Solubility and biological activity enhancement of docetaxel via formation of inclusion complexes with three alkylenediamine-modified β-cyclodextrins

Docetaxel (DTX) is an effective and commonly used chemotherapeutic drug for cancer. However, its efficacy is greatly compromised because of its toxicity and poor water solubility. In order to overcome these disadvantages, three inclusion complexes between DTX and alkylenediamine-modified β-cyclodextrins (H1–3) with ethylene, propylene and butylene segments were prepared and characterized. The phase solubility studies demonstrated that the stoichiometry of the inclusion complexes between H1–3 and DTX were 1 : 1. The binding abilities of host H1–3 towards DTX decrease in the following order: H3 > H2 > H1, which had good consistency with the decreasing alkylene lengths of these hosts. The water solubility of DTX is remarkably increased 216, 242 and 253 times after forming inclusion complexes with H1–3, respectively. In vitro release studies of DTX from H1–3/DTX into NaAc–HAc buffer solution (pH 5.0) or PBS (pH 7.4) exhibited a preliminary stage burst effect and followed by a slow drug release. The cytotoxicity studies revealed that the H1–3/DTX inclusion complexes exhibited better cytotoxicity profiles against MCF-7, SW480 and A-549 cells than that of DTX. Furthermore, compared with the treatment of DTX, the H1/DTX inclusion complex significantly increased the cell apoptosis percentage from 17.2% to 30.2% (5 μg mL−1), 19.0% to 31.0% (10 μg mL−1), and 19.3% to 32.2% (15 μg mL−1), respectively. These results will provide useful information for H1–3/DTX inclusion complexes as safe and efficient anticancer drug formulations.