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 α-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 µm 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.

 Keywords: alpha-tocopherol, vitamin E, calcium alginate, alginate particles, encapsulation

 Corresponding author:
Ana Barjaktarević
e-mail: ana.radovanovickg@gmail.com