A review of dihydroartemisinin as another gift from traditional Chinese medicine not only for malaria control but also for schistosomiasis control.
Artemisinin, also known as qinghaosu, is a sesquiterpene lactone endoperoxide extracted from the plant Artemisia annua L, an herb employed in traditional Chinese medicine. Artemisinin and its two main derivatives artemether and artesunate have been shown to be effective against both malaria and schistosomiasis, and therefore, they were described by Liu et al (Parasitol Res 110:2071-2074, 2012b) as the gifts from traditional Chinese medicine not only for malaria control but also for schistosomiasis control. However, another artemisinin derivative dihydroartemisinin (DHA) cannot be neglected. Dihydroartemisinin, a derivative of artemisinin with the C-10 lactone group replaced by hemiacetal and the active metabolite of all artemisinin compounds, was firstly identified as an antimalarial agent, and the dihydroartemisinin-piperaquine combination has been recommended as a first-line treatment of uncomplicated Plasmodium falciparum malaria by the WHO. It has been recently found that administration of dihydroartemisinin at a single dose of 300 mg/kg 2 h or 3, 5, 7, 10, 14, 18, 21, 28, or 35 days post-infection reduces total worm burdens by 1.1-64.8% and female worm burden reductions by 11.9-90.5%, and the in vivo activity of dihydroartemisinin against S. japonicum is enhanced by the use of multiple doses. However, a combination of praziquantel and dihydroartemisinin appears no more effective against S. japonicum schistosomulum than treatment with dihydroartemisinin alone. In mice experimentally infected with S. mansoni, administration with dihydroartemisinin at a single dose of 300 mg/kg on days 1, 7, 14, 21, 28, 35, 42, 49, or 56 post-infection results in total worm burden reductions of 13.8-82.1% and female worm burden reductions of 13-82.8%, and a clear-cut dose-response relationship of dihydroartemisinin against the schistosomula and adult worms of S. mansoni is observed. In addition, dihydroartemisinin was found to cause damages to the reproductive system of female S. mansoni worms, reduce the oviposition of survival worms, and inhibit the formation of granulomas around tissue-trapped eggs. More interestingly, no reduced sensitivity to dihydroartemisinin is detected in praziquantel non-susceptible S. japonicum, which provides a new option for the treatment of S. japonicum and S. mansoni infections, notably in endemic foci with praziquantel resistance or insensitivity detected. It is therefore considered that dihydroartemisinin is another gift from the traditional Chinese medicine not only for malaria control but also for schistosomiasis control.