‐sitosterol and gentisic acid loaded 1,2‐dipalmitoyl‐sn‐glycero‐3‐phosphocholine liposomal particles

Abstract

The aim of the present study was the examination of the impact of -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). -
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 -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 of -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). -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 than -sitosterol.
Thus, it can be concluded that -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. -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 of -sitosterol and gentisic acid.