Inhibitory effects of 9-anilinoacridines on Plasmodium falciparum gametocytes

Two gametocyte-producing isolates of Plasmodium falciparum, KT1 and KT3, we re cultivated in vitro. On day 11 of cultivation, pure gametocytes containi ng stage II, III and IV were used to test the gametocytocidal activity of 9 -anilinoacridines that had previously demonstrated their activity against t he asexual stage of the parasite. After drug exposure for 48 h, gametocytes were maintained without drugs for another 2 days before thin films were pr epared for parasite counting. Gametocytocidal activities of 13 analogs of 9 -anilinoacridine were observed with 50% inhibitory concentrations in the ra nge of 0.6 muM to > 100 muM. The most active compound was 1'-CH(2)NMe(2)(-) 9-anilinoacridine. Anilinoacridine derivatives with 3,6-diamino substitutio n had reduced gametocytocidal activity in contrast to their enhancing effec t against the asexual forms. Morphological abnormalities of gametocytes wer e observed following drug exposure.