Alkaloider

Alkaloider, known in English as alkaloids, are a diverse class of nitrogen-containing organic compounds predominantly produced by plants. They are typically basic and often form salts with acids, which aids their storage in plant tissues and their solubility in animals. Most alkaloids are secondary metabolites that serve ecological roles such as defense against herbivores, pathogens, or competition. Many alkaloids are pharmacologically active in humans and other animals, ranging from analgesic and stimulant effects to hallucinogenic and toxic actions.

Chemically, alkaloids are usually heterocycles containing at least one nitrogen atom, and they are commonly derived from amino acids such as tryptophan, tyrosine, ornithine, lysine, or histidine. They are classified as true alkaloids (nitrogen in a heterocycle), protoalkaloids (nitrogen not in the ring), or pseudoalkaloids (nitrogen present but not derived directly from amino acids). They occur widely in plants, notably in the families Solanaceae, Rubiaceae, and Papaveraceae, and are also produced by some fungi and bacteria.

Prominent examples include morphine and codeine, quinine, atropine, caffeine, nicotine, cocaine, and vincristine. These compounds have had lasting impact on medicine and pharmacology, providing analgesia, antimalarial activity, antimuscarinic effects, or roles in cancer therapy as chemotherapy agents. Because of their potent biological activity and potential toxicity, alkaloids are heavily studied and regulated.