FIG 5.

Antiplasmodial activity of 10-amino artemisinins compared to their cross-stage activity and gametocyte stage specificity. A scatter plot of the IC₅₀ data for the compounds against asexual, early gametocyte (EG), and late gametocyte (LG) stages is shown. The results for the reference compounds (artemisinin, DHA, artesunate, and artemether) are indicated in gray scale, and those for the 10-amino artemisinins are indicated in color. The 10-sulfamide showed a consistent loss of activity from the asexual to the late gametocyte stages, like that observed for the reference compounds, whereas artemisone showed early gametocyte stage specificity with a loss of activity toward late gametocyte stages. Both artemiside and 10-phenylurea showed late gametocyte stage-specific 10-amino groups. Data are means of the IC₅₀s for the oxidant compounds for each life cycle stage. P values were determined by an unpaired t test. *, P = 0.03; ***, P = 0.0002.