From plant to nanomaterial: Physicochemical and functional characterization of nanochitosomes loaded with antioxidant peptide fractions from oleaster-seed protein

Abstract

In this study, bioactive peptides were derived from the hydrolysis of oleaster-seed proteins. Encapsulation of peptides within nanoliposomes (NLs) and nanochitosomes (NCs) structures would enhance their stability, bioavailability, and ability to improve peptide delivery. Protein hydrolysis using Alcalase significantly enhanced the antioxidant activity (2-3-fold increase across multiple indices) of peptide fractions (PFs), with the PF-10 kDa exhibiting the highest activity (DPPH⁻: 54.3 %, ABTS⁺: 89.5 %). This enhanced activity was attributed to increased free amino acids, enhanced hydrophobicity, and the presence of specific amino acids (lysine, arginine, histidine). The PFs-10 fraction was successfully loaded into NLs achieving a 75 % encapsulation efficiency. Chitosan coating further optimized loaded NLs characteristics, achieving a mean particle size of 195 nm, polydispersity index of 0.28, and a zeta potential of +41.5 mV, while maintaining high encapsulation efficiency (74.9 %). Chitosan coating significantly improved the stability of NLs against storage at 30 °C and freeze-thaw cycles, preserving both particle size and encapsulation efficiency better than uncoated NLs. FT-IR analysis confirmed the successful placement of peptides in the internal polar regions and monolayer membrane of liposomes. SEM analysis revealed the formation of ∼200–300 nm spherical NLs, while NCs exhibited aggregation at higher chitosan concentrations. The enhanced stability and bioactivity of oleaster-seed peptides, especially PF-10 kDa delivered via NLs and NCs demonstrate the potential of these nanocapsules as promising source of antioxidants. Overall, the findings of this study will effectively contribute to the development of innovative, solidified delivery systems with enhanced durability, functionality, and bioavailability ultimately leading to innovative and effective nutrition-based solutions.