Synthesis and Antiplasmodial Activity of Aminoalkylamino-Substituted Neocryptolepine Derivatives

A series of chloro- and aminoalkylamino-substituted neocryptolepine (5-methyl-5H-indolo[2,3-b]quinoline) derivatives were synthesized and evaluated as antiplasmodial agents. The evaluation also included cytotoxicity (MRC5 cells), inhibition of β-hematin formation, and DNA interactions (DNA−methyl green assay). Introduction of aminoalkylamino chains increased the antiplasmodial activity of the neocryptolepine core substantially. The most efficient compounds showed antiplasmodial activities in the nanomolar range. N1,N1-Diethyl-N4-(5-methyl-5H-indolo[2,3-b]quinolin-8-yl)pentane-1,4-diamine 11c showed an IC50 of 0.01 μM and a selectivity index of 1800.