Primary and Secondary Metabolites

Introduction to Primary and Secondary Metabolites 

The plants produces chemical substances by using solar energy, water and CO2 by the process of photosynthesis hence called as biosynthetic laboratory that manufacturers both primary and secondary metabolites.

                  The primary metabolites are carbohydrates, amino acid, fatty acids, used by plants for growth; these metabolites are essential for plants development.

                 Secondary metabolites are derived from primary metabolites, these are non-essential for plants but represents chemical adaptations like protection from animals and microorganisms or to attract insects for pollination, etc.

These are waste or secretory products of plant metabolism but having economical and Pharmaceutical importance; example volatile oil, flavonoids etc.

Difference between primary and secondary metabolites is given below;

Primary metabolites

• They are widely distributed in nature and in all organisms,
• They are typically produced continuously during growth phase as a result of energy metabolism,
• They are directly involved in growth, development and reproduction in plants,
• They are non expensive and obtain easily. examples: starch from potato,
• Present in large quantity ,
• Do not show any pharmacological action but utilised as food by animals.
• Usually not complex,
• Examples, starch, cellulose, sugar, amino acid.

Secondary metabolites

• They are limited distributed in plants and can be found in some parts of plants or obtained from primary metabolites or derived from primary metabolites,
• They are not used by plants for growth and development but used as protective defensive are offensive chemicals against microorganisms or herbivorous organisms,
• More complex compound than primary metabolites,
• Present in small quantities than primary metabolites
• They show therapeutic action on human being,
• They are expensive to produce because of lower production of primary metabolites,

Examples of secondary metabolites with their definitions:-

1. Alkaloids
   
        The term alkaloid is derived from the word alkali like. These are the Organic products of natural or synthetic origin, which are basic in nature and contain one or more nitrogen atoms which are heterocyclic in nature and causes specific therapeutic action on human or animal body.
2. Glycosides
   
           These are complex organic molecules which are in conjugation with sugar moieties, mostly monosaccharide from plants or animal sources which on enzymatic or acid hydrolysis gives one or more sugar moieties along with non sugar moiety called as glycoside.
3. Flavonoids
   
       The term derived from the word flavus means yellow the natural colour of flavonoids. These are polyphenols consists of c6c3c6 compounds (15carbon skeleton) in which C6 is benzene ring and the variation in the state of oxidation of the connecting C3 moiety determined the properties of compounds.
4. Tannins
   
         The polyphenolic non nitrogenous substance of higher molecular weight. Used as antiseptic treatment of diarrhoea and also used in leather industries.
5. Volatile oil
   
         Volatile oils are odorous volatile principles of plant and animal source evaporate when exposed to air and ordinary temperature and hence known as volatile or Etheral or Essential oil. These are chemically derived from terpenes (mono and sesqui terpenes) and their oxygenated derivatives.
6. Resins
   
        These are solid or semisolid amorphous products derived from natural living sources, mostly from the plant origin and are nothing but oxidative products of terpenes.