Prof.Dr. Meral Tunçbilek
ISOMERISM IN DRUG
ACTIVITY
Diastereomers are stereoisomers that are not related as object and mirror image and are not enantiomers. Unlike enatiomers which are mirror images of each other and non-sumperimposable, diastereomers are not mirror images of each other and non-superimposable.
Diastereomers can have different physical properties and reactivity. They have different melting points and boiling points and different densities. They have two or more stereocenters.
Compounds having two different chiral or assymetric carbon atoms are named by using prefix- erythro or
threo.
When two same groups are on the same side of chiral carbon atom in fischer Projection formula then it is ‘ erythrose ‘. When two identical groups are on the opposite side of chiral carbon atom in Fischer Projection formula then it is ‘threose’
Perhaps the best known example of this is tartaric acid, which exists as three stereoisomers (two enantiomers and a meso compound).
Crystals of potassium hydrogen (R,R)-tartrate are often to be found in the bottom of wine bottles.
• In stereochemistry, an epimer is one of a pair
of stereoisomers. The two isomers differ in configuration at only one stereogenic center. All other stereocenters in the molecules are the same in each.
• Doxorubicin and epirubicin are two epimers that are
