An effective strategy to improve the bioaccessibility of oleanolic acid in self-constructed water-in-oil emulsions: oil phase gelation based on octacosanol

Self-constructed W/O emulsions were used as effective oral delivery systems for triterpenoids. Whether stabilization by gelation of the oil phase can improve the delivery of emulsions needs further investigation. In this work, we used the bioactive substance (Octacosanol, Octa) as the oil gelator and the typical triterpenoid (Oleanolic acid, OA) as the stabilizer to prepare the water-in-oleogel emulsion delivery system. Results demonstrated that increasing Octa concentration induced the formation of a denser needle-like crystal network within the oleogel, accompanied by enhancing thermal stability and excellent storage stability of the emulsion. Furthermore, the gelator concentration can be modulated to gel properties. Following Octa-induced oil phase gelation, droplets in the water-in-oleogel emulsion system exhibited reduced particle sizes upon entering the simulated intestinal fluid phase, accompanied by a higher lipid digestion degree, accelerated digestion rate, and increased OA bioaccessibility. This study not only advances food-grade solutions for OA oral delivery but also offers a paradigm for constructing simplified delivery systems that leverage intrinsic bioactive properties to minimize exogenous additives.