Enhancing oral bioavailability using preparations of apigenin-loaded W/O/W emulsions: In vitro and in vivo evaluations

• Physical properties and digestibility of apigenin-loaded emulsions were investigated.
• Well-shaped spherical W/O/W emulsions were obtained regardless of composition.
• Soybean oil-Tween 80 emulsions showed the highest stability during digestion.
• Preparation of W/O/W emulsions could enhance the oral bioavailability of apigenin.

We analyzed the physical properties and digestibility of apigenin-loaded emulsions as they passed through a simulated digestion model. As the emulsion passed through the simulated stages of digestion, the particle size and zeta potential of all the samples changed, except for the soybean oil-Tween 80 emulsion, in which zeta potential remained constant, through all stages, indicating that soybean oil-Tween 80 emulsions may have an effect on stability during all stages of digestion. Fluorescence microscopy was used to observe the morphology of the emulsions at each step. The in vivo pharmacokinetics revealed that apigenin-loaded soybean oil-Tween 80 emulsions had a higher oral bioavailability than did the orally administrated apigenin suspensions. These results suggest that W/O/W multiple emulsions formulated with soybean oil and tween 80 have great potential as targeted delivery systems for apigenin, and may enhance in vitro and in vivo bioavailability when they pass through the digestive tract.