Abstract

Ugni molinae Turcz, also known as "Murtilla", is a plant that grows in the south of Chile. Infusions of its leaves have long been used in traditional native herbal medicine. The chemical composition of the leaves indicates the presence of polyphenols, which have antioxidant properties. In the present work, the antioxidant properties of U. molinae were evaluated in human erythrocytes exposed in vitro to oxidative stress induced by HClO. The experiments were carried out by scanning electron microscopy (SEM) and hemolysis measurements. The SEM observations showed that HClO induced a morphological alteration in the red blood cells from a discoid to an echinocytic form. According to the bilayer couple hypothesis, the formation of echinocytes indicates that HClO was inserted in the outer leaflet of the erythrocyte membrane. However, a concentration as low as 10 μM gallic acid equivalents (GAE) U. molinae aqueous extract neutralized the shape change effect of HClO applied in a concentration as high as 0.25 mM. The significant protection of U. molinae aqueous extract was also shown in the hemolysis experiments. In fact, very low concentrations of the extract considerably reduced the deleterious capacity of HClO to induce hemolysis in red blood cells. It is concluded that the location of the extract components into the membrane bilayer and the resulting restriction on its fluidity might hinder the diffusion of HClO and its consequent damaging effects. This conclusion can also imply that this restriction could apply to the diffusion of free radicals into cell membranes and the subsequent decrease of the kinetics of free radical reactions. © 2006 Elsevier Ltd. All rights reserved.