TOCOTRIENOLS FROM PALM OIL AS EFFECTIVE INHIBITORS OF PROTEIN OXIDATION AND LIPID-PEROXIDATION IN RAT-LIVER MICROSOMES

Tocotrienols from palm oil showed significant ability to inhibit oxida tive damage induced by ascorbate-Fe2+ and photosensitization, involvin g different mechanisms, in rat liver microsomes. The tocotrienol-rich fraction from palm oil (TRF), being tried as a more economical and eff icient substitute for alpha-tocopherol, showed time- and concentration -dependent inhibition of protein oxidation as well as lipid peroxidati on. It was more effective against protein oxidation. The extent of inh ibition by TRF varied with different peroxidation products such as con jugated dienes, lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS). Among the constituents of TRF, gamma-tocotrienol w as the most effective followed by its alpha- and delta-isomers. In gen eral, at a low concentration of 5 mu M, TRF was able to prevent oxidat ive damage to significant extent (37% inhibition of protein oxidation and 27-30% of lipid peroxidation at 1 h of incubation). The protective ability of TRF (30.1% at 5 mu M with TBARS formation) was significant ly higher than that of the dominant form of vitamin E, alpha-tocophero l (16.5% under same conditions). Hence our studies indicate that this fraction from palm oil can be considered as an effective natural antio xidant supplement capable of protecting cellular membranes against oxi dative damage.