Propolis-Based Nanostructured Lipid Carriers for alpha-Mangostin Delivery: Formulation, Characterization, and In Vitro Antioxidant Activity Evaluation

alpha-Mangostin (a xanthone derivative found in the pericarp of Garcinia mangostana L.) and propolis extract (which is rich in flavonoids and phenols) are known for their antioxidant properties, making them potential supplements for the treatment of oxidative stress-related conditions. However, these two potential substances have the same primary drawback, which is low solubility in water. The low water solubility of alpha-mangostin and propolis can be overcome by utilizing nanotechnology approaches. In this study, a propolis-based nanostructured lipid carrier (NLC) system was formulated to enhance the delivery of alpha-mangostin. The aim of this study was to characterize the formulation and investigate its influence on the antioxidant activity of alpha-mangostin. The results showed that both unloaded propolis-based NLC (NLC-P) and alpha-mangostin-loaded propolis-based NLC (NLC-P-alpha-M) had nanoscale particle sizes (72.7 +/- 1.082 nm and 80.3 +/- 1.015 nm, respectively), neutral surface zeta potential (ranging between +10 mV and -10 mV), and good particle size distribution (indicated by a polydispersity index of <0.3). The NLC-P-alpha-M exhibited good entrapment efficiency of 87.972 +/- 0.246%. Dissolution testing indicated a similar to 13-fold increase in the solubility of alpha-mangostin compared to alpha-mangostin powder alone. The incorporation into the propolis-based NLC system correlated well with the enhanced antioxidant activity of alpha-mangostin (p < 0.01) compared to NLC-P and alpha-mangostin alone. Therefore, the modification of the delivery system by incorporating alpha-mangostin into the propolis-based NLC overcomes the physicochemical challenges of alpha-mangostin while enhancing its antioxidant effectiveness.