Effect of nano-delivery systems on the bioavailability and tissue biodistribution of vitamin E tocotrienols

Abstract

Vitamin E is one of the most important essential vitamins to support the regulation of oxidative stress in human body. Tocotrienols are part of the vitamin E family. The potentials of tocotrienols as nutraceutical ingredient are largely understated due to low oral bioavailability, which is a common problem associated with fat-soluble bioactive compounds. Nanoencapsulation technology offers innovative solutions to enhance the delivery mechanisms of these compounds. In this study, the effect of nanoencapsulation on the oral bioavailability and tissue distribution of tocotrienols were investigated using two types of formulations, i.e. nanovesicles (NV-T3) and solid lipid nanoparticles (NP-T3). At least 5-fold increment in maximum plasma concentrations, evident with dual-peak pharmacokinetic profiles, were observed after oral administration of nano-encapsulated tocotrienols. Plasma tocotrienol composition showed a shift from α-tocotrienol dominant in control group (Control-T3) to γ-tocotrienol dominant after nanoencapsulation. Tissue distribution of tocotrienols was found to be strongly influenced by the type of nanoformulation. Both nanovesicles (NV-T3) and nanoparticles (NP-T3) showed elevated accumulation in the kidneys and liver (5-fold) compared to control group while selectivity for α-tocotrienol was evident for NP-T3. In brain and liver of rats given NP-T3, α-tocotrienol emerged as the dominant congener (>80%). Acute oral administration of nanoencapsulated tocotrienols did not show signs of toxicity. The study concluded enhanced bioavailability and selective tissue accumulation of tocotrienol congeners when delivered via nanoencapsulation.

Keywords: Absorption; Bioavailability; Biodistribution; Nanoparticles; Nanovesicles; Tocotrienols; Vitamin E.