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Plant Alkaloids

  1. Karin Fester

Published Online: 15 MAR 2010

DOI: 10.1002/9780470015902.a0001914.pub2



How to Cite

Fester, K. 2010. Plant Alkaloids. eLS. .

Author Information

  1. Leipzig, Germany

Publication History

  1. Published Online: 15 MAR 2010


Alkaloids are traditionally defined as basic (alkali-like), nitrogen-containing organic constituents that occur mainly in plants. The nitrogen in the alkaloid molecule is derived from amino acid metabolism. Since the amino acid skeleton is often largely retained in the alkaloid structure, alkaloids originating from the same amino acid show similar structural features and can be classified according to their biosynthetic origin. The biosynthesis of alkaloids often follows complex pathways and includes stereospecific steps. Alkaloids often have pronounced bioactivities and are therefore thought to play an important role in the interaction of plants with their environment. Alkaloids and extracts of alkaloid-containing plants have been used throughout human history as remedies, poisons and psychoactive drugs.

Key Concepts

  • Alkaloids are a heterogeneous class of secondary metabolites.

  • Alkaloids are defined as basic compounds derived from amino acids, often with heterocyclically bound nitrogen. Pseudoalkaloids are nitrogen-containing natural products that do not arise from an amino acid core and acquire their nitrogen by transamination of a precursor derived from other biosynthetic pathways.

  • Alkaloids are biosynthesized via complex pathways that may comprise 20 or more enzymatic steps.

  • Many alkaloids possess pronounced biological activities, which are often associated with their amine function.

  • Several alkaloids are used medicinally or provide lead structures for novel synthetic drugs.

  • Owing to their bioactivities, alkaloids are often toxic to herbivoures. Nevertheless, they may be exploited by specialized species of herbivoures as defence compounds.

  • Alkaloid-producing tissue cultures provide an alternative for exploiting slow growing or protected plants. Moreover, they can be utilized for biosynthetic studies and for the commercial production of valuable alkaloids.


  • alkaloids;
  • natural products;
  • plant constituents;
  • plant drugs;
  • secondary metabolites