Structure. Fatty aldehydes belong to the fatty acyls. Their structure consists of a fatty acid where the carboxyl group of the fatty acid has been replaced with an aldehyde group. The hydrocarbon chain of fatty amides may contain multiple double bonds and can be branched or linear, it may further feature oxygen containing substituents.

Function. Simple fatty aldehydes (FAL) and oxidized fatty aldehydes (oxiFAL) are mostly formed by autooxidation of fatty acids and their levels are carefully kept in balance by intracellular redox-homeostasis. In cells which are not equipped to metabolize them, they cause formational and functional changes to lipid membranes and enzymes when they react with other lipids and proteins. As such, particularly oxiFALs, are considered biomarkers for oxidative stress in relation to some diseases.

FALs have long been studied in relation to rancidity in foods, and fatty aldehyde production tends to increase with ageing and may thus affect age-related disorders such as Alzheimer’s, macular degeneration, or hearing loss. Further, plants emit short-chain fatty aldehydes in response to wounding as they are toxic to most fungi and insects.