Effect of gentisic acid on the structural-functional properties of liposomes incorporating beta-sitosterol

Abstract

Multifunctional liposomes incorporating beta-sitosterol were developed for delivery of gentisic acid (GA). The interactions of both compounds with phospholipid bilayer were interpreted viaeffects of different beta-sitosterol content (0, 20 and 50 mol %) and different gentisic acid to lipid ratio (n(GA)/n(lip) from 10(-5) to 1) on membrane fluidity and thermotropic properties. Multilamellar vesicles of phosphatidylcholines (with size range between 1350 and 1900 nm) effectively encapsulated GA (54%) when n(GA)/n(lip) was higher than 0.01. Suppression of lipid peroxidation was directly related to concentration of GA. The resistance to diffusion of gentisic acid from liposomes increased for (similar to)50% in samples incorporating 50 mol % beta-sitosterol compared to sterol-free liposomes. Finally, simulated in vitro gastrointestinal conditions showed that the release was mainly affected by low pH of simulated gastric fluid and the presence of cholates in simulated intestinal fluid, rather than by enzymes activity.