A METHOD FOR SIMULTANEOUS DETERMINATION OF PLASMA AND ERYTHROCYTE ANTIOXIDANT STATUS - EVALUATION OF THE ANTIOXIDANT ACTIVITY OF VITAMIN-E IN HEALTHY-VOLUNTEERS

1 Since oxygen free radicals are directly involved in a variety of pat hologies such as atherosclerosis, diabetes mellitus, inflammation and/ or when a deficit of defences of the organism against radicals occurs, we developed a suitable and simple method to determine both the eryth rocyte sensitivity to an oxidative stress and plasma antioxidant prote ctive capacity. 2 This test is based on the introduction at 37 degrees C of a radical initiator, 2,2'-azobis (2-amidinopropane) dihydrochlor ide (AAPH), within an erythrocyte suspension leading to a membrane alt eration and ultimately to haemolysis. The latter can be quantified by determining the lacticodeshydrogenase activity released in the medium. The erythrocyte sensitivity to haemolysis and the volume of plasma in hibiting 50% of the haemolysis were determined. 3 Intra-assay CVs were 1.9% for erythrocyte sensitivity to oxidative stress and 3.4% for inh ibitory 50% plasma volume. Inter-assay CVs for both erythrocyte sensit ivity and inhibitory 50% plasma volume were 4%. 4 The reliability of t his method was assessed and applied to test the protective effect of v itamin E, a well known antioxidant agent, in six healthy volunteers. T wo weeks after daily administration of 500 mg of vitamin E, the mean p lasma vitamin E concentration increased by 41% from 10.7 +/- 2.0 mg l( -1) before treatment (P<0.05). As the vitamin E concentration increase d,the mean inhibitory 50% plasma volume and the percentage of haemolys ed erythrocytes decreased respectively by 29% from 3.35 +/- 0.5 mu l ( P<0.05) and 18% from 71.5 +/- 3.8% (P < 0.05). No significative variat ion of these parameters was observed in six adult men without vitamin E supplementation. 5 Thus, this global and simple test permits an anti oxidant status evaluation of a patient. It can be applied to various p athologies and allows the potency of new antioxidant molecules to be e valuated.