We assessed factors that determine the tissue-specific bioactivation of ProTide prodrugs by comparing the disposition and activation of remdesivir (RDV), its methylpropyl and isopropyl ester analogues (MeRDV and IsoRDV, respectively), the oral prodrug GS-621763, and the parent nucleotide GS-441524 (Nuc). RDV and MeRDV yielded more active metabolite remdesivir-triphosphate (RDV-TP) than IsoRDV, GS-621763, and Nuc in human lung cell models due to superior cell permeability and higher susceptivity to cathepsin A. Intravenous administration to mice showed that RDV and MeRDV delivered significantly more RDV-TP to the lung than other compounds. Nevertheless, all four ester prodrugs exhibited very low oral bioavailability (<2%), with Nuc being the predominant metabolite in blood. In conclusion, ProTides prodrugs, such as RDV and MeRDV, are more efficient in delivering active metabolites to the lung than Nuc, driven by high cell permeability and susceptivity to cathepsin A. Optimizing ProTides’ ester structures is an effective strategy for enhancing prodrug activation in the lung.

中文翻译：

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不同 GS-441524 前药在细胞和小鼠模型中的生物活性差异：具有高细胞渗透性和对组织蛋白酶 A 敏感性的 ProTide 前药能够更有效地将抗病毒活性代谢物输送至肺部

我们通过比较瑞德西韦 (RDV)、其甲基丙酯和异丙酯类似物（分别为 MeRDV 和 IsoRDV）、口服前药 GS-621763 和母体核苷酸的处置和激活，评估了决定 ProTide 前药组织特异性生物活性的因素GS-441524（Nuc）。在人肺细胞模型中，RDV 和 MeRDV 由于具有优异的细胞通透性和对组织蛋白酶 A 的敏感性更高，因此比 IsoRDV、GS-621763 和 Nuc 产生了更活跃的代谢物瑞德西韦三磷酸 (RDV-TP)。对小鼠进行静脉注射表明，RDV 和 MeRDV与其他化合物相比，向肺部输送的 RDV-TP 明显更多。然而，所有四种酯前药均表现出非常低的口服生物利用度（<2%），其中 Nuc 是血液中的主要代谢物。总之，ProTides 前药（例如 RDV 和 MeRDV）在将活性代谢物递送至肺部方面比 Nuc 更有效，这是由于高细胞渗透性和对组织蛋白酶 A 的敏感性所致。优化 ProTides 的酯结构是增强前药激活的有效策略。肺。