5. Primary vs Secondary Metabolites

Examples of secondary metabolites


  • Pigments are compounds of various colors that are produced by various organisms for various purposes.
  • These are secondary metabolites and are produced by various organisms like plants and bacteria.
  • Plant pigments like chlorophyll are essential for processes like photosynthesis, whereas bacterial pigments can be extracted to be used in industries as dyes.
  • Pigments are mostly non-toxic and might even have medicinal importance to be used as antioxidants and additives.
  • Bacterial pigments produced for industrial purposes by microbial fermentation has several advantages such as cheaper production, easier extraction, higher yields through strain improvement, no lack of raw materials, and no seasonal.
  • Biopigments produced from microorganisms are preferred over those from plants because of their stability and availability for cultivation throughout the year.
  • Examples of these pigments include chlorophyll, astaxanthin, zeaxanthin, indigoidine, rhodopsin, etc.


  • Flavonoids are secondary metabolites in plants that are found in all fruits and vegetables.
  • Flavonoids are phytonutrients, meaning plant chemical, that also provides some coloration to many plants and animals.
  • These are the largest groups of phytonutrients found in plants with more than 6000 types known.
  • These compounds have important antioxidants with anti-inflammatory and immune system benefits.
  • They also have antimicrobials, photoreceptors, visual attractors, feeding repellants, and for light screening functions.
  • Flavonoids are known to control the development of individual organs and the whole-plant; and, hence, contribute to stress-induced morphogenic responses of plants.
  • Flavonoids may play critical roles as signaling molecules in mammals, through their ability to interact with a wide range of protein kinases.
  • Some examples of flavonoids found in various vascular plants include Apigenin, Luteolin, Hesperetin, Genistein, etc.

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