Effects of four polyphenols loading on the attributes of lipid bilayers

The low bioavailability of polyphenol limits their use in functional foods. This study focused on the effects of luteolin, quercetin, proanthocyanidins, and apigenin loading on the attributes of lipid bilayers. Liposomes loaded with quercetin and proanthocyanidins were smaller in size and disperse more uniformly than those loaded with luteolin and apigenin. The spherical structures of these four liposomes were investigated via transmission electron microscope (TEM) and atomic force microscope (AFM). Raman spectra showed that the choline groups in all the liposome bilayers were mainly gauche conformations. Furthermore, polyphenolics had different effects on the liposomes' mobility and structure, which were dependent on the localization and orientation of polyphenolics in the lipid bilayer. X-ray diffraction (XRD) analysis indicates that four kinds of polyphenolics exist in an amorphous form in these liposomes. Fluorescence analysis indicates that the four polyphenolic compounds could load into the liposomes with different orientations. The ability of the four polyphenols to chelate Al3+ was significantly reduced in the lipid environment. The results reveal that polyphenolics' localization in lipid bilayers and their effects on lecithin membranes can be attributed to the polyphenols’ structural characteristics. These were vital factors that should be taken into account when designing a liposome delivery system. •Effects of polyphenol loading on attributes of lipid bilayers were investigated.•Four polyphenols were incorporated into lipid bilayer with different degrees.•Liposomes exhibited the strongest protective effect on proanthocyanidins.•The number of hydroxyl groups affects the interaction between phenols and liposomes.