Pharmacokinetics and antimalarial activities of reduction-responsive releasing dihydroartemisinin prodrug self-assembled nanoparticles in rodents

Artemisinin and its derivates (ARTs) exert antimalarial effect by virtue of unique endoperoxide bridge, which is generally considered to generate oxygen free radicals and then form carbon-centered free radicals to damage parasites. The known high level of glutathione (GSH) in parasites plays a key role in maintaining redox balance to protect parasites from oxidative stress damage, which may be a risk factor for the failure of ARTs-based combination therapy and drug resistance. Nevertheless, the highly reducing environment in cytoplasm of malaria parasites provides an available trigger for intracellular nanoparticle disassembly to responsively release drug. In this study, a reduction-responsive releasing dihydroartemisinin (DHA) prodrug (C14-SS-DHA) was synthesized by conjugating DHA and tetradecylamine (C14-NH2) with disulfide bond (-SS-) as a linker. As a control, a DHA carbon-carbon bond (-CC-) prodrug (C14-CC-DHA) was synthesized using succinic anhydride as a -CC- linker. To note, DHA prodrugs were prepared as self-assembled nanoparticles (C14-SS-DHA NPs and C14-CCDHA NPs). The size and zeta potential of C14-SS-DHA NPs were 121 +/- 1.582 nm and -29 +/- 0.635 mV, and those of C14-CC-DHA NPs were 137.5 +/- 0.5132 nm and -41 +/- 0.377 mV, respectively. The C14-SS-DHA NPs can release DHA in a reductive media in vitro. The pharmacokinetics study showed that the area under the curve (AUC(0-t)) of plasma concentration versus time of DHA from C14-SS-DHA NPs was 20737.2 +/- 6028.3 h mu g L-1, which was much higher than that of C14-CC-DHA NPs (6254.5 +/- 2578.8) or DHA solution (857.6 +/- 103.7 h mu g L-1). The pharmacodynamics study presented that the ED90 of C14-SS-DHA NPs was 3.81 +/- 0.35 mu mol/kg, which was lower than that of C14-CC-DHA NPs (12.70 +/- 1.63 mu mol/kg)) or DHA solution (17.67 +/- 3.38 mu mol/kg). C14SS-DHA NPs showed significantly higher systemic exposure and better antimalarial activity in comparison with C14-CC-DHA NPs or DHA solution (P < 0.05).