Bifunctional peptidomimetic prodrugs of didanosine for improved intestinal permeability and enhanced acidic stability: synthesis, transepithelial transport, chemical stability and pharmacokinetics.
Bifunctional peptidomimetic prodrugs of didanosine for improved intestinal permeability and enhanced acidic stability: synthesis, transepithelial transport, chemical stability and pharmacokinetics.
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DOI：
10.1021/mp100376q
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发表时间：
2011-03
影响因子：
4.9
通讯作者：
Zhongtian Yan;Jin Sun;Yannan Chang;Yanhua Liu;Q. Fu;Youjun Xu;Yongbing Sun;Xiaohui Pu;Youxi Zhang;Y. Jing;Shiliang Yin;Meng Zhu;Yongjun Wang;Zhonggui He
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文献类型：
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作者：
Zhongtian Yan;Jin Sun;Yannan Chang;Yanhua Liu;Q. Fu;Youjun Xu;Yongbing Sun;Xiaohui Pu;Youxi Zhang;Y. Jing;Shiliang Yin;Meng Zhu;Yongjun Wang;Zhonggui He
合成了五种去羟肌苷 (DDI) 的拟肽前药，旨在通过靶向肠道寡肽转运蛋白 (PepT1) 和增强化学稳定性来提高口服给药后 DDI 的生物利用度。在可渗透支持物上生长的 Caco-2 细胞中筛选前药的渗透性。 DDI 的 5'-O-L-缬氨酰酯前药（化合物 4a）表现出最高的膜渗透性，被选为进一步研究的最佳目标前药。化合物 4a 可以以浓度依赖性方式抑制 Caco-2 细胞对甘氨酰肌氨酸（Gly-Sar，PepT1 的典型底物）的摄取。 Caco-2 细胞用 0.2 nM 瘦素处理以增强 PepT1 表达。与对照Caco-2细胞相比，瘦素处理的Caco-2细胞中化合物4a的摄取显着增加，两者均被20 mM Gly-Sar明显抑制。 Caco-2细胞中PepT1转运化合物4a的动力学研究的K(m)和V(max)值分别为0.91 mM和11.94 nmol/mg蛋白质/10分钟。化学稳定性研究在模拟胃液 (SGF)、各种 pH 条件下的磷酸盐缓冲液、大鼠组织匀浆和 37°C 血浆中进行。在SGF中两分钟内无法检测到DDI的浓度。但化合物4a可以显着提高DDI的酸性稳定性，并且其在SGF中的t(½)延长至长达36分钟。化合物 4a 在 pH 6.0 磷酸盐缓冲液中稳定，但在血浆和组织匀浆中可快速转化为 DDI。将化合物4a和DDI以15mg/kg的剂量口服给予大鼠后，DDI的口服绝对生物利用度分别为47.2%和7.9%。与抗酸剂的共同给药也表明，与 DDI 相比，化合物 4a 在严酷的酸性条件下更稳定。当与 Gly-Sar (100 mg/kg) 共同口服给药时，化合物 4a 在大鼠中的生物利用度降低至 33.9%。通过比较大鼠颈静脉和门静脉中 DDI 和化合物 4a 的水平，研究了化合物 4a 的体内生物活化机制。完整化合物4a的血浆浓度在门静脉中非常低并且在颈静脉中几乎检测不到。总之，化合物4a可以通过PepT1介导的吸收和增强的酸性稳定性显着提高DDI在大鼠中的口服生物利用度，随后快速且主要在细胞内生物活化，大部分在肠细胞中，但少数在肝脏中。此外，针对肠道 PepT1 的前药策略可以提供一种有前途的策略，以提高吸收不良的去羟肌苷的口服生物利用度。
Five peptidomimetic prodrugs of didanosine (DDI) were synthesized and designed to improve bioavailability of DDI following oral administration via targeting intestinal oligopeptide transporter (PepT1) and enhancing chemical stability. The permeability of prodrugs was screened in Caco-2 cells grown on permeable supports. 5'-O-L-valyl ester prodrug of DDI (compound 4a) demonstrated the highest membrane permeability and was selected as the optimal target prodrug for further studies. The uptake of glycylsarcosine (Gly-Sar, a typical substrate of PepT1) by Caco-2 cells could be inhibited by compound 4a in a concentration-dependent manner. The Caco-2 cells were treated with 0.2 nM leptin for enhanced PepT1 expression. The uptake of compound 4a was markedly increased in the leptin-treated Caco-2 cells compared with the control Caco-2 cells, both of which were obviously inhibited by 20 mM Gly-Sar. The K(m) and V(max) values of kinetic study of compound 4a transported by PepT1 in Caco-2 cells were 0.91 mM and 11.94 nmol/mg of protein/10 min, respectively. The chemical stability studies were performed in simulated gastric fluid (SGF), phosphate buffers under various pH conditions, rat tissue homogenates and plasma at 37 °C. The concentrations of DDI could not be detected in the two minutes in SGF. But compound 4a could significantly increase DDI acidic stability, and its t(½) was extended to as long as 36 min in SGF. Compound 4a was stable in pH 6.0 phosphate buffer but could be quickly transformed into DDI in plasma and tissue homogenates. The oral absolute bioavailability of DDI was 47.2% and 7.9% after compound 4a and DDI were orally administered to rats at a dose of 15 mg/kg, respectively. The coadministration with antiacid agent could also suggest that compound 4a was more stable under harsh acidic conditions compared with DDI. Compound 4a bioavailability in rats was reduced to 33.9% when orally co-administered with Gly-Sar (100 mg/kg). The In Vivo bioactivation mechanism of compound 4a was investigated by comparing the levels of DDI and compound 4a in the jugular and portal veins in rats. The plasma concentration of intact compound 4a was very low in portal veins and could hardly be detected in the jugular vein. In conclusion, compound 4a could significantly improve the oral bioavailability of DDI in rats through PepT1-mediated absorption and enhanced acidic stability, followed by rapid and mostly intracellular bioactivation, the majority in the intestinal cells but the minority in the liver. Additionally, the prodrug strategy targeted to intestinal PepT1 could offer a promising strategy to improve oral bioavailability of poorly absorbed didanosine.