Secondary Metabolites

  • Satish C Bhatla


Plants synthesize an enormous array of organic compounds/metabolites, a large number of which are involved in facilitating the basic vital processes, such as growth, cell division, respiration, photosynthesis, reproduction, and storage. These metabolites are known as primary metabolites, while the rest of the compounds do not have any role in primary metabolism. These compounds perform varied functions and are collectively referred as secondary metabolites. At biosynthetic level, both categories of compounds are synthesized from same basic metabolic pathways and share many intermediates (Fig. 33.1). Secondary metabolites are also referred as secondary products, specialized metabolites, or natural products. More than 2,00,000 secondary metabolites have been identified till now. Primary metabolites are generally produced in large concentrations as they are required in vital processes. However, secondary metabolites are mostly produced in small quantities, are structurally diverse, and may have a restricted distribution in specific families, genera, or species. Due to their confined, specific distribution, secondary metabolites can be used as a diagnostic tool in chemotaxonomic studies. For many years, the significance of secondary metabolites was not well understood, and they were believed to be mere metabolic wastes or functionless intermediates or end products of primary metabolism. Later, investigations initiated in the nineteenth century, pioneered by organic chemists, revealed the importance of secondary metabolites in medicines (e.g., discovery of aspirin (acetylsalicylate), as defensive compounds (phytoalexins), role in restricting germination and growth of other plants growing in the vicinity (allelopathy), UV protection, etc. Therefore, these metabolites help in adaptation of plants according to their environment. Some of their major roles are:


Alkaloids Anthocyanins Cardenolides Glucosinolates Glycosides Phenolics Phenylpropanoids Saponins Shikimic acid pathway Tannins Terpenes 

Suggested Further Reading

  1. Kutchan TM, Gershenzon J, Moller BL, Gang DR (2015) Natural products. In: Buchanan BB, Gruissem W, Jones RL (eds) Biochemistry and molecular biology of plants. Wiley Blackwell, London, pp 1132–1206Google Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • Satish C Bhatla
    • 1
  1. 1.Department of BotanyUniversity of DelhiNew DelhiIndia

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