Synthesis and Characterization of Alginate Microparticles for Oral Delivery of Alpha-Tocopherol

Introduction/Aim. Microencapsulation technology can be used for the protection of alpha-tocopherol from degradation in unfavorable environments and enhancement of bioavailability and shelf-life of vitamin E. The aim of this study was the synthesis and characterization of alginate microparticles for the oral delivery of alpha-tocopherol. Methods. Four different formulations of alpha-tocopherol loaded calcium alginate microparticles for oral delivery were synthesized by external ionotropic gelation method. The vitamin E content in microparticles was 0.5%, 1% and 2% (w/w); the vitamin E/sodium alginate ratio was 1:1 and 1:2. All microparticles were characterized by average particles size, swelling degree, vitamin E content, loading capacity, and encapsulation efficiency. Results. Spherically shaped microparticles with the diameter of 500 to 1000 mu m were obtained after the drying process. The size and the swelling degree did not change significantly in 0.1 M HCL, while they were increased in base conditions of phosphate buffer of pH 6.8 and 7.4. Encapsulated vitamin E content was not significantly different between formulations (0.30 +/- 0.010 - 0.60 +/- 0.021 mg/mL). The loading capacities were in the range between 10 +/- 0.11% and 20.45 +/- 0.22%, while encapsulation efficiency percentages were between 18.94 +/- 0.32% and 31.91 +/- 0.41%. Conclusion. The optimum conditions for alpha-tocopherol encapsulation with the highest percentage of loading capacity and encapsulation efficacy were obtained using 1% sodium alginate, 2% calcium chloride, and vitamin E/polymer in the ratio 1:1. All four formulations showed the expected behavior in different mediums, which simulated gastrointestinal fluids in vivo (0.1 M HCL, phosphate buffer pH 6.8 and pH 7.4): gastroresistance, increasing in the size, and swelling degree in intestinal fluids. This emphasizes the use of alginate microparticles as a carrier for the oral delivery of vitamin E.