Alkaloids

Abstract

Alkaloids are a diverse group of organic bases containing secondary, tertiary, or cyclic amines. Some 5500 alkaloids are known, comprising the largest single class of secondary plant substances. There is no one definition of the term alkaloid, which is completely satisfactory, but alkaloids generally include “those basic substances which contain one or more nitrogen atoms, usually in combination as part of a cyclic system.” (1) Chemically, alkaloids are a very heterogeneous group, ranging from simple compounds like coniine, the major alkaloid of hemlock, Conium maculatum, to the pentacyclic structure of strychnine, the toxin of the Strychnos bark. Many alkaloids are terpenoid in nature, and some (e.g., solanine, the steroidal alkaloid of the potato, Solanum tuberosum) steroidal. Others are mainly aromatic compounds (e.g., colchicine).