USE OF ANTIOXIDANTS DURING PREPARATION OF ALPHA-TOCOPHEROL ENRICHED LIPOSOMES

Ultrasonic radiation caused a breakdown in alpha-tocopherol in the liposomal membranes. Some of the radiolabelled 5-(CH3)-C-14-alpha-tocopherol had been broken to alpha-tocopherylquinone (18.7 +/- 1.57 %) and to a less polar compound of alpha-tocopherol (13.1 +/- 1.29 %). When alpha-tocopherol liposomes were incubated overnight the remaining alpha-tocopherol was 9.32 +/- 1.35 %. Use of butylated hydroxytoluene in liposomes or in the incubation medium (outside liposomes) improved recovery of alpha-tocopherol to some extent. Butylated hydroxytoluene in the liposomal fraction protected 26.8 +/- 1.78 % of alpha-tocopherol, while in the incubation medium (outside the liposome) it protected 37.9 +/- 1.18 %. There was a shift from alpha-tocopherylquinone formation to a less polar compound of alpha-tocopherol formation when butylated hydroxytoluene was present both in liposome and in the incubation medium; the protection was increased to 53.2 +/- 1.61 %. However, ascorbate added to the incubation medium protected 86.4 +/- 1.45 % of labeled alpha-tocopherol. Our findings suggest that ascorbate is a better antioxidant than butylated hydroxytoluene during the preparation of alpha-tocopherol liposomes.