Inhibitory effect of ebselen on the oxidation of low density lipoprotein

The inhibitory effect of a synthesized glutathione peroxidase (GSHPX) mimic- ebselen, and its cofactor glutathione (GSH), on the oxidation of low density lipoprotein (LDL) induced by Cu²⁺ was studied by determination of hydroperoxides and thiobarbituric acid reactive substances (TBARS). Ebselen alone had a strong inhibitory effect on the oxidation of LDL. The lag time of LDL oxidation was prolonged with an increase in the concentration of ebselen. The inhibitory effect of 5 μM ebselen was equivalent to that of 50 μM α-tocopherol. When GSH was present, ebselen exhibited stronger inhibitory effect than when present alone. With 50 μM GSH, ebselen at a concentration as low as 5 μM could inhibit oxidation of LDL induced by 5 μM Cu²⁺ completely for at least 24 h. Ebselen at high concentrations (100 μM) decomposed hydroperoxides in pre-oxidized LDL and effectively prevented its further oxidation, but not in the present of EDTA. Low concentration of ebselen (5 μM) plus GSH (50 μM) decomposed hydroperoxides in pre-oxidized LDL whether EDTA was added or not.