What are metabolites

“Any organic or inorganic substance which is produced during metabolic pathways with the help of enzymes or catalyst is called metabolite”

In simple words, metabolites are products of metabolism occurring in living organisms. Metabolism can be

  • Catabolism
  • Anabolism

Metabolites are those intermediate or end products that are produced after biochemical reactions catalyzed by enzymes within the cells. These reactions are collectively termed as Metabolism. Through these reactions, living organisms produce energy to perform their functions. These are required for several functions such as growth, reproduction, homeostasis, and detoxification, etc.

In this article, I will also discuss drug metabolites and their role.

How do metabolites work:

Biochemical pathways occurring in the body are mediated by enzymes and catalysts.

The electron transport chain pathway in mitochondria of a cell is regulated by many enzymes and co-factors.

Metabolites work either by stimulating or inhibiting the enzyme activity of a particular chemical reaction in living organisms.

What do metabolites do:

Metabolites perform several functions

  • Metabolites act as cofactors for enzymes
  • During metabolic pathways, these act as mediators. i.e, signaling
  • Metabolites are very important organic molecules which are responsible for structure building of living species
  • Provide energy to perform vital functions

Metabolites can inhibit or stimulate any enzyme which is taking part in the biochemical metabolic pathways.

Types of Metabolites:

There are two types of metabolites

  • primacy metabolites
  • secondary metabolites

Primary Metabolites

Primary metabolites are called central Metabolites and these are produced within the cell during the growth phase.

They have very specified actions in metabolic pathways.

Primary metabolites are majorly responsible for these functions within a living organism

  • Growth
  • Development
  • Reproduction

Examples of primary metabolites include

  • Amino acids
  • Nucleic acids
  • Vitamins
  • Alcohol

Secondary Metabolites

Secondary metabolites do not have a very defined role. These are not essential parts of metabolic pathways.

Secondary metabolites are produced in plants fungi and microbes. These are not mainly responsible for growth and development. These are very useful in our ecosystem.

For instance, secondary metabolites have great role medicine

An example of a secondary metabolite that is derived from plants is atropine. It is used in the pharmaceutical industry and has a great clinical impact on human health.

Difference between primary and secondary metabolites

Microbial Metabolites

There are hundreds of metabolites that are produced by microorganisms. Industrial microbiology, pharmaceutical industry, and food industry are using these microbial metabolites to produce different products which are helpful for humans. The cosmetic industry is also using different microbial metabolites.

For example, Aspergillus Niger produces citric acid which is widely used in the food industry as well as in the pharmaceutical and cosmetic industries.

Human metabolites

Human metabolites are small molecules like amino acids, organic acids having a molecular weight less than 1500 Da.

Scientists and medical researchers are trying to find out more metabolites produced in our bodies.

During the Arachidonic acid pathway, the main phospholipid precursor is arachidonic acid which follows two pathways (lipoxygenase and oxygenase) to form eicosanoids. Prostaglandin and arachidonic acid have almost similar functional groups.

Other examples of human metabolites in the production of norepinephrine from dietary compounds called tyrosine. Tyrosine is taken up by the cell and through chemical reaction mediated by different enzymes norepinephrine and dopamine is produced.

Similarly, steroidal hormones are synthesized from cholesterol in our bodies through different chemical pathways. The Change in the structure of cholesterol gives different functionality to the metabolites.

Metabolites in blood

There are thousands of metabolites circulating in the blood. The presence of metabolites in the blood can provide very important information regarding health and disease of a particular person, it is called a metabolic signature.

Metabolites in urine

Urine contains many metabolites of drugs and food and other chemicals. Urine metabolites are majorly examined for forensic analysis.

What are drug metabolites

Pro-drugs are converted into its metabolites to produce pharmacological actions. The liver is the major place where drug metabolism occurs. Some drug metabolites are more active than their parent compound while some drug metabolites are less active than original moiety. Metabolites of the drug can stay longer in the body than its original drug. In the laboratory, we can analyze and identify parent drug metabolites in drug abusers for forensic analysis.

Drug metabolism has three phases.

Phase 1 ( CYP 450 enzymes)

Phase 2 ( Conjugation)

Phase 3 ( excretion)

Examples of drug metabolites


 Benzoylecgonine is one the metabolite of cocaine which stays longer in the body than cocaine. The Presence of benzoylecgonine in the body indicates that a person cocaine addict.


In chain smokers, a urine test for nicotine is performed to check either that person is a tobacco user or not. Cotinine is a metabolite of nicotine that stays in the body longer than nicotine. If cotinine is present in urine it means that person is a tobacco user.