Zein-derived peptides as nanocarriers to increase the water solubility and stability of lutein

Zein and its derived peptides have been used as nanocarriers for bioactive components. Lutein, as well as other xanthophylls, are characterized by blue light filtering and anti-oxidant properties. However, lutein is unstable and has low water solubility, poor absorption, and low bioavailability. In order to protect lutein from oxidative degradation, and to enhance its solubility and dispersibility, stability and bioactivity, lutein-loaded zein nanoparticles (LLZ-NP) and zein-derived peptide nanoparticles (LLZ-PEP-NP) were prepared by the solvent diffusion method. Compared to LLZ-NP, LLZ-PEP-NP possessed good physicochemical properties, including particle size, polydispersity index, zeta potential, entrapment efficiency and in vitro stability. Specifically, transmission electron microscopy (TEM) images showed that LLZ-PEP-NP had a spherical form with a nanometric size and lutein was efficiently loaded into zein-derived peptides through self-assembly. Dynamic light scattering (DLS) results demonstrated that LLZ-PEP-NP had a narrow size distribution in the range of 200–300 nm and a decreased zeta potential compared to that of LLZ-NP. The lutein entrapment efficiency (EE%) of LLZ-NP and LLZ-PEP-NP was more than 85%, while LUT-PEP-NP showed higher lutein entrapment efficiency because of the better capacity of peptides bound with lutein. Nanoencapsulation of lutein into LLZ-PEP-NP resulted in a significantly higher solubility compared to nanoencapsulation of lutein into LLZ-NP and free lutein. The stabilities of lutein in zein-derived peptide nanoparticles in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were improved. These results suggest that zein-derived peptides have the potential to be used as nanocarriers to enhance the solubility and stability of lutein, which can further improve its bioavailability.