Calcium-dependent aggregation and fusion of phosphatidylcholine liposomes induced by complexes of flavonoids with divalent iron

Abstract

It was found that complexes of the flavonoids quercetin, taxifolin, catechin and morin with divalent iron initiated an increase in light scattering in a suspension of unilamellar 100nm liposomes. The concentration of divalent iron in the suspension was 10μM. Liposomes were prepared from 1-palmitoyl-2-oleoylglycero-3-phoshpatidylcholine. The fluorescent resonance energy transfer (FRET) analysis of liposomes labeled with NBD-PE and lissamine rhodamine B dyes detected a slow lipid exchange in liposomes treated with flavonoid-iron complexes and calcium, while photon correlation spectroscopy and freeze-fracture electron microscopy revealed the aggregation and fusion of liposomes to yield gigantic vesicles. Such processes were not found in liposomes treated with phloretin because this flavonoid is unable to interact with iron. Rutin was also unable to initiate any marked changes because this water-soluble flavonoid cannot interact with the lipid bilayer. The experimental data and computer calculations of lipophilicity (cLogP) as well as the charge distribution on flavonoid-iron complexes indicate that the adhesion of liposomes is provided by an iron link between flavonoid molecules integrated in adjacent bilayers. It is supposed that calcium cations facilitate the aggregation and fusion of liposomes because they interact with the phosphate moieties of lipids.

Fusion between fluid liposomes and intact bacteria: study of driving parameters and in vitro bactericidal efficacy

“…[10][11][12] The divalent cations that induce interaction between negatively charged phospholipid vesicles have been studied extensively. [13][14][15] Negatively charged phospholipid vesicles do not naturally fuse or aggregate due to the long-range electrostatic repulsion. Divalent cations, by binding to negatively charged vesicles, reduce electrostatic repulsion, inducing aggregation shortly followed by fusion.…”

“…This is due to structural changes in bilayer vesicles resulting from the disruption of the strong repulsive hydration forces that prevent hydrophobic interaction between phospholipid bilayers at short distances of separation. [13][14][15] To understand further how these liposomes interact with bacteria, we investigated the factors involved in this process. In addition, the fluid liposomal-encapsulated tobramycin was later prepared, and the in vitro bactericidal efficacy of it to P. aeruginosa, Stenotrophomonas maltophilia, Burkholderia cepacia, Escherichia coli, and Staphylococcus aureus were also investigated.…”

Sustainable proliferation of liposomes compatible with inner RNA replication

“…We expected that the fusion of the RNA and nutrient liposomes would result in spontaneous fission due to the excess ratio of membrane area to volume (23). Liposome fusion has been achieved using many materials, such as polyethylene glycol (24), amphiphilic molecules (25), cationic ions (26,27), peptides (28), or lipid-anchored DNA oligonucleotides (29). However, because these systems require the addition of chemical compounds or peptides, the properties of the lipid membranes and/or biochemical reactions will change and may not maintain the same conditions after liposome fusion.…”

Flavonoid Complexes as Promising Anticancer Metallodrugs

“…Thus, after chelating the metal ion, the polarity of flavonoid molecules generally decreased, while the iron atom becomes the most polar and hence hydrophilic part of the molecule. Overall, the lipophilicity of the complexes is considerably larger than that of the corresponding free flavonoids [113,114].…”