DIOXOLANE NUCLEOSIDES AS ANTIVIRAL AGENTS

描述（由申请人提供）：随着时间的推移，HIV会有效地对抗病毒药物产生耐药性。因此，迫切需要更好的药物来治疗艾滋病毒，特别是耐药的艾滋病毒菌株。最近，D-FDOC, (-)- β -d -5-氟-1-[2-（羟甲基）-1,3-二恶唑兰-4-基]胞嘧啶，被证明对HIV耐药菌株具有有效的体外活性（对HIV- 1lai的EC50为0.04,μ M），而不会与3TC、AZT或奈韦拉平产生交叉耐药。D-FDOC在培养中对HBV也有效。在小鼠原代骨髓细胞中，即使在300 μ m时，D-FDOC也没有显示乳酸产量的增加。相反，与未处理的对照相比，L-FDOC处理导致乳酸产量增加了300倍。制备对映体纯度高的D-FDOC是避免合成过程中被污染的L-FDOC产生潜在毒性的重要因素。然而，由于缺乏大规模制备这种核苷的有效方法，D-FDOC的临床前和临床开发一直受到阻碍。因此，在第一阶段，我们将开发大规模合成d -二恶烷核苷的简便方法。这种化学反应不仅对Pharmasset有用，而且对其他开发二恶唑烷核苷的公司也有用，比如Triangle Pharmaceuticals的(-)- β -d -2,6-二氨基-9-[2-（羟甲基）-1,3-二恶唑烷-4-基]嘌呤（DAPD）。Ohrui等人报道，2'-脱氧-4'- c -乙基核苷在体外对HIV-1表现出有效的活性，EC50值在0.0003-0.03 μ m之间。2'- c -甲基核糖-戊呋喃基胞嘧啶也显示出有效的抗黄病毒活性。基于这些发现，我们建议设计和合成新的外消旋二恶烷核苷，特别是2'-C-乙基和5'-C-甲基取代二恶烷核苷，作为丙型肝炎病毒（HCV）和/或HIV的抗病毒药物。根据这些化合物的生物学测试结果，我们将利用新的工艺化学合成更多的活性对构象。在第二阶段，我们将应用我们最好的方法大规模合成D-FDOC，以及最有前途的新二恶烷核苷，进一步开发IND应用。

DESCRIPTION (provided by applicant): HIV efficiently develops resistance to antiviral agents over time. Thus, there is an urgent need for better agents to treat HIV, especially drug-resistant strains of HIV. Recently, D-FDOC, (-)-beta-D-5-fluoro-1-[2-(hydroxymethyl)-1,3-dioxolan-4-yl]cytosine, was shown to have potent in vitro activity against drug-resistant strains of HIV (EC50 against HIV-1LAI is 0.04, mu M) without producing cross-resistance with 3TC, AZT or nevirapine. D-FDOC is also effective against HBV in culture. In primary mouse bone marrow cells, D-FDOC demonstrated no increase in lactic acid production even at 300 mu M. In contrast, treatment with L-FDOC resulted in a > 300-fold increase relative to untreated control. It is important to prepare enantiomerically pure D-FDOC to avoid potential toxicity from contaminated L-FDOC in the synthesis. However, pre-clinical and clinical development of D-FDOC has been hampered by the lack of an efficient procedure for large-scale preparation of this nucleoside. Thus, during Phase I, we will develop facile methods for the large-scale synthesis of D-dioxolane nucleosides. This chemistry will be useful not only to Pharmasset, but to other companies developing dioxolane nucleosides such as (-)-beta-D-2,6- diamino-9-[2-(hydroxymethyl)-1,3-dioxolan-4-yl]purine (DAPD) by Triangle Pharmaceuticals. Ohrui et al reported that 2'-deoxy-4'-C-ethynyl-ribo-nucleosides showed potent activity against HIV-1 in vitro with EC50 values ranging from 0.0003-0.03 mu M. 2'-C-Methyl-ribo-pentofuranosylcytosine was also shown to have potent anti-flavivirus activity. Based on these findings, we propose to design and synthesize novel racemic dioxolane nucleosides, in particular 2'-C-ethynyl and 5'-C-methyl substituted dioxolane nucleosides as antiviral agents for hepatitis C virus (HCV) and/or HIV in Phase I. Based on results from the biological testing of these compounds, we will then identify more active enantiomers for synthesis using the new process chemistry. In Phase II, we will apply our best methodology for large-scale synthesis of D-FDOC as well as the most promising new dioxolane nucleoside for further development towards an IND application.