Lutein and β-carotene characterization in free and nanodispersion forms in terms of antioxidant activity and cytotoxicity

Abstract Purpose: Carotenoids are potent natural antioxidants with many important applications. Their nanodispersion formulations can solve problems that may limit their usage. In this study, we produced carotenoid nanodispersions from extracted lutein (Nano-Lut), extracted β-carotene (Nano-EBc), and synthetic β-carotene (Nano-SBC). Methods: The present study has quantitatively emphasized the physicochemical, antioxidant, and cytotoxic properties of free and nanodispersed formulations of lutein and β-carotene. The nanodispersions were characterized by spectral absorption, dynamic light scattering, and zeta potential. Antioxidant and cytotoxicity assays were conducted for free and their nanodispersed forms. The cytotoxicity of free carotenoids and their nanodispersions was conducted on HSF, VERO, and BNL cell lines. Results: Nano-Lut has the smallest mean particle size (185.2 ± 40.5 nm, PDI of 0.183 ± 0.01, and zeta potential of -28.6 ± 6.4 mV). Nano-SBc showed monomodal size distribution (220.5 ± 30.09 nm, PDI of 0.318 ± 0.03, and zeta potential of -12.1 ± 5.9 mV), while Nano-EBc showed a bimodal size distribution (with a mean particle size of 498.3 ± 88.9 nm, PDI of 0.65 ± 0.08, and zeta potential of -39.7 ± 1.3 mV). All prepared nanodispersions showed less than 20% loss during the formulation process. Antioxidant assays showed that extracted lutein was the most active and synthetic β-carotene was the least. Cells showed higher tolerance for lutein and its nanodispersion than extracted or synthetic β-carotene either in free or nanodispersion forms. Conclusions: The study proved that lutein in nanodispersed form possesses the smallest size, the highest antioxidant activity, and the lowest cytotoxicity among the tested formulations.