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

The aim of the present study was the examination of the impact of -sitosterol andgentisic 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 correlationspectroscopy) and (c) thermal properties (differential scanning calorimetry). -sitosterol induced the increase of liposomal bilayer rigidity, due to rearranging ofthe phospholipid chains, while gentisic acid enhanced the membrane fluidity, dueto the reduced orderliness and the increase of phospholipid dynamics. The inclusionof -sitosterol in liposomes caused a significant increase in particle diameterand PDI, while the encapsulation of gentisic acid did not have influence on particlesize distribution. Apart from that, the presence of -sitosterol resulted in thesignificant zeta potential increase, and thus a better stability of liposomal spheres(in the absence and in the presence of gentisic acid). -sitosterol decreased maintransition temperature (Tm) and phase transition enthalpy (H), and caused thedisappearance of the pre-transition peak as well, whereas the presence of gentisicacid produced a slight decrease in Tm and increase of H. Therefore, gentisic acidhad more favourable, stabilizing interactions with phospholipids than -sitosterol.Thus, it can be concluded that -sitosterol is located in the bilayer interior betweenphospholipids acyl chains, and gentisic acid is incorporated near the outer leaflet ofthe phospholipid membrane, next to the polar head groups. -sitosterol and gentisicacid loaded DPPC liposomal particles have a potential to be used in food andpharmaceutical products, due to the important individual and possible synergisticbeneficial health properties of -sitosterol and gentisic acid.