Which amines occur naturally in plants and animal tissues?

Naturally occurring amines are found in a variety of plant and animal tissues, serving diverse biological functions. These compounds include:

• Alkaloids: These nitrogen-containing bases are found primarily in plants, particularly in families such as the poppy (Papaveraceae), nightshades (Solanaceae), and buttercups (Ranunculaceae). Examples include morphine, nicotine, cocaine, atropine, and mescaline. While rare, some alkaloids also occur in animal species, such as poison-dart frogs.12
• Catecholamine Neurotransmitters: These include dopamine, epinephrine, and norepinephrine, which play critical roles in the nervous system.3
• Histamine: A local chemical mediator that occurs in most animal tissues.32
• Choline: A quaternary ammonium compound present in nerve synapses and in both plant and animal cells.2
• Methylamines: These occur in small amounts in some plants.2

Additionally, aliphatic amines are produced naturally through the putrefaction of protein material.2