Block 5 (Test 1) Flashcards
what is a bioisostere?
a substituent or functional group with similar chemical/physical properties and which produces broadly similar biological properties
List examples of classical monovalent bioisosteres
CH3 OH NH2 S
list examples of classical divalent bioisosteres
R-O-R, R-NH-R, R-CH2-R
List examples of classical trivalent bioisosteres
R-N=R, R-CH=R
List examples of classical tetravalent bioisosteres
R=C=R, R=N=R, R=P=R
what are non-classical bioisosteres?
they do not have the same number of atoms and do not fit steric or electronic rules of classical isosteres, but they have similar biological activity
boronic acid is a bioisostere of _______. what is the result of using this bioisostere?
carboxylic acid boronic acid forms a covalent bond instead of a hydrogen bond (how COOH works), thus making it a suicide inhibitor
what is a prodrug?
an inactive compound that is converted (either chemically or enzymatically) to the active form (once in the body)
what are the two main considerations when making a prodrug?
effective conversion to active drug in the blood stream the prodrug “shield” group is not toxic when released
describe the function of ester prodrugs
carboxylic acids are excellent HBA and HBD, but they ionize too easily which can be a problem in crossing membranes a prodrug is used to protect the acid function by making it an ester. the less polar ester can cross the membrane and be hydrolyzed to the acid by an esterase enzyme
how do prodrugs aid in circumventing metabolism?
they are often designed to be slowly converted into the active metabolite in order to prolong plasma levels
give an example of how prodrugs mask toxicity
ex. salicylic acid is known to cause GI bleeding due to its phenolic group. by making it a prodrug (masking the phenol), the active drug is only exposed by esterases once it enters the bloodstream
what is the most common activation pathway of a prodrug?
hydrolysis with esterase
the major objectives of prodrugs are
improved bioavailability improved aqueous solubility improved passive intestinal absorption
NMR stands for
nuclear magnetic resonance