Nanoencapsulation of α-mangostin using chitosan-oleic acid complexes: Evaluation of storage stability, in vitro release properties in simulated digestive environment, and bioaccessibility

Abstract

The mangosteen fruit possesses a potent antioxidant known as α-mangostin. However, the poor aqueous solubility of α-mangostin limits its incorporation into food products, as well as its oral bioaccessibility in the human gastrointestinal tract. Therefore, we utilized electrostatic complexation between chitosan and oleic acid to encapsulate α-mangostin as a strategy to overcome these limitations. As a result, a homogeneous nanoparticle suspension (average particle diameter = 830 nm) was achieved, as verified by scanning transmission electron microscopy and laser diffraction particle size analysis. Importantly, the aqueous solubility of α-mangostin was significantly improved (>800 times), as examined using high-performance liquid chromatography, enabling its effective incorporation into foods and beverages. The nanoparticles were stable and conveniently stored in a dark vial at 4 °C for more than 2 weeks. In the simulated gastric environment, the pH sensitivity of the chitosan-oleic acid complexes enabled the α-mangostin to remain encapsulated in the gastric phase (pH 3) and to be released in the intestinal phase (pH 7) with a bioaccessibility percentage greater than 50%. Overall, the novel synthesized α-mangostin-encapsulated nanoparticles are beneficial for the design of functional foods with enhanced quality, gastrointestinal stability, and delivery.