Interaction of selected anthocyanins with erythrocytes and liposome membranes

Anthocyanins are one of the main flavonoid groups. They are responsible for, e.g., the color of plants and have antioxidant features and a wide spectrum of medical activity. The subject of the study was the following compounds that belong to the anthocyanins and which can be found, e.g., in strawberries and chokeberries: callistephin chloride (pelargonidin-3-O-glucoside chloride) and ideain chloride (cyanidin-3-O-galactoside chloride). The aim of the study was to determine the compounds’ antioxidant activity towards the erythrocyte membrane and changes incurred by the tested anthocyanins in the lipid phase of the erythrocyte membrane, in liposomes composed of erythrocyte lipids and in DPPC, DPPC/cholesterol and egg lecithin liposomes. In particular, we studied the effect of the two selected anthocyanins on red blood cell morphology, on packing order in the lipid hydrophilic phase, on fluidity of the hydrophobic phase, as well as on the temperature of phase transition in DPPC and DPPC/cholesterol liposomes. Fluorimetry with the Laurdan and Prodan probes indicated increased packing density in the hydrophilic phase of the membrane in the presence of anthocyanins. Using the fluorescence probes DPH and TMA-DPH, no effect was noted inside the hydrophobic phase of the membrane, as the lipid bilayer fluidity was not modified. The compounds slightly lowered the phase transition temperature of phosphatidylcholine liposomes. The study has shown that both anthocyanins are incorporated into the outer region of the erythrocyte membrane, affecting its shape and lipid packing order, which is reflected in the increasing number of echinocytes. The investigation proved that the compounds penetrate only the outer part of the external lipid layer of liposomes composed of erythrocyte lipids, DPPC, DPPC/cholesterol and egg lecithin lipids, changing its packing order. Fluorimetry studies with DPH-PA proved that the tested anthocyanins are very effective antioxidants. The antioxidant activity of the compounds was comparable with the activity of Trolox®.

Odd-numbered long-chain fatty acids in erythrocyte phospholipids as long-term follow-up parameter in propionic acidemia

Odd-numbered long-chain fatty acids (OLCFAs) increase in total erythrocyte lipids or plasma in patients with propionic acidemia and have been proposed as a useful parameter of metabolic control. However, up to now no parameter for long-term metabolic control has been available for this disorder. In contrast to previous investigations, we investigated OLCFAs with particular reference to differences for two phospholipid fractions of erythrocyte lipids. The phosphatidylethanolamine (PE) fraction of erythrocyte lipids has a slow turnover rate and might reflect the metabolic propionyl-CoA burden over a period of some weeks. Distinct increases in OLCFA of up to 200% in the phosphatidylcholine fraction were observed after episodes of metabolic decompensation and maximum OLCFA levels were found 3 weeks after the onset of a crisis. As a sign of poor metabolic control, OLCFA levels in PE steadily increased after recurrent episodes of decompensation, but not in clinically stable patients. However, in one patient with clinically good metabolic control, OLCFAs continually increased after the second year of life for an as yet unknown reason. In conclusion, data from this study indicate the usefulness of OLCFA analysis in the PE fraction of erythrocyte lipids, in particular with regard to the need for such a parameter for evidence-based improvement of management strategies in propionic acidemia.