Preparation and characterization of spray dried complexes of lutein with cyclodextrins

Lutein (LUT) is one of the most important carotenoid and; the most prominent being its antioxidant activity. However, its use is limited due to poor solubility and instability under adverse conditions. An attempt is made to increase the solubility and hence bioavailability of LUT using various cyclodextrins viz., betacyclodextrin (beta CD), hydroxypropyl betacyclodextrin (HP-beta CD) and methyl betacyclodextrin (M-beta CD). Physical mixtures and spray dried inclusion complexes were prepared and characterized using spectroscopic techniques, DSC and XRD studies. From the phase solubility and dissolution studies it was found that, M-beta CD significantly improved the solubility of LUT. These complexes were further subjected to in vitro anti-proliferative activity in order to validate results obtained from solubility studies. The biological results were in congruence with the results of solubility studies. Spray dried complex of LUT: M-beta CD showed significant percent growth inhibition as compared to other two complexes and LUT alone. Molecular modeling studies established the hostguest stoichiometry with the lowest energy to be 2: 1, with the two hexatomic rings of a LUT molecule occupying the two M-beta CD cavities. The present study forms the basis for the development of oral formulations of LUT with significantly improved solubility and bioavailability.