Lutein Loaded in β-Cyclodextrin Metal-Organic Frameworks for Stability and Solubility Enhancements

Lutein (Lut) is a recognized nutritional supplement known for its antioxidative and anti-inflammatory properties, crucial in mitigating ocular disease. However, enhancements to Lut stability and solubility remain challenges to be addressed in the healthcare industry. Herein, we fabricated and evaluated a food-grade highly porous beta-cyclodextrin metal-organic framework (beta-CD-MOF) for its ability to encapsulate Lut. Lut stability considerably improved when loaded into beta-CD-MOF to form a Lut@beta-CD-MOF complex, which exhibited better stability than Lut loaded into the gamma-cyclodextrin metal-organic framework (Lut@gamma-CD-MOF), Lut@beta-CD, and commercial product (Blackmores (TM)) at 40 degrees C, 60 degrees C, and 70 degrees C, respectively. The solubility of Lut@beta-CD-MOF in water increased by 26.8-fold compared to raw Lut at 37 degrees C. Lut@beta-CD-MOF exhibited greater hydrophilicity, as determined by measuring the water contact angle. Molecular docking and other characterizations of Fourier transform infrared spectroscopy and powder X-ray diffraction confirmed that Lut was successfully encapsulated in the chamber formed by the three cyclodextrins in beta-CD-MOF. Thermogravimetric analysis and Raman spectroscopy demonstrated that Lut distributed in the beta-CD-MOF cavity deeply improved Lut stability and solubility. In conclusion, our findings underscored the function of beta-CD-MOF in enhancing Lut stability and solubility for formulation applications.Graphical AbstractThe helical structure of beta-CD-MOF was instrumental in deeply encapsulating the long-chain Lut molecule, effectively restricting its movement within the structure. This led to a significant improvement in the stability of Lut at 60 degrees C when loaded into beta-CDMOF. Moreover, upon interaction with water, the coordination bonds of beta-CD-MOF were disrupted to facilitate a superior dispersibility of the Lut molecule, leading to a remarkable 26.8-fold increase in solubility compared to raw Lut at 37 degrees C.