Abstract

Balbisia peduncularis, also known as "Amancay", is a plant of the Ledocarpaceae family that can be found in the Atacama Desert in northern Chile. Infusions of the plant have long being used in traditional herbal medicine. Its chemical composition indicates the presence of flavonoids, which have antioxidant properties. Aqueous extracts from its stems were prepared to induce their interaction with human erythrocytes and their membrane models in order to elucidate whether this rare and unstudied plant produced perturbations to cell membranes. Scanning electron microscopy (SEM) of intact human red blood cells showed that the extract changed the normal erythrocytes morphology as a function of its concentration, first inducing echinocytes, and then stomatocytes and spherocytes. According to the bilayer couple hypothesis, the shape changes indicated that the flavonoids were first located in the outer monolayer of the erythrocyte membrane, and at the highest assayed concentration in both monolayers. The results obtained by fluorescence spectroscopy measurements of isolated unsealed human erythrocytes (IUM), of unilamellar vesicles (LUV) of dimyristoylphosphatidylcholine (DMPC), and by X-ray diffraction of DMPC and dimyristoylphosphatidylethanolamine (DMPE) multilayers, confirmed this conclusion. In fact, they showed that the plant aqueous extract molecules were located in both the hydrophilic polar head and in the hydrophobic acyl chain regions of the lipid bilayers. As a consequence, perturbations of the phospholipid bilayer packing arrangement were produced. © 2008 Elsevier Ireland Ltd. All rights reserved.