[Effect of dihydroartemisinin at low concentration on intervention of Plasmodium falciparum 3D7 strain].

Malaria is still the most severe strain of the human malaria parasites, and malaria disease is life-threatening which can result in severe anemia and cerebral malaria, especially in children in tropical Africa. Previous studies have shown that artemisinin and its derivatives could selectively kill erythrocytic stage of malaria and have a greater impact on the ring period. In recent years, there have been new findings of its mechanism continually. However, the concentration of artemisinin and its derivatives used in these studies can reach 50 to 80 times the half-inhibitory concentration in vitro. In this study, the international standard strain 3D7 of Plasmodium falciparum was used to culture in vitro. After half-inhibitory concentration of dihydroartemisinin was treated, the morphological changes of P. falciparum intraerythrocytic stage were observed, and then the 3D7 life cycle and effects of different developmental stages after dosing was explored. The 3D7 strain of P. falciparum was continuously synchronised more than 3 times. And dihydroartemisinin (DHA) at half maximal inhibitory concentration (10 nmol·L⁻¹) was administered for 6 hours after the last synchronization, and 3 life cycles were continuously observed (132 h). The results showed that compared with the parasites untreated by DHA, there was a noticeable delay in the life cycle of at least 36 h, indicating that the growth of 3D7 was significantly inhibited by DHA (<0.001), and the rate of ring formation was significantly reduced (<0.05). The trophozoites were abnormal in shape, such as shrink in size, and the number of merozoites in schizonts was significantly decreased (<0.05). These results suggested that non-killing concentrations of DHA (meaning parasites can be inhibited but not killed) can significantly inhibit the growth of P. falciparum, which may not only affect the ring stage, but also have an impact on other stages of the P. falciparum.