Native and β-cyclodextrin-enclosed curcumin: entrapment within liposomes and their in vitro cytotoxicity in lung and colon cancer

With a view to improving the solubility and delivery characteristics of poorly water-soluble drugs, we prepared beta-cyclodextrin-curcumin (beta CD-C)inclusion complexes (hydrophilic curcumin) and entrapped both native curcumin (hydrophobic) and the complexes separately into liposomes; these were then assessed for in vitro cytotoxicity in lung and colon cancer cell lines. Optimization of curcumin entrapment within beta CD was achieved, with the resultant beta CD-C complexes prepared by methanol reflux. Inclusion complexes were confirmed using UV spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction. The water solubility of beta CD-C complexes improved markedly (c.f. native curcumin) and successful entrapment of complexes into liposomes, prepared using a thin-film hydration approach, was also achieved. All the liposomal formulations were characterized for curcumin and beta CD-C complex entrapment efficiency, particle size, polydispersity and stability at 2-8 degrees C. Curcumin, beta CD-C complex and their optimized liposomal formulations were evaluated for anticancer activity in lung (A-459) and colon (SW-620) cancer cell lines. All curcumin-containing formulations tested were effective in inhibiting cell proliferation, as determined via an MTT assay. The median effective dose (EC50) for all curcumin formulations was found to be in the low mu M range for both lung and colon cancer cell lines tested. Our results confirm that beta CD inclusion complexes of poorly water soluble drugs, such as curcumin can be entrapped within biocompatible vesicles such as liposomes, and this does not preclude their anticancer activity.