Development of a Sacha Inchi Oil-Based Nanoemulsion Containing Mangosteen Pericarp Extract and Its Antioxidant Activity

Background/Objectives: Mangosteen pericarp extract (Garcinia mangostana L.) exhibits robust antioxidant properties. However, its pharmaceutical application is hindered by poor water solubility and low physicochemical stability. This study aimed to develop a lipid-based nanoemulsion to overcome these limitations and assess its physicochemical characteristics, radical scavenging capacity, and dissolution profiles. Methods: Nanoemulsions were prepared by high-shear homogenization followed by ultrasonication method using sacha inchi oil (Plukenetia volubilis L.) across varying hydrophilic–lipophilic balance (HLB) values. Formulations were characterized by emulsion type, pH, rheology, droplet size, surface charge, encapsulation efficiency, and morphology via transmission electron microscopy. Antioxidant capacity was quantified using the DPPH assay, while in vitro dissolution experiments measured solubility enhancement relative to unformulated extract. Results: All formulations formed stable oil-in-water systems without phase separation. The HLB 10 formulation exhibited optimal performance, yielding a mean droplet diameter of 490.03 ± 32.12 nm, zeta potential of −52.73 ± 0.09 mV, and encapsulation efficiency of 89.14 ± 0.19%. Micrographs revealed well-structured spherical droplets. The raw extract showed strong antioxidant activity (IC50 = 21.68 ppm), which remained functional in nanoemulsion (IC50 = 84.48 ppm). Dissolution testing indicated a 13.4-fold improvement over raw powder. However, storage evaluation indicated chemical loss of bioactive constituents over one month. Conclusions: Sacha inchi oil-based nanoemulsions significantly enhance the dissolution rate of mangosteen pericarp extract while maintaining functional antioxidant potential. Although chemical stability during storage remains a limitation requiring further optimization, this nanocarrier platform offers strong potential to overcome solubility barriers for oral bioactive delivery.