Antioxidant Activity of Lutein Entrapped in Poly (DL-Lactide Co-Glycolide) Acid and PLGA/Chitosan Nanoparticles

Abstract

Polymeric nanocarriers improve cellular uptake, stability, solubility, and functionality of entrapped drugs and nutraceuticals. The hypothesis of this study was that entrapping lutein, a hydrophobic antioxidant, in different polymeric nanoparticles (NPs) will improve its stability and antioxidant activity. The following objectives were proposed: 1. Synthesize and characterize polymeric nanoparticles of poly lactic co-glycolic acid (PLGA) and PLGA NPs covered with a layer of chitosan (PLGA/Chi) from a physicochemical perspective, and 2. Assess functionality of the entrapped lutein as a function of type of polymer in which entrapped. Nanoparticles were synthesized by emulsion evaporation method. Characterization included size, zeta potential, and morphology measurement, followed by testing the physical and chemical stability, and antioxidant activity of entrapped lutein. PLGA NPs loaded with lutein were in the size range of 119.2 nm ± 0.98 nm with a PDI of 0.17± 0.02 and a zeta potential of – 29 mV ± 1.1 mV in nanopure water with 0.05 mg PVA/ mg PLGA ± 0.002 mg PVA/ mg PLGA remaining on the surface of the nanoparticles. PLGA/Chi NPs loaded with lutein were in the size range of 145.9 ± 0.3 nm with a PDI of 0.25 ± 00.01 and a zeta potential of 21.2 mV ± 2.3 mV with 0.06 mg ± 0.002 mg PVA/ mg PLGA/Chi remaining in nanopure water. PLGA NPs and PLGA/Chitosan NPs loaded with lutein were stable in emulsions made with Tween 20 for 72 hours at 37 °C as indicated by a constant size over time. PLGA and PLGA/Chi NPs protected the chemical stability of lutein in Tween 20 emulsions for 24 hours at 37 °C. PLGA and PLGA/Chitosan NPs showed significant reductions in the oxidation of cholesterol by 45 ± 1% and 60 ± 1 % at 48 hours, and 36 ± 1 % and 42 ± 3 % at 72 hours when compared to the free lutein. The addition of chitosan to the PLGA NPs further enhanced the efficacy of lutein as an antioxidant when compared to PLGA NPs. These results support the hypothesis that polymeric NPs are enhancing stability and antioxidant activity of entrapped lutein and hence may find beneficial applications in the biomedical and food science fields for delivery of lutein.