms as their amino acids break down, producing putrescine and cadaverine. These substances are very strong-smelling and are the primary source of the foul odor produced by rotting flesh. They are toxic in large doses, though small quantities of them are also produced in the cells of living, healthy organisms.

Many polyamines are also produced synthetically and used for industrial purposes, such as the production of other chemicals in the chemical industry. The polyamine ethylenediamine (C₂H₈N₂) and its derivatives are used for processes including electroplating, photograph development, and the production of polyester and as ingredients in products such as paint, coolant, and animal feed. Mexamethylenediamine (C₆H₁₆N₂) and industrially synthesized putrescine are used to produce nylon polymers, which are important to the textile industry. Mexamethylenediamine is also used to produce some types of polyurethane, another polymer widely used in consumer and industrial goods.