The Effect of In Vitro Gastrointestinal Digestion on the Biological Activity of a Sea Cucumber (Holothuria forskali) Hydrolysate Encapsulated in Chitosan Nanoparticles and Rapeseed Lecithin Liposomes

A growing scientific interest in bioactive compounds from sea cucumbers is contributing to a broader recognition even in regions where their consumption is not common. This study evaluated the biological potential of a Holothuria forskali extract obtained through different extraction methods, including water extraction, ethanol–water extraction, and enzymatic hydrolysis. The hydrolysate (H), rich in low-molecular-weight peptides, yielded the highest antioxidant (30.6 ± 0.6 mg VitC Eq/g sample for ABTS and 10.7 ± 0.1 mg GAEs/g sample for Folin-reactive substances) and ACE-inhibitory (82.6%) activities. Based on these results, the hydrolysate was selected for encapsulation in two nanostructured delivery systems for comparative purposes: chitosan nanoparticles (NPs) and rapeseed lecithin liposomes (LPs). Both nanostructures were characterized in terms of size, ζ-potential, and polydispersity and subjected to simulated in vitro gastrointestinal digestion (GIDv) to assess their stability and mucoadhesive properties. After digestion, antioxidant activity increased in both systems, particularly in liposomes. Although encapsulation initially reduced ACE-inhibitory activity, gastrointestinal digestion restored or enhanced it, especially in liposomal formulations (≈37% inhibition). The mucoadhesive potential of the nanostructures after DGIv, focusing on their interactions with mucin, was assessed. Liposomal digests significantly increased viscosity in the presence of mucin, while chitosan nanoparticles decreased it, suggesting the formation of soluble complexes with reduced hydrodynamic volume. Electrostatic and hydrogen bonding interactions between chitosan and mucin were particularly evident in the NPH formulation. The rheological synergism parameter (Δη) revealed more negative values for NPs and NPHs, indicating stronger mucoadhesive interactions compared to controls and suggesting their suitability for mucosal delivery. These findings support the use of H. forskali hydrolysates as a source of functional bioactive compounds and highlight the potential of chitosan-based nanocarriers for enhancing their stability, bioaccessibility, and mucoadhesive properties in functional food or nutraceutical applications.