Epimer in stereochemistry specifies one of a pair of stereoisomers.  At stereogenic centre, two isomers present in the molecules differ, while the rest remains identical. A molecule may contain numerous stereocenters leading to several stereocenters.


Stereoisomers are isomeric molecules that posses same constitution and molecular formula, but they vary in three-dimensional orientations of their atoms in the space.

Below stereoisomers illustrates the D and L configurations of glucose. Here glucose are referred on the basis of last chiral carbon atom.

Epimers Example

Glucose involves the formation of glycogen, starch, glucose, oligosaccharides and polysaccharides. Due to the presence of carbon in glucose molecule it may exhibit stereoisomerism, that is enantiomers and diastereomers.


Optical isomers or Enantiomers are 2 isomers that are relevant to each other by reflection. They are non – super imposable. They are comprised of same physical properties except in a way they interact with several optical isomers of other compounds. Hence, different optical isomers may have variant biological effects.


Diastereomers are stereoisomers that are not mirror images of each other that they are not linked with reflection operation unlike of enantiomers. They possess the same physical properties. One of the example include meso compounds. The below structure is mesotartaric acid.


Below example illustrates, formation of enantiomeric pair, where mesotartaric acid forms diastereomeric pair with dextro tartaric acids and  levo.

  1. Dextrotartaric acid

Epimers - Dextrotartaric acid

  1. Levotartaric Acid

Epimers - Levotartaric Acid

Epirubicin and Doxorubicin are epimers that are used in drugs.

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