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Clinical pharmacy PharmD program Third level Phytochemistry-1 (PG-504)

other. They have the same molecular formula
C 6H 12O 6, but differ in their structural formula.

 Stereoisomer: They are isomers which have the same structure but differ in

their spatial arrangement, i.e., configurations. Asymmetric (Chiral) carbon allow

the formation of the stereoisomers.

Types of Stereoisomers:

• Optical isomers

• Enantiomers or Antipodes (D and L isomers):

• Epimers

• Anomers

• In optical isomerism, the isomers are optically active

 Optical activity:

The capacity of a compound to rotate the plane of polarized light to the left

or right. Such compounds are said to be optically active.

Direction of rotation Type Symbol Example
Right Dextrorotatory or d (+) (+)-Glucose

Left Laevorotatory or l (-) (-)-Fructose

 Levorotatory (–) substance rotates polarized light to the left [e.g., l-glucose;

(-)-glucose].

 Dextrorotatory (+) substance rotates polarized light to the right [e.g., d-

glucose; (+)-glucose].

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