Enhanced bioaccessibility of pentacyclic triterpenes via interfacial engineering in W/O emulsions

The limited bioaccessibility of pentacyclic triterpenes remains a critical challenge in their practical application. To address this, our study developed novel self-constructed Pickering emulsions by self-assembled pentacyclic triterpene nanoparticles. FTIR analysis confirmed that pentacyclic triterpenes, including ursolic acid (UA), maslinic acid (MA), and betulinic acid (BA), self-assembled into nanoparticles within the oil phase driven by hydrogen bonding between their inherent hydroxy- and carboxyl- groups. Interfacial characterization demonstrated that these self-assembled nanoparticles absorbed onto the water/oil interface to stabilize emulsions. Quantitative analysis revealed distinct interfacial behaviors with MA nanoparticles exhibited the highest interfacial absorption capacity (>95.0%), and the lowest equilibrium interfacial tension (20.6 mN/m), followed by UA and BA nanoparticles. Crucially, in vitro simulated gastrointestinal digestion showed that interfacial delivered pentacyclic triterpenes in the resulting emulsions enhanced their bioaccessibility by over 20.0% compared to their free forms. Collectively, this work proposed interfacial engineering via pentacyclic triterpene self-assembly as a promising approach for improving their bioaccessibility.