A new series of amodiaquine analogues modified in the basic side chain with in vitro antileishmanial and antiplasmodial activity

The synthesis and the study of new amodiaquine derivatives bearing modified lateral basic chains as new agents with both antimalarial and antileishmanial activities are reported. The compounds were tested in vitro against Leishmania donovani MHOM/ET/67/HU3 and 2 strains of Plasmodium falciparum, 3D7 and K1. All the compounds show complex ionisation profiles. At physiological pH the ionised form(s) are in equilibrium with the uncharged form, while at acid pH all the products exist largely as protonated forms. The antiprotozoal profile indicates that all derivatives are endowed with both antimalarial and antileishmanial activity. Interestingly amodiaquine, together with some synthesised derivatives (11, 12, 15, 27, 34), displayed antileishmanial activity in the low micromolar range, although these compounds were also cytotoxic and have a narrow therapeutic window, most of the synthesised compounds proved to be potent antimalarials, a few of them showing a good activity against the chloroquine resistant K1 strain.