In vitro activity of artemisinin alone and in combination with retinol against Plasmodium falciparum.

Increasing resistance of Plasmodium falciparum to antimalarial drugs is an important public health problem, demanding novel therapeutic approaches. This study had the objective of assessing the in vitro activity of artemisinin and its combination with retinol in fresh isolates of P. falciparum in an area with a high proportion of multidrug-resistant strains. The tests were based on the inhibition of schizont maturation. In 45 successfully tested isolates, the mean effective concentrations (ECs) of artemisinin were 10.29 nM for the EC-50 and 34.86 nM for the EC-90. The EC50 and EC90 for artemisinin in the artemisinin-retinol mixture were 2.71 nM and 13.37 nM, respectively. The combination showed synergistic activity. Retinol appears to be a promising partner for the antimalarial therapy with artemisinins.