Liposomal and chitosan-coated liposomal nanocarriers for grape seed proanthocyanidins: Integrated physicochemical,...

Bioactive compounds derived from grape by-products support a circular economy approach and offer valuable opportunities for the nutraceutical and food industries. Among these by-products, grape seeds are of particular interest due to their high content of antioxidant proanthocyanidins (PAs). However, the aqueous solubility and chemical instability of PAs during processing, storage and consumption, limit their commercial viability. We hypothesize that an optimization in the PAs encapsulation would improve their physicochemical and biological performance, and the potential to be included in food formulations. In this study, we developed liposomes (Lip) as delivery systems for grape seed PAs and evaluated the effect of a chitosan (Cs) coating on their physicochemical properties, cellular responses, and rheological behavior. Both Lip and Cs/Lip formulations displayed high encapsulation efficiency (>90%) and presented particle sizes of 120-150 nm with low polydispersity. Storage studies demonstrated excellent colloidal stability, PAs retention, and antioxidant activity. Viability assays in Caco-2 and SH-SY5Y (neuroblastoma) cell lines confirmed the safety of the formulations and revealed increased viability at the highest tested concentrations (50 μg/mL in Caco-2: PAs-Lip increase 32% and PAs-Cs/Lip increase 24%; 1 μg/mL in SH-SY5Y: PAs-Lip increase 27% and PAs-Cs/Lip increase 40%). Notably, PAs encapsulation reduced the cytotoxic effects induced by the oxidant agent tert-butyl hydroperoxide, with Cs/Lip exhibiting the strongest protective activity. In summary, the developed formulations, due to their safety, stability, potential to increase cell viability, and rheological compatibility with aqueous-based formulations, represent interesting ingredients to be included in food products and convert them into functional foods.