stereochemistry Flashcards
the physicochemical properties of a drug molecule are dependent not only on what functional groups are present in the molecule but also on the spatial arrangement of these groups
stereochemistry
how a particular drug molecule interacts with its biologic target is determined by:
its 3-dimensional orientation of the functional group present
if the functional groups w/in a drug molecule are located in the proper 3-D orientation:
then the drug can participate in multiple key interactions with its biologic target
if critical functional group in the drug molecule do not occupy the proper spatial region:
then productive interactions with its biologic target will no be possible
it is important to understand not only w/c functional groups contribute to the pharmacologic activity of a drug, but also the importance of the 3-D nature of these functional groups in predicting :
drug potency & potential side effects
-molecules that contain the same number & kinds of atoms, the same arrangement of bonds, but different 3_D structures
-they only differ in the 3-D arrangement of atoms in space
stereoisomers
2 types of steroisomers
-enantiomers
-diastereoisomers
pairs of molecules for w/c the 3-D arrangement of atoms represents nonsuperimposable mirror images
enantiomers
-represent all of the other steroisomeric compounds that are not enantiomers
-includes compounds that contain double bonds (geometric isomers) & ring systems
-exhibit different physicochemical properties, including but not limited to, melting point, boiling point, solubility, & chromatographic behavior
diastereoisomers
at first, enantiomers were distinguished by their
ability to rotate the plane of polarized light
-rotate the plane of polarized light to the right or in clockwise direction
-indicated by a + sign
dextrorotatory
-rotate the plane of polarized light to the left, or in a counterclockwise direction
-indicated by a - sign
levorotatory
dextrorotatory examples
dextromethorphan
dextroamphetamine
dexlansoprazole
levorotatory examples
levodopa
levothyroxine
levofloxacin
were formerly used to indicate (+) & (-) respectively
D & L
most sugars found in nature are:
dextrorotatory
glyceraldehyde
glucose (dextrose)
most amino acids found in nature are
levorotatory
serine
alanine
comprised of equal amounts (1:1 mixture) of both of the possible drug enantiomers
-indicated by placement of a +&- before the compound
racemic mixture
nisoxetine
talopram
many drugs administered in humans are
racemic mixtures
usually, one enantiomer tends to be
much more active than the other
2 enantiomers present in a racemic mixture may differ in
pharmacological activity
levorphanol (analgesic)
dextrophan (antitussive)
new system of stereochemical nomenclature
Cahn-Ingold-Prelog (CIP) system
r-configutaion
s-configuration
priority sequence proceeds to the right, or in a clockwise direction
R- conformation
priority sequence proceeds to the left, or counterclockwise direction
S- configuration
