Nanoencapsulation of Rice Bran Oil to Enhance Its UV-Protective Effects

Abstract

Background: Rice bran and its bioactive constituents have long been recognized for their therapeutic potential. Solid lipid nanoparticles (SLNs) have emerged as promising delivery systems for bioactive compounds because of their nanoscale dimensions and favorable physicochemical properties. Objectives: This study aimed to develop rice bran oil (RBO)-loaded SLNs and evaluate their physicochemical characteristics, release behavior, and photoprotective potential. Methods: RBO-loaded SLNs were prepared by emulsification followed by ultrasonic homogenization. Particle size, zeta potential, encapsulation efficiency (EE), and in vitro release were determined. Nanoparticle morphology was evaluated by transmission electron microscopy. The UV-protective activity of RBO and rice bran oil-loaded solid lipid nanoparticles (RBO-SLNs) against UVA, UVB, and UVC radiation was assessed by UV spectrophotometry. Results: The optimized RBO-SLNs had a mean particle size of 23.53 nm and a zeta potential of −48.1 mV. The EE of RBO was 85%, and cumulative release reached 39.24% after 72 h. Incorporation of RBO into SLNs significantly enhanced UV-absorbing capacity, particularly against UVB and UVC radiation, compared with free oil. Conclusions: RBO-SLNs demonstrated favorable physicochemical characteristics, efficient oil encapsulation, and sustained release. Their enhanced UVB- and UVC-protective activity highlights their potential for incorporation into skin-care and photoprotective formulations. Further ex vivo and in vivo studies are required to validate their efficacy and safety.