Novartis Institute for Tropical Diseases, 10 Biopolis Road, #05-01 Chromos, Singapore 138670, Singapore.
Antimicrob Agents Chemother. 2010 Aug;54(8):3255-61. doi: 10.1128/AAC.00397-10. Epub 2010 Jun 1.
Dengue virus (DENV) is the most prevalent mosquito-borne viral pathogen that infects humans. Neither a vaccine nor an antiviral therapy is currently available for DENV. Here, we report an adenosine nucleoside prodrug that potently inhibits DENV replication both in cell culture and in a DENV mouse model. NITD449 (2'-C-acetylene-7-deaza-7-carbamoyladenosine) was initially identified as a parental compound that inhibits all four serotypes of DENV with low cytotoxicity. However, in vivo pharmacokinetic studies indicated that NITD449 had a low level of exposure in plasma when dosed orally. To increase the oral bioavailability, we covalently linked isobutyric acids to the 3'- and 5'-hydroxyl groups of ribose via ester linkage to NITD449, leading to the prodrug NITD203 (3',5'-O-diisobutyryl-2'-C-acetylene-7-deaza-7-carbamoyl-adenosin). Pharmacokinetic analysis showed that upon oral dosing of the prodrug, NITD203 was readily converted to NITD449, resulting in improved exposure of the parental compound in plasma in both mouse and rat. In DENV-infected AG129 mice, oral dosing of the prodrug at 25 mg/kg of body weight reduced peak viremia by 30-fold. Antiviral spectrum analysis showed that NITD203 inhibited various flaviviruses (DENV, yellow fever virus, and West Nile virus) and hepatitis C virus but not Chikungunya virus (an alphavirus). Mode-of-action analysis, using a luciferase-reporting replicon, indicated that NITD203 inhibited DENV RNA synthesis. Although NITD203 exhibited potent in vitro and in vivo efficacies, the compound could not reach a satisfactory no-observable-adverse-effect level (NOAEL) in a 2-week in vivo toxicity study. Nevertheless, our results demonstrate that a prodrug approach using a nucleoside analog could potentially be developed for flavivirus antiviral therapy.
登革热病毒（DENV）是最常见的蚊媒病毒病原体，感染人类。目前既没有疫苗也没有抗病毒疗法可用于 DENV。在这里，我们报告了一种腺苷核苷前药，它在细胞培养和 DENV 小鼠模型中均能有效抑制 DENV 的复制。NITD449（2'-C-乙炔基-7-脱氮-7-甲酰基腺苷）最初被鉴定为一种亲本化合物，对所有四种血清型 DENV 均具有低细胞毒性。然而，体内药代动力学研究表明，当口服给药时，NITD449 在血浆中的暴露水平较低。为了提高口服生物利用度，我们通过酯键将异丁酸连接到核糖的 3'-和 5'-羟基上，得到前药 NITD203（3'，5'-O-二异丁酰基-2'-C-乙炔基-7-脱氮-7-甲酰基-腺苷）。药代动力学分析表明，口服给予前药后，NITD203 可迅速转化为 NITD449，从而提高母体化合物在血浆中的暴露水平，无论是在小鼠还是大鼠中。在 DENV 感染的 AG129 小鼠中，以 25mg/kg 体重口服给予前药可将峰值病毒血症降低 30 倍。抗病毒谱分析表明，NITD203 抑制各种黄病毒（DENV、黄热病病毒和西尼罗河病毒）和丙型肝炎病毒，但不抑制基孔肯雅病毒（一种甲病毒）。使用荧光素酶报告复制子的作用机制分析表明，NITD203 抑制 DENV RNA 合成。尽管 NITD203 表现出强大的体外和体内疗效，但在为期 2 周的体内毒性研究中，该化合物无法达到可接受的无观察不良效应水平（NOAEL）。尽管如此，我们的结果表明，使用核苷类似物的前药方法有可能用于黄病毒抗病毒治疗。
