Alkaloids

Alkaloids are a class of naturally occurring organic compounds that contain at least one nitrogen atom. Most alkaloids are produced by plants and are often heterocyclic and basic, with structures that resemble amines. They typically form salts with acids and can have strong physiological effects at relatively low doses.

These compounds are widespread in the plant kingdom and are especially abundant in families such as Solanaceae, Papaveraceae, and Rubiaceae, though they also occur in fungi and some bacteria. They are usually secondary metabolites, synthesized from amino acids such as ornithine, lysine, tyrosine, tryptophan, or phenylalanine, and are thought to serve defensive roles against herbivores and pathogens.

Alkaloids display great structural diversity and are commonly categorized by their ring systems and biosynthetic origins. Notable examples include morphine and codeine, quinine, nicotine, caffeine, atropine and scopolamine, strychnine, and ephedrine. Many alkaloids are bitter and biologically active, often affecting the nervous system or other physiological targets.

Pharmacology and applications: Many alkaloids have significant pharmacological activity and have been used as medicines, stimulants, or poisons. Examples include analgesics like morphine, antimalarials like quinine, anticholinergics like atropine, and stimulants like caffeine and nicotine. Because of their potency, proper dosing and medical supervision are important, and some alkaloids can interact with other drugs.

Analysis and regulation: Alkaloids are typically isolated from plant material by acid-base extraction and purified by chromatography. Regulation varies by country; several alkaloids are controlled substances due to misuse potential. Owing to their biological activity, alkaloids remain a major focus of pharmacological research and natural product chemistry.