Synthesis and 5-HT3 affinity of new 3-substituted indoles at central nervous system

A series of 3-imino and 3-aminomethyl-N-methylindoles, in which the amine substituents were 3-quinuclidyl and 1-adamantyl groups, were synthesized and their in vitro affinity towards 5-HT3 central receptors evaluated. Of the nine compounds tested, three caused displacement of 3H-BRL 43694 binding to 5-HT3. 2-Chloro-3-(3-quinuclidylimino)-1-methylindole, 4, was the most potent compound with an IC50 = 5.15 10(-8) M. Moreover, the monoamine oxidase inhibition activity was tested and three compounds were shown to be MAO inhibitors, their IC50 was in the range of that of (-)-Deprenyl. Again, 4 was the most potent compound. Structure-activity relationships within the series are briefly discussed.