Preparation, In Vitro And In Vivo Evaluation Of Brain-Targeting β-Cyclodextrin Derivative

Brain diseases such as neurodegenerative diseases threat human health. Due to the complicated brain structure, most drugs and diagnostic agents are failed to pass through the blood-brain barrier for effective drug concentration in the brain. The object of this study is to useβ-cyclodextrin derivatives as drug carriers, transferrins (Tf) or lactoferrins (Lf) with high brain-targeting transport effiencies as target ligands, constructing a novel brain-targetingβ-cyclodextrin derivative drug delivery system.Mono-6-deoxy-6-(ρ-tolylsulfonyl)-β-cyclodextrin intermediates were synthesized in alkaline aqueous solution, then modified by anhydrous enthylenediamine (EDA), obtained mono-6-deoxy-(6-aminoethylamino)-β-cyclodextrin (EDA-CD). The structure was confirmed by MS,'H-NMR methods. Tf or Lf was selected as a brain-targeting ligand conjugated to EDA-CD via heterobifunctional polyethyleneglycol derivative (NHS-PEG5000-MAL) as a linker, Tf-PEG5000-CD or Lf-PEG5000-CD as the novel drug delivery system was obtained. UV, FITR and 1H-NMR results demonstrated the successful synthesis of Tf-PEG5000-CD and Lf-PEG5000-CD. By determining Tf and Lf content using Bradford method, final yields of Tf-PEG5000-CD and Lf-PEG5000-CD were (85.0±3.6)% and (91.1±2.4)%, respectively. The brain-targetingβ-cyclodextrin derivatives were oval in shape with the size of (92.9±16.5) nm through transmission electron microscopy observation.Using near infrared fluorescent dye IR-775 as the model drug, Tf-PEG5000-CD inclusion complexes of IR-775 (Tf-CD/IR) and Lf-PEG5000-CD inclusion complexes of IR-775 (Lf-CD/IR) were prepared by freeze drying method. The entrapment rates of Tf-CD/IR and Lf-CD/IR were (97.3±4.5)% and (98.1±4.8)%, respectively.Pharmacokinetics and biodistribution were evaluated in KM mice after intravenous administration (equiv. dose,5μg IR per mouse). Drug concentrations were determined by fluorescence spectroscopy. The samples in plasma or organs were collected at different time points to measure the concentrations of drugs, drug concentration-time curves were drawn and pharmacokinetic parameters were calculated. Results showed that AUCo-2h of IR in plasma and brain of the Lf-CD/IR treatment were 4.1-and 6.9-fold that of IR treatment, respectively. Compared to drug concentrations of IR treatment, the drug concentrations of Lf-CD/IR treatment in brain were 6.8-fold at 90 min and 7.9-fold at 120 min, after KM mice administrated, showing the high transport efficiency in brain when PEG chain, Tf or Lf was introduced. In vivo imaging study on BALB/cASlac nude mice confirmed the high brain delivery efficiency of Lf-CD/IR with the high fluorescent intensity. This novelβ-cyclodextrin derivative drug delivery system can be exploited as a potential brain-targeting drug carrier for drug application on neurological diseases and diagnostic reagents.