Improving the bioaccessibility and bioavailability of carnosic acid using nanoemulsion: complementary in vitro and in vivo studies
Carnosic acid (CA) represents one of the most effective antioxidants that can be applied for the prevention of degenerative and chronic diseases. However, the intrinsic hydrophobic nature of CA results in low solubility and poor dissolution in the gastrointestinal (GI) tract, which limits its applications in a variety of functional food systems. In order to address these issues, we encapsulated CA in lecithin-based nanoemulsion (CA-NE) to improve its bioaccessibility and bioavailability which are evaluated using in vitro and in vivo digestion model. The CA-NE demonstrated a loading capacity of 2.6-3.0 %, an average particle size of 165 nm, ζ-potential value of -57.2 mV, and good stability during 4-week storage at 4, 25, and 37 °C. The in vitro static pH-stat lipolysis and dynamic TNO’s gastrointestinal (TIM-1) model demonstrated a 12.6 and 5.6 fold increase in the total bioaccessibility for CA encapsulated in nanoemulsion, respectively, as opposed to CA in suspension form. Moreover, the in vivo pharmacokinetic study on rat model (Male Sprague Dawley) confirmed that the bioavailability of CA in nanoemulsion was a 2.2 fold increase, as compared to that of CA in suspension form. In conclusion, the bioaccessibility and bioavailability of CA were remarkably improved by encapsulation of CA in lecithin-based nanoemulsion. Moreover, the combined in vitro and in vivo study could be used as a useful approach for the comprehensive evaluation of oral lipid-based delivery systems.