Encapsulated Pterostilbene in pH-Sensitive Alginate Beads for LDL Oxidation Inhibition and Antioxidant Protection

Dietary intake of bioactive compounds from fruits and vegetables has been associated with a reduced risk of chronic diseases. Pterostilbene, a naturally occurring stilbenoid and dimethylated analogue of resveratrol, is abundant in blueberries and exhibits potent antioxidant and anti-inflammatory properties, highlighting its potential for cardiovascular applications. However, its clinical translation is limited by poor stability and low bioavailability. Here, pterostilbene was encapsulated in alginate-based microcapsules to protect the compound from premature degradation and enable controlled, pH-responsive release. The microcapsules were synthesized by ionic gelation and characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Encapsulation efficiency reached 95.6%. Antioxidant capacity was assessed in vitro using DPPH, ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) assays. The protective effect against oxidative stress was further evaluated by measuring the inhibition of Cu2+-induced human low-density lipoprotein (LDL) oxidation, followed by lipid peroxidation analysis using the TBARS assay. The microcapsules remained stable for up to 5 h under acidic conditions and fully dissolved within 1 h 38 min at basic pH. Encapsulation significantly enhanced the antioxidant activity of pterostilbene and improved its ability to inhibit LDL oxidation, supporting the potential of alginate-based delivery systems for cardiovascular applications.