Optimization, thermo-oxidative stability, and biological activities of vitamin E-chitosan–TPP nanoformulations

Abstract

Enhancing stability is a crucial factor in selecting bioactive compounds in most applications, while encapsulation techniques have proven to be a promising solution. Despite the critical applications of α-tocopherol (α-TQ) in the food and pharmaceutical industries, it is easily degraded by heat and oxidized by various oxidants in cells and foods; therefore, its more stable but less active acetate form (α-TQA) is commonly utilized. This study first optimized the preparation of the chitosan (CS) α-TQ nanoemulsion (α-TQ/CS–TPP/NE) using response surface methodology (RSM), achieving a minimum particle size of 278.1 nm; nanoparticles were also prepared and characterized by IR, TEM, and thermal analysis. Second, the chitosan nanoformulation exhibited greater thermal and oxidative stability against H₂O₂ and HOCl (>99%) than the precursors, α-TQ (68.62% and 22.22%) and α-TQA (86.86% and 26.44%), after 4 days. The nanoformulations also enhanced antioxidant activity against DPPH and hydroxyl radicals, as well as the reducing power, whereas α-TQA and its nanoparticles did not demonstrate antioxidant activity. Third, the kinetics of tocopherol release in different solvents were investigated and found to follow first-order kinetics, with diffusion as the main mechanism. Fourth, the nanoemulsion demonstrated effective applications in providing oxidative stability for edible oils at elevated temperatures, reducing oil oxidation by more than 85% upon heating at 100 °C for 5 hours. Fifth, α-TQ/CS–TPP/NE could enhance its anticancer activity against breast cancer (MCF-7). The increased thermo-oxidative stability, antioxidant activity, oil stabilization, and anticancer activity make α-TQ/CS–TPP/NE a valuable option as a dietary supplement or food additive.