Development and characterization of a novel naturally occurring pentacyclic triterpene self-stabilized pickering emulsion

Abstract

Phytochemicals self-stabilized Pickering emulsion is expected to be a highly desirable oral self-delivery system. In this study, ursolic acid (UA), a representative pentacyclic triterpene, was reported for the first time that can be formed self-stabilized Pickering emulsion. That is, it is experimentally and theoretically proved that water-in-oil Pickering emulsion could be stabilized solely by UA. First, the morphology, wettability and interfacial properties of the UA particles were characterized. Then, the influence of variation with UA particle concentration (c) and water fraction (ϕ) on the droplet size and coalescence (and sedimentation) stability of UA stabilized emulsions were also studied. It was found that the formed emulsions performed excellent sediment stability except that under conditions where the UA particle concentration is low (c=1 wt%) or at low water fraction(ϕ=0.1). The viscoelastic properties of the emulsions could be improved with the increasing c or ϕ. Finally, The molecular dynamics simulation further verified that the UA particles are located at the oil-water interface and incompletely wrapped the water droplets to form a stable W/O Pickering emulsion. This work enriches the family of sustainable W/O Pickering stabilizers and provides a new strategy for the construction of a Carrier-Free Delivery System for pentacyclic triterpenes.