Chemical Stability and Skin Permeation of Fucoxanthin-Loaded Microemulsions

Abstract

Microemulsions (MEs) containing fucoxanthin in their oil (medium chain triglyceride) droplets were prepared using a mixture of Tween 80 and polyethylene glycol 400 as an emulsifier. The oil content was varied from 2 to 5 % and the fucoxanthin concentration from 0.1 to 0.25 %. The droplets were less than 500 nm on TEM photos. Fucoxanthin was chemically stable during the experimental period (1 month) when the MEs were stored at 2 and 25 °C under dark condition. However, it deteriorated rapidly and the reduction degree in its content was about 70 % in the same period when stored at 50 °C. In a 48-h in vitro skin permeation experiment, an appreciable amount of fucoxanthin (3 μg/cm 2 /h) was detected in the receptor solution of diffusion cells only when the oil content in the ME was the highest (e.g., 5 %), possibly because the chance of oil-soluble fucoxanthin interacting with the lipidic intercellular routes will be higher with higher oil content. The viscosity of MEs depended on neither the oil content nor the fucoxanthin concentration at 50 °C; however, it was proportional to both of them at 25 and 2 °C.