Lutein encapsulated oleic - linoleic acid nanoemulsion boosts oral bioavailability of retinal protective carotenoid lutein in rat model

Abstract

There is excessive interest in emerging colloidal delivery systems to enhance the water solubility and oral bioavailability of lutein, which is a hydrophobic carotenoid claimed to possess health benefits. The present study aimed to design lutein-enriched nanoemulsions with improved physicochemical properties and to achieve various health benefits of lutein. The prepared lutein nanoemulsion was characterized, and its bioavailability was examined in vitro (simulated gastrointestinal digestion) and in vivo. The mean size, PDI and zeta potential of the lutein nanoemulsion were 110 ± 8 nm, 0.271 and 36 ± 2 mV, respectively. Furthermore, TEM examination revealed that the particles are nanosized and spherical in shape. Notably, the aqueous solubility of the nanoemulsion was 726-fold higher than that of free lutein. The composite nanoemulsion also showed exceptionally higher (87.4%) in vitro bioaccessibility than that of nonencapsulated or free lutein (15%). The in vivo bioavailability of lutein nanoemulsion (112.6 ng/mL) was much higher than that of nonencapsulated lutein (48.6 ng/ml) and mixed micelles (68.5 ng/mL), and the tissue distribution pattern of lutein nanoemulsion showed higher lutein accumulation in the liver (2.80- and 1.70-fold) and eye (1.91- and 1.48-fold) compared to free lutein and mixed micelle-fed groups. These results suggested that oleic acid-linoleic acid composite nanoemulsions may be a promising delivery system for lutein and may help enhance the solubility, oral bioavailability and bioefficacy of lutein and could be used as an ingredient for the formulation of beverages or functional foods.