Gamma-Tocotrienol: Potential as a Countermeasure against Radiological Threat

Tocotrienols exist in nature as four tocol isoforms of the vitamin E family — α, β, γ and δ tocotrienols. Among them, gamma (γ)-tocotrienol (GT3), a better antioxidant than alpha-tocopherol (AT, also commonly known as vitamin E), has gained importance due to its potent inhibition of hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase enzyme. GT3 has almost 30-fold greater inhibitory activity than alpha-tocotrienol. HMG-CoA reductase is the pivotal enzyme in the synthesis of mevalonic acid, a key metabolic intermediate in the biosynthetic pathway of cholesterol. Regulation of this enzyme has been the basis for developing cholesterol-lowering drugs-statins-for nearly two decades (Pearce et al., 1992).