School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China.
School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189, China.
Biomaterials. 2018 May;163:76-87. doi: 10.1016/j.biomaterials.2018.02.026. Epub 2018 Feb 10.
Artemisinin and its derivatives are highly effective drugs in the treatment of P. falciparum malaria. However, their clinical applications face challenges because of short half-life, poor bioavailability and growing drug resistance. In this article, novel dimeric artesunate phospholipid (Di-ART-GPC) based liposomes were developed by combination of dimerization and self-assembly to address these shortcomings. Firstly, Di-ART-GPC conjugate was synthesized by a facile esterification of artesunate (ART) and glycerophosphorylcholine (GPC) and confirmed by MS, H NMR and C NMR. The conjugate was then assembled to form liposomes without excipient by thin film hydration method. The assembled Di-ART-GPC liposomes have typical multilamellar vesicle structure with bilayer morphology as determined by transmission electron microscopy (TEM) and cryogenic electron microscopy (cryo-EM). Moreover, the liposomes displayed an average hydrodynamic diameter of 190 nm and negative zeta potential at -20.35 mV as determined by Zetasizer. The loading capacity of ART was calculated approximately 77.6% by weight with this liposomal formulation after a simple calculation. In vitro drug release and degradation results showed that the Di-ART-GPC liposomes were stable in neutral physiological conditions but effectively degraded to release parent ART in simulated weakly acidic microenvironment. In vivo pharmacokinetics study revealed that Di-ART-GPC liposomes and conjugate have longer retention half-life in bloodstream. Importantly, Di-ART-GPC liposomes (IC 0.39 nM) and the conjugate (IC 1.90 nM) demonstrated excellent in vitro antiplasmodial activities without causing hemolysis of erythrocytes, which were superior to free ART (IC 5.17 nM) and conventional ART-loaded liposomes (IC 3.13 nM). Furthermore, the assembled liposomes resulted in enhanced parasites killing in P. berghei-infected mice in vivo with delayed recrudescence and improved survivability, compared to free ART administration. Based on these encouraging results, Di-ART-GPC liposomal formulation could be a replacement to parent ART in clinical malarial therapy after thorough investigation.
青蒿素及其衍生物是治疗恶性疟原虫疟疾的高效药物。然而，由于半衰期短、生物利用度差和耐药性增加，它们的临床应用面临挑战。在本文中，通过二聚化和自组装相结合，开发了新型二聚青蒿琥酯磷脂（Di-ART-GPC）脂质体，以解决这些缺点。首先，通过青蒿琥酯（ART）和甘油磷酸胆碱（GPC）的简单酯化合成 Di-ART-GPC 缀合物，并通过 MS、H NMR 和 C NMR 进行确认。然后，通过薄膜水化法将缀合物组装成无赋形剂的脂质体。组装后的 Di-ART-GPC 脂质体具有典型的多层囊泡结构，双层形态通过透射电子显微镜（TEM）和冷冻电子显微镜（cryo-EM）确定。此外，通过 Zetasizer 确定脂质体的平均水动力直径为 190nm，zeta 电位为-20.35mV。通过简单计算，该脂质体制剂的 ART 载药量约为 77.6%。体外药物释放和降解结果表明，Di-ART-GPC 脂质体在中性生理条件下稳定，但在模拟弱酸性微环境中有效降解以释放母体 ART。体内药代动力学研究表明，Di-ART-GPC 脂质体和缀合物在血液中的保留半衰期更长。重要的是，Di-ART-GPC 脂质体（IC 0.39nM）和缀合物（IC 1.90nM）表现出优异的体外抗疟原虫活性，而不会引起红细胞溶血，优于游离 ART（IC 5.17nM）和常规 ART 负载脂质体（IC 3.13nM）。此外，与游离 ART 给药相比，组装后的脂质体在体内感染伯氏疟原虫的小鼠中导致寄生虫杀伤增强，复发延迟，存活率提高。基于这些令人鼓舞的结果，Di-ART-GPC 脂质体制剂在经过彻底研究后，可替代临床疟疾治疗中的母体 ART。
