胶束化色胺酮的制备及表征

目的通过制备胶束化色胺酮,增加色胺酮的溶解度,并进一步提高其生物利用度。方法:以酸敏感的腙键连接聚乙二醇和色胺酮,并通过透析法,将聚乙二醇化色胺酮进一步制备成胶束。用动态光散射法测定胶束的粒径分布用透射电镜观察胶束的形貌。通过芘荧光探针法测定胶束的临界胶束浓度。测定胶束在不同pH下的药物释放情况(pH5.5和7.4)。采用薄层色谱法和高效液相色谱法研究腙键的断裂行为。通过CCK-8法比较生理pH和酸性pH下,色胺酮和聚乙二醇化色胺酮胶束(PTMs)对MCF-7细胞的体外细胞毒性。结果:与色氨酸相比,PTMs的溶解度提高了1493倍。制备的胶束粒径为228.8 nm,PDI为0.1,形貌为球形。PTMs的临界胶束浓度为3.5×10^-7mol/L,较低的CMC值表明制备的胶束稳定性高,便于进一步使用。腙键可在酸性条件下发生断裂,且在pH 5.5下,12 h内95%的色胺酮从胶束中释放,而在生理pH下(pH 7.4),药物释放缓慢。在生理条件下胶束的细胞毒性低于色胺酮,说明胶束化色胺酮可降低药物毒性及胶束在生理条件下有一定的稳定性。而在pH 5.5时,色胺酮胶束与色胺酮的细胞毒性相近表明胶束可响应肿瘤细胞内的低pH值成功实现药物释放。结论:胶束化色胺酮不仅能有效改善色胺酮的溶解度,有利于进一步提高其生物利用度,而且是一种很有应用前景的肿瘤靶向前药。

Preparation and Characterization of Micellar Tryptanthrin

ABSTRACT Objective: The study was aimed to increase the solubility of tryptanthrin (TRYP) by preparing micellar tryptanthrin, improve its bioavailability further. Methods: Pegylated tryptanthrin was synthesized via acid-sensitive hydrazone bond and further prepared as micelles by employing the dialysis method. The particle size distribution of the micelles was evaluated by dynamic light scattering (DLS) and the morphology was observed using a transmission electron microscope. The critical micelle concentration (CMC) of micelles was estimated by fluorescence probe method. The in vitro drug-release profile was determined using a dynamic dialysis method at pH 5.5 and pH 7.4. The fracture behavior of hydrazone bond was studied by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). In vitro cytotoxicity of TRYP and PEGylated tryptanthrin micelles (PTMs) against MCF-7 cells was studied using the CCK-8 assay. Results: The solubility of PTMs was increased by 1493 fold compared with TRYP. The PTMs were prepared with a particle size of 228.8 nm and PDI of 0.1, and the micelles were spherical. The CMC of PTMs was 3.5×10^-7 mol/L and the low CMC indicated the high stability of prepared micelles and facilitated further use. The fracture behavior of hydrazone bond at acidic pH was verified and 95% of TRYP was released from PTMs at lower pH 5.5 in 12 h, while the drug release was very slow at normal physiological pH 7.4. The cytotoxicity of PTMs decreased under normal physiological conditions compared with TRYP, indicating that the cytotoxicity of PTMs was reduced compared with that of TRYP, which may be due to the stability of TRYP when prepared as micelles. Whereas at pH 5.5, the PTMs showed comparable cytotoxicity, indicating successful drug release from the carrier in response to tumor intracellular pH. Conclusion: The pegylated tryptanthrin improved water solubility of tryptanthrin effectively, which would benefit its further improvement in its bioavailability. Besides, it could be a promising tumor targeting prodrug.