Synthesis and Biological Evaluation of Novel Folic Acid Receptor-Targeted, β-Cyclodextrin-Based Drug Complexes for Cancer Treatment

Drug targeting is an active area of research and nano-scaled drug delivery systems hold tremendous potential for the treatment of neoplasms. In this study, a novel cyclodextrin (CD)-based nanoparticle drug delivery system has been assembled and characterized for the therapy of folate receptor-positive [FR(+)] cancer. Water-soluble folic acid (FA)-conjugated CD carriers (FACDs) were successfully synthesized and their structures were confirmed by 1D/2D nuclear magnetic resonance (NMR), matrix-assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOF-MS), high performance liquid chromatography (HPLC), Fourier transform infrared spectroscopy (FTIR), and circular dichroism. Drug complexes of adamatane (Ada) and cytotoxic doxorubicin (Dox) with FACD were readily obtained by mixed solvent precipitation. The average size of FACD-Ada-Dox was 1.5–2.5 nm. The host-guest association constant Ka was 1,639 M−1 as determined by induced circular dichroism and the hydrophilicity of the FACDs was greatly enhanced compared to unmodified CD. Cellular uptake and FR binding competitive experiments demonstrated an efficient and preferentially targeted delivery of Dox into FR-positive tumor cells and a sustained drug release profile was seen in vitro. The delivery of Dox into FR(+) cancer cells via endocytosis was observed by confocal microscopy and drug uptake of the targeted nanoparticles was 8-fold greater than that of non-targeted drug complexes. Our docking results suggest that FA, FACD and FACD-Ada-Dox could bind human hedgehog interacting protein that contains a FR domain. Mouse cardiomyocytes as well as fibroblast treated with FACD-Ada-Dox had significantly lower levels of reactive oxygen species, with increased content of glutathione and glutathione peroxidase activity, indicating a reduced potential for Dox-induced cardiotoxicity. These results indicate that the targeted drug complex possesses high drug association and sustained drug release properties with good biocompatibility and physiological stability. The novel FA-conjugated β-CD based drug complex might be promising as an anti-tumor treatment for FR(+) cancer.

药物靶向研究是当前的活跃研究领域，纳米级药物递送系统在肿瘤治疗中拥有巨大潜力。本研究组装并表征了一种新型基于环糊精（CD）的纳米颗粒药物递送系统，用于叶酸受体阳性（FR(+)）癌症的治疗。研究人员成功合成了水溶性叶酸（FA）偶联环糊精载体（FACDs），并通过一维/二维核磁共振（NMR）、基质辅助激光解吸电离飞行时间质谱（MALDI-TOF-MS）、高效液相色谱（HPLC）、傅里叶变换红外光谱（FTIR）以及圆二色谱对其结构进行了确证。采用混合溶剂沉淀法可便捷制备金刚烷（Ada）与细胞毒性阿霉素（Dox）和FACDs的药物复合物。FACD-Ada-Dox的平均粒径为1.5~2.5 nm。通过诱导圆二色谱测定得到其主客体结合常数Ka为1639 M⁻¹；与未修饰的环糊精相比，FACDs的亲水性得到显著提升。细胞摄取与FR结合竞争性实验结果表明，该系统可将阿霉素高效且靶向性地递送至FR阳性肿瘤细胞，体外实验显示其具备持续的药物释放特性。共聚焦显微镜观察到，药物可通过内吞作用将阿霉素递送至FR(+)癌细胞，且靶向纳米颗粒的药物摄取量是非靶向药物复合物的8倍。分子对接结果显示，FA、FACD以及FACD-Ada-Dox均可与包含FR结构域的人类刺猬因子相互作用蛋白结合。经FACD-Ada-Dox处理的小鼠心肌细胞与成纤维细胞，其活性氧水平显著降低，谷胱甘肽含量与谷胱甘肽过氧化物酶活性均有所提升，这表明阿霉素诱导的心脏毒性风险有所降低。上述结果表明，该靶向药物复合物具备高药物结合能力与持续药物释放特性，同时拥有良好的生物相容性与生理稳定性。这种新型基于β-环糊精的叶酸偶联药物复合物有望成为FR(+)癌症的抗肿瘤治疗候选方案。