Glossary entry

Nitrogenous substances, usually of a basic character (hence the name). They occur in 10-20 percent of taller plants in the Papaveraceae, Fabaceae, Ranunculaceae and Solanaceae family. They form the most numerous group of secondary metabolites of plants (over 7000). The majority of them is virulent (highly poisonous), they were often used in poisoning. Today, they are mostly used in drugs or valuable phramaceuticals. Their biochemical function has not been made clear yet, they probably help plants get rid of pests. They form from amino acids, which was proved with the help of radioactive isotopes. Although almost all alcaloids contain cyclic nitrogenous system, they do not form as unified group as for example steroids do.