Encapsulated Anthocyanins from Sambucus peruviana and Vaccinium corymbosum in Chitosan-Alginate Nanoparticles for Potential Antidiabetic Applications

Abstract

Anthocyanins are natural pigments responsible for the red, blue, and purple colors in various fruits and vegetables. These compounds exhibit a wide range of biological activities, including antioxidant, anti-inflammatory, bactericidal, and, recently, antidiabetic activity. However, their application is limited due to their instability under pH changes, light exposure, oxygen, and temperature. To overcome these challenges, anthocyanins were extracted with ultrasound from Sambucus peruviana (elderberry) and Vaccinium corymbosum (blueberry) and then evaluated for enzymatic inhibition. The polysaccharides alginate and chitosan were used to encapsulate the extracts; the procedure involved the ionotropic gelation of alginate with calcium ions, followed by polyelectrolyte complexation with chitosan. The physicochemical stability of the resulting nanocapsules was evaluated based on particle size, polydispersity index (PDI), zeta potential, and UV–visible spectroscopy. The elderberry extract exhibited the highest total phenolic content (5.52 ± 0.66 μg gallic acid equivalents per mg of dry weight), whereas the blueberry extract contained a greater concentration of anthocyanins (2.69 ± 0.53 μg cyanidin-3-glucoside equivalents per mg of lyophilized product). Ethanolic extracts of both fruits demonstrated approximately twice the antioxidant capacity compared to their aqueous counterparts and exhibited notable inhibitory activity against lipase and α-amylase. The resulting nanoparticles displayed promising physicochemical properties, with average sizes of 515.03 ± 50.96 nm and 437.5 ± 12.59 nm for elderberry and blueberry extracts, respectively, low PDI values (0.31 ± 0.08 and 0.30 ± 0.03), and stable negative zeta potentials (−26.36 ± 2.00 mV and −27.45 ± 3.26 mV). These findings highlight the potential of ultrasound-assisted extraction and nanoencapsulation for enhancing anthocyanin stability and bioactivity, particularly for applications targeting enzyme inhibition associated with diabetes.