06 Biomolecules - part 07 - Secondary metabolites

 


06 Biomolecules - part 07 - Secondary metabolites


Secondary metabolites (SMs) : 

  • Secondary metabolisms are small organic molecules produced by organisms that are not essential for their growth, development and reproductions.
  • Several types of bacteria, fungi and plants produce secondary metabolism.
  • Secondary metabolites can be classified on the basis of -
  1. chemical structure (e.g. SMs containing rings, sugar)
  2. composition (with or without nitrogen)
  3. their solubility in various solvents, or 
  4. the pathway by which they are synthesized (e.g.phenylpropanoid produces tannins). 
  • A simple way of classifying secondary metabolites includes three main groups such as,
1. Terpenes : 
  • Made from mevalonic acid that is composed mainly of carbon and hydrogen
2. Phenolics : 
  • Made from simple sugars containing benzene rings, hydrogen and oxygen.
3. Nitrogen-containg compounds :
  • Extremely diverse class may also contain sulphur.
Economic importance - Secondary metabolites :
  1. Secondary metabolites from natural sources have made a significant contribution for millennia. 
  2. In modern medicine, drugs developed from secondary metabolites have been used to treat infectious diseases, cancer, hypertension and inflammation.
  3. Morphine was the first alkaloid isolated from plant Papaver somniferum. It is used as pain reliever and cough suppressant.
  4. SMs like alkaloids nicotine and cocaine and the terpenes cannabinol are widely used for recreation and stimulation.
  5. Flavours of secondary metabolites improve our food preference.
  6. Characteristic flavours and aroma of cabbage and its relatives are caused by nitrogen and sulphur-containing chemicals, glucosinolates, protect these plants from many pests.
  7. Tannins are added to wines and chocolate for improving astringency.
  8. Since most of secondary metabolites are having antibiotic properties, they are also used as food preservatives.

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