Tocotrienols In Free Radical Scavenging And Antioxidant Activity

TRF has excellent free radical scavenging capacity (Kamat et al., 1997). Numerous studies (Ikeda et al., 2003; Kamat et al., 1997) show that it is a potent inhibitor of lipid peroxidation and protein peroxidation in rat microsomes and mitochondria. At low concentrations of 5 mM, TRF, mainly g-tocotrienol and to a lesser extent a- and d-tocotrienols, significantly inhibited oxidative damage to both lipids and proteins in rat brain mitochondria. Studies of the effect of g-tocotrienols on endothelial nitric oxide synthase (eNOS) activity in spontaneously hypertensive rats have reported that on treatment with antioxidant g-tocotrienol increased the nitric oxide (NO) activity and concomitantly reduced the blood pressure and enhanced total antioxidant status in plasma and blood vessels (Ikeda et al., 2003). In general, TRF has significantly higher antioxidant ability as compared to tocopherols. This can be explained by the structural difference between the saturated side chain of tocopherols and the unsaturated side chain of toco-trienols. The molecular mobility of polyenoic lipids in the membrane bilayer (composed mainly of unsaturated fatty acid) is much higher than that of saturated lipids, and hence tocotrienols are more mobile and less restricted in their interaction with lipid radicals in membranes than tocopherols.

This is further supported by the higher effectiveness of tocotrienols in processes that may involve oxidative stress such as in red blood cells where tocotrienols have more potency against oxidative hemolysis than «-tocopherols (Kamat et al., 1997). In an in vitro study, the potent free radical scavenging property of «-tocopherol was found 1600 times more as compared to free radical scavenging property of «-tocotrienols (Serbinova and Packer, 1994). In another study, it was found the potent antioxidative property of g-tocotrienols significantly protect the spontaneously hypertensive rats (Newaz et al., 2003).

0 0

Post a comment