In vitro antioxidant activity of liposomal formulations of sea buckthorn and grape pomace

Abstract

This study evaluated the impact of the encapsulation of sea buckthorn and grape pomace extracts in liposomal formulations on the retention and release of bioactive compounds and their antioxidant activity. The profile and composition of lipophilic extracts of sea buckthorn and hydrophilic extracts of grape pomace were analyzed. Encapsulation efficiency, retention rate, and the content of bioactive compounds encapsulated in liposomal formulations prepared in two media—water and ethanol—were evaluated. The encapsulation efficiency varied between 84 and 90%, indicating the superior encapsulation of the bioactive compounds. The retention rate varied between 79 and 86%, which indicated the stability of the liposome-encapsulated compounds over time. The antioxidant activity of the encapsulated samples was determined in vitro, under the conditions of gastric (pH 1.8) and intestinal (pH 8.2) digestion, in relation to the non-encapsulated extracts. The antioxidant activity of both liposomal formulations was higher than that of the nonencapsulated extracts during gastric digestion. Moreover, an increase over time in the antioxidant activity, expressed as % DPPH inhibition, was observed for all samples, with around 90% DPPH inhibition for non-encapsulated extracts and 92% for the encapsulated extracts, demonstrating the stability of bioactive compounds in acidic pH. Oppositely, when exposed to intestinal simulated digestion (alkaline pH), the antioxidant activity decreased over time to around 24% DPPH inhibition for both encapsulated and nonencapsulated extracts. These results provide a foundation for the further development and application of liposomal delivery systems in functional foods.