β‐sitosterol and gentisic acid loaded1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine liposomal particles

Abstract

The aim of the present study was the examination of the impact of β-sitosterol and gentisic acid on the characteristics of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine(DPPC) liposomal particles: (a) bilayer permeability (fluorescence spectroscopy),(b) particle size, polydispersity index (PDI) and zeta potential (photon correlation spectroscopy) and (c) thermal properties (differential scanning calorimetry).β-sitosterol induced the increase of liposomal bilayer rigidity, due to rearranging of the phospholipid chains, while gentisic acid enhanced the membrane fluidity, due to the reduced orderliness and the increase of phospholipid dynamics. The inclusion of β-sitosterol in liposomes caused a significant increase in particle diameter and PDI, while the encapsulation of gentisic acid did not have influence on particle size distribution. Apart from that, the presence ofβ-sitosterol resulted in the significant zeta potential increase, and thus a better stability of liposomal spheres(in the absence and in the presence of gentisic acid). β-sitosterol decreased main transition temperature (Tm) and phase transition enthalpy (∆H), and caused the disappearance of the pre-transition peak as well, whereas the presence of gentisic acid produced a slight decrease in Tm and increase of ∆H. Therefore, gentisic acid had more favourable, stabilizing interactions with phospholipids thanβ-sitosterol. Thus, it can be concluded that β-sitosterol is located in the bilayer interior between phospholipids acyl chains, and gentisic acid is incorporated near the outer leaflet of the phospholipid membrane, next to the polar head groups.β-sitosterol and gentisic acid loaded DPPC liposomal particles have a potential to be used in food and pharmaceutical products, due to the important individual and possible synergistic beneficial health properties ofβ-sitosterol and gentisic acid.