Vitamin E supplement improves erythrocyte membrane fluidity of thalassemia: an ESR spin labeling study.

Background: β-thalassemia/Hemoglobin E (β-thal/Hb E) is prevalent in Thailand. The imbalance of globin chains in red blood cells is the primary cause of this anemic disease. The excess α-globin in β-thal/Hb E causes typical damage(s) to membrane of erythroblasts and erythrocytes. By using three paramagnetic labeled compounds (5-, 12-, and 16-spin labeled stearic acids, SLS), the changes of the molecular motion in the lipid bilayer of thalassemic RBCs that have structural modification can be detected. Objective: to investigate erythrocyte membrane fluidity and the effect of vitamin E treatment in β-thalassemia/Hemoglobin E patients by using spin labeling techniques. Material and Method: The erythrocyte membrane fluidity was investigated in nine splenectomized and five non-splenectomized β-thalassemia/hemoglobin E (β-thal/Hb E) patients using EPR spin labeling techniques. To determine the effect of vitamin E on erythrocyte membrane fluidity, only the splenectomized patients were enrolled. Patients were divided into two groups. The first group received 350 mg vitamin E daily for a period of 1 month (n = 5) and the second group received placebo for an equal period (n = 4). Three paramagnetic fatty acid, 5-, 12-, and 16-doxyl stearic acids, (5-, 12- and 16-DS) were used to label phospholipids layer near both the surface (5-DS) and the deeper hydrophobic region of membrane (12-and 16-DS). Lipid peroxidation (TBARs) was measured using a colorimetric method. Vitamin E was measured with high performance liquid chromatography (HPLC). Results: Significantly higher values of erythrocyte membrane fluidity were revealed with 12-, 16-DS in splenectomized patients, as compared with non-splenectomized patients and normal subjects. In β-thal/Hb E patients, fluidity values, both outer hyperfine splitting (2T//) and order parameter (S) of 12-DS showed inverse correlation with serum TBARs. There was no significant difference between the fluidity values measured with 5-DS. After vitamin E supplementation, the erythrocyte membrane fluidity was decreased in almost all patients. In contrast to the vitamin E supplementation group, increased erythrocyte membrane fluidity was demonstrated in the placebo group. Vitamin E supplementation also had effect on other clinical parameters such as increased plasma vitamin E, decreased serum TBARs and no change in hemoglobin. Conclusion: The present results suggested the abnormal motion of lipid in the deeper phospholipids region of membrane. In addition, vitamin E supplementation may have a role in the prevention of erythrocyte membrane damage of these patients. Keywords: Thalassemia, Membrane fluidity, Vitamin E, Spin labeling