Microscopy of anti-plasmodial action of ΔFd on Plasmodium falciparum 3D7. (A) Untreated or ΔFd-treated, ring-stage synchronized cultures (parasitaemia 1%) were observed after 48 hr. Untreated culture shows high ring-stage parasitaemia, ΔFd IC50 and IC80 treated cultures show low trophozoite-stage and low ring-stage arrested parasitaemia respectively, (B) Untreated or ΔFd-treated trophozoite-stage synchronized cultures were observed after 24 hr. Untreated culture shows intracellular rings while the ΔFd-treated culture shows anomalously egressed trophozoites. Note the selectivity in action on parasitized cells with no effect on uninfected cells. (C) Untreated or ΔFd-treated schizont stage synchronized cultures were observed at 6–12 hr. While schizonts with the characteristic rosette arrangement of merozoites are intracellular at 6 hr in untreated culture, they have (a) prematurely egressed and (b) lost the rosette arrangement of merozoites in the peptide treated culture (For zoom of the images, see additional file 10, panel A). At 12 hr while the merozoites in control have invaded fresh red cells to form rings, the merozoites of peptide treated cultures have failed to invade and form rings (For quantitative account of decrease in invasion events , see additional file 10, panel C).