转运体介导的肾靶向雷公藤内酯醇前体药物TPS-L-Carnitine的合成及体外细胞摄取研究

Cellular Uptake of TPS-L-Carnitine Synthesised as Transporter-based Renal Targeting Prodrug

目的研究有机阳离子转运体(OCTN2)介导的肾靶向雷公藤内酯醇(TP)前体药物TP丁二酸酯(TPS)-L-肉毒碱(TPS-L-Carnitine)的合成方法和体外靶向细胞摄取。方法将TP与丁二酸酐在碱性条件下生成TPS,再与L-肉毒碱成酯得前体药物TPS-L-Carnitine,利用OCTN2对L-肉毒碱的特异性识别和结合,使前药主动靶向到肾近端小管上皮细胞。初步研究不同温度、浓度以及竞争抑制剂存在时人近端小管上皮细胞株HK-2细胞对前药和母体药物的摄取。结果 HK-2细胞对前药的吸收可饱和,具有温度和浓度依赖性,可被竞争抑制剂抑制,37℃相同给药浓度时,细胞对TPS-L-Carnitine的摄取明显多于TP,证实细胞对TPS-L-Carnitine的摄取机制是通过转运体介导的内吞作用。结论 TPS-L-Carnitine具有良好的肾靶向性,为进一步体内肾靶向研究奠定了基础。

Objective To synthesize transporter-based renal targeting prodrug TPS-L-Carnitine and to determine its cellular uptake in vitro. Methods Triptolide （TP） was conjugated with L-carnitine using succinate as the linker to form TPS-L-Carnitine, which could be specifically recognized by OCTN2, a cationic transporter with high affinity to L-Carnitine and is highly expressed on the apical membrane of renal proximal tubule cells. Cellular uptake assays of the prodrug and its parent drug were performed on HK-2 cells, a human proximal tubule cell line, in different temperature, concentration and in the presence of competitive inhibitors. Results TPS-L-Carnitine was taken up into HK-2 cells in a saturable and temperature- and concentration-dependent manner. The uptake process could be inhibited by the competitive inhibitors. The uptake of TPS-L-Carnitine was significantly higher than that of TP at 37℃ in the same drug concentration. TPS-L-Carnitine was taken through endocytosis mediated by transporter. Conclusion TPS-L-Carnitine provides a good renal targeting property and lays the foundation for further studies in vivo.