Bronson J J, Ho H T, De Boeck H, Woods K, Ghazzouli I, Martin J C, Hitchcock M J
Bristol-Myers Squibb, Pharmaceutical Research and Development Division, Wallingford, Connecticut 06492-7660.
Ann N Y Acad Sci. 1990;616:398-407. doi: 10.1111/j.1749-6632.1990.tb17859.x.
Our studies have shown that the acyclic nucleotide analogues PMEA and HPMPC are able to penetrate into cells and are then activated to mono- and diphosphate derivatives. The latter correspond to triphosphate analogues and presumably serve an important role in the biological activity exerted by these antiviral agents. In support of this idea, the inhibitory effect of PMEApp on HIV reverse transcriptase has been demonstrated with both RNA and DNA template-primer systems. Further studies will be undertaken to determine the effect of HPMPCpp on viral DNA polymerases. Whereas the metabolism of PMEA in CEM cells gives rise to only PMEAp and PMEApp, additional metabolites were obtained in MRC-5 cells; the identity of these metabolites remains to be determined. In the case of HPMPC, a third metabolite was obtained in addition to HPMPCp and HPMPCpp, which has been tentatively assigned as a phosphate-choline adduct by analogy with activation of cytosine-based nucleoside derivatives. The metabolism of HPMPC was unchanged between uninfected and infected cells, indicating that viral enzymes are not necessary for the activation of HPMPC. The long intracellular half-lives of the HPMPC metabolites may have implications for the antiviral efficacy of this compound. The persistence of activated metabolites suggests that infrequent dosing may be possible due to a prolonged antiviral effect. Our results on the effectiveness of infrequent dosing schedules with HPMPC in the treatment of HSV 2 infections in mice support this hypothesis. It is also possible that HPMPCp-choline may serve as a reservoir for HPMPC and therefore for the presumed active metabolite HPMPCpp.
我们的研究表明，无环核苷酸类似物PMEA和HPMPC能够穿透细胞，然后被激活形成单磷酸和二磷酸衍生物。后者相当于三磷酸类似物，可能在这些抗病毒药物发挥的生物活性中起重要作用。支持这一观点的是，在RNA和DNA模板-引物系统中均已证明PMEApp对HIV逆转录酶具有抑制作用。将进一步开展研究以确定HPMPCpp对病毒DNA聚合酶的作用。虽然PMEA在CEM细胞中的代谢仅产生PMEAp和PMEApp，但在MRC-5细胞中获得了其他代谢产物；这些代谢产物的身份仍有待确定。就HPMPC而言，除了HPMPCp和HPMPCpp外，还获得了第三种代谢产物，通过与基于胞嘧啶的核苷衍生物的激活进行类比，暂时将其指定为磷酸胆碱加合物。HPMPC在未感染和感染细胞之间的代谢没有变化，这表明病毒酶对于HPMPC的激活不是必需的。HPMPC代谢产物较长的细胞内半衰期可能对该化合物的抗病毒疗效有影响。活化代谢产物的持续存在表明，由于抗病毒作用延长，可能可以减少给药频率。我们关于HPMPC不频繁给药方案治疗小鼠单纯疱疹病毒2感染有效性的结果支持这一假设。HPMPCp-胆碱也有可能作为HPMPC的储存库，因此也可能是假定的活性代谢产物HPMPCpp的储存库。
