Stabilization of Antitumor Agent Busulfan through Encapsulation within a Water-Soluble Pillar[5]arene.

The complexation of the antitumor agent busulfan by negatively charged carboxylatopillar[5]arene in water is reported. The encapsulation within carboxylatopillar[5]arene reduces the hydrolytic degradation of busulfan from 90.7% to 25.2% after 24 days and accordingly enhances its stability by providing a hydrophobic shelter for busulfan in water. Moreover, the complexation results in 12 times improvement of water solubility for busulfan. Our result provides a supramolecular approach for stabilizing the anticancer agent busulfan.