Structure-Activity Relationship (SAR) of Benzodiazepines:
The structure-activity relationship (SAR) describes the connection between the chemical or molecular structure of a substance and its biological activity.
· In the case of benzodiazepines, several key structural elements contribute to their pharmacological activity.
Benzodiazepine Core:
The basic structure of benzodiazepines consists of a fused benzene and diazepine ring, forming a bicyclic structure.
This core is critical for activity.
Substitutions at the 5th and 7th Positions:
The presence of electronegative groups (commonly halogens like Cl or F) at the 7th position on the benzene ring enhances activity.
At the 5th position, the presence of a phenyl ring is crucial for activity.
Substitutions at the 1st and 3rd Positions:
At the 1st position of the diazepine ring, a methyl or ethyl group is usually present.
Substitution at the 3rd position with a nitro group enhances sedative effects, while replacement with an amino group reduces sedative effects and can increase anticonvulsant activity.
Substitutions at the 2nd Position:
Substitution with a ketone at the 2nd position is also critical for biological activity.
