Evaluation of PTA-derived ruthenium(II) and iridium(III) quinoline complexes against chloroquine-sensitive and resistant strains of the Plasmodium falciparum malaria parasite.

Cationic 1,3,5‑triaza‑phosphaadamantane (PTA) quinoline ruthenium(II) and iridium(III) complexes were successfully synthesized and characterized using standard spectroscopic and analytical techniques. The complexes were evaluated for their in vitro antiplasmodial activities against the chloroquine-sensitive (CQS) NF54 and chloroquine-resistant (CQR) K1 strains of the Plasmodium falciparum species of the malaria parasite and were found to exhibit good activities in the sensitive strain but moderate activities in the resistant strain, suggesting a resistance mechanism similar to chloroquine (CQ). Selected samples were screened for their ability to inhibit synthetic haemozoin formation and were found to be inhibitors with similar activity to CQ. The complexes also exhibit moderate to low cytotoxicity when evaluated against the Chinese Hamster Ovarian (CHO) cell-line in vitro, suggesting selectivity towards the malaria parasite rather than mammalian cells.