Synthesis and Pharmacological Evaluation of Some Quinoline Derivatives as Potential Antiamnesic Agents

A deficit of cholinergic neurotransmission is considered to be one of the major causes of disturbance in learning and memory. Among the various therapeutic approaches investigated to enhance cholinergic transmission, acetylcholinesterase (AChE) inhibition is presently the most successful method to ameliorate cholinergic deficit. Keeping in view the activity of numerous quinoline derivatives reported as potential cognitive enhancers attempts were made to design and synthesize some 6-aminoquinoline derivatives. The title compounds were synthesized via an intermediate 6-nitroquinoline which was prepared by Skraup synthesis from 4-nitroaniline prepared from acetanilide by its nitration and subsequent hydrolysis. 6-Nitroquinoline after reduction was treated with various aldehydes (veratraldehyde, anisaldehyde, 3-hydroxybenzaldehyde, indole-3-carboxaldehyde etc.) to give the target compounds. Some of the compounds showed a significant memory enhancing activity using elevated plus maze at 5 mg/kg and 10 mg/kg doses. Biochemical studies have shown the compounds to possess unexpectedly good acetylcholinesterase inhibitory activity (max %inhibition 65.27).