The Localization of Phenolic Compounds in Liposomal Bilayers and Their Effects on Surface Characteristics and Colloidal Stability

Abstract

The interactions with and effects of five chemically distinct, bioactive phenolic compounds on the lipid bilayers of model dipalmitoylphosphatidylcholine (DPPC) liposomes were investigated. Complementary analytical techniques, including differential scanning calorimetry (DSC) and phosphorus and proton nuclear magnetic resonance spectroscopy (NMR), were employed in order to determine the location of the compounds within the bilayer and to correlate location with their effects on bilayer characteristics and liposomal stability. As compared to the phenolic compounds localized in the glycerol region of the DPPC head group within the bilayer, which enhanced the colloidal stability of the liposomes, compounds located closer to the center of the bilayer reduced vesicle stability as a function of time. Molecules present in the upper region of liposomal DPPC acyl chains (C-C) inhibited liposomal aggregation and size increase, perhaps due to tighter packing of adjoining DPPC molecules and increased surface exposure of DPPC phosphate head groups. These data may be useful for designing liposomal systems containing hydrophobic phenols and other small molecules, selecting appropriate analytical methods for determining their location within liposomal bilayers, and predicting their effects on liposome characteristics early in the liposome formulation development process.

The Potential of Caffeic Acid Lipid Nanoparticulate Systems for Skin Application: In Vitro Assays to Assess Delivery and Antioxidant Effect

“…The peak position indicates a bilayer-tobilayer repeat distance of 6.90 nm. As found by other authors, the association of phenolic compounds to vesicular systems organized in bilayers can positively influence the bilayer organization [47].…”

“…The peak position indic layer-to-bilayer repeat distance of 6.90 nm. As found by other authors, the assoc phenolic compounds to vesicular systems organized in bilayers can positively i the bilayer organization [47]. Therefore, based on cryo-TEM and SAXS analysis results, SLN are characte a lipid tristearin matrix organized in lamellar structures dispersed in a poloxam ous phase, while the dispersed phase of ETHO is constituted of PC organized in mellar vesicles embedding water and ethanol.…”

Design and Characterization of Ethosomes for Transdermal Delivery of Caffeic Acid

“…The bilayer-to-bilayer repeat distance, derived from the peak positions and corresponding to the sum of the bilayer thickness plus the thickness of the water layer separating two adjacent bilayers, was 6.90 nm. It should be noted that other authors have found that the incorporation of hydrophobic phenolics into lipid vesicular systems bilayers could thoroughly affect the bilayer organization [44].…”

Odd Chain Phenolic Lipids in Liposomes as a Delivery System in Food using High Power Ultrasound

“…Liposomes can be used as artificial membranes to study the effects of compounds on these properties. This proposal suggests investigating the effect of phenolic lipids with varying chain length on cellular membrane properties using liposomes as an artificial model based on a previous study by (Malekar et al, 2015) that investigated phenolic compounds on liposomal membrane properties. Odd chain lipids should be investigated alongside to determine the effect of phenol rings.…”

“…Artificial liposomal membranes can be produced using phospholipids such as phosphocholine. Nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), dynamic light scattering (DLS), and zeta potential (ZP), conjugated dienes assay can be used as complementary analytical techniques to determine the location of compounds within the bilayer and their effect on bilayer characteristics and stability (Malekar et al, 2015). 1 H-NMR can help determine the structure of molecules by giving information on the number of protons and can offer insight into localization within the membrane with changes observed in samples vs the blank indicating presence of phenolic compounds near the head group of phosphocholine within the membrane bilayer.…”