Abstract
The purpose of this study was two-fold, 1) to extract and quantify vitamin E components from rice bran using microwave extraction, to determine the antioxidant activity of the rice bran oil, and the effect of solvent and temperature on vitamin E components and oil yield, and 2) to entrap alpha-tocopherol into polymeric nanoparticles, to characterize the nanoparticles in terms of morphology, size and size distribution, zeta potential, entrapment efficiency, and amount of residual PVA associated with the nanoparticles, as well as to study the release of alpha-tocopherol from PLGA nanoparticles.
Microwave-assisted extraction was an efficient method for the extraction of oil and vitamin E components from rice bran. Hexane was a better solvent for rice bran oil extraction as compared to isopropanol at 40ºC. At higher temperature, isopropanol was a better solvent for oil extraction. Hexane extracted large amount of α-tocotrienol at 120ºC while the increase in temperature for isopropanol was more beneficial for the extraction of γ-tocopherol. No significant differences in the oil yield, total vitamin E, and antioxidant activity of rice bran oil was noticed between the conventional solvent and microwave-assisted extractions, at 40ºC.
For the second part of the study, emulsion evaporation method was used to synthesize spherical PLGA(αT) nanoparticles with SDS and PVA as surfactants. For SDS nanoparticles, the size of the nanoparticles decreased significantly with the entrapment of α-tocopherol in the PLGA matrix, while the size of PVA nanoparticles remained unchanged. The PDI after synthesis was under 0.100 for PVA nanoparticles and around 0.150 for SDS nanoparticles. Zeta potential was negative for all PVA nanoparticles. The entrapment efficiency of α-tocopherol in the polymeric matrix was approximately 89% and 95% for nanoparticles with 8% and 16% α-tocopherol theoretical loading. The residual PVA associated to the nanoparticles after purification was approximately 6% (w/w relative to the nanoparticles). The release profile showed an initial burst followed by a slower release of the α-tocopherol entrapped inside the PLGA matrix. The release for nanoparticles with 8% α-tocopherol theoretical loading (86% released/first hour) was faster than the release for the nanoparticles with 16% α-tocopherol theoretical loading (34% released/first hour).
|
