Tocopherols and Tocotrienols (Vitamin E)

Vitamin E consists of four tocopherols and four tocotrienols which have important and far-reaching biological activities. These essential lipids contain a common chromanol ring and either a saturated (tocopherol) or unsaturated (tocotrienol) side chain. The eight common vitamin E isoforms are α-, β-, γ-, and δ-tocopherol and α-, β-, γ-, and δ-tocotrienols. These isoforms are differentiated based on the number and position of methyl groups on the chromanol ring. The vitamin E vitamers are commonly found in vegetables, fruits, seeds, nuts, grains and oils where they exist in various ratios with each other. The unsaturated side chain in tocotrienols gives them physical properties different from tocopherols, such as an increased ability to cross the cell membrane bilayer. Vitamin E has become well known for its role as an antioxidant, in lowering levels of cholesterol and other lipids, as a neuroprotective and anti-cancer agent, and in cardiovascular disease protection. The tocotrienols in general may have greater physiological functions than tocopherols.(1,2)

References:

  1. K. Ahn et al. "γ-Tocotrienol Inhibits Nuclear Factor-κB Signaling Pathway through Inhibition of Receptor-interacting Protein and TAK1 Leading to Suppression of Antiapoptotic Gene Products and Potentiation of Apoptosis" J Biol Chem., Vol. 282 pp. 809-820, 2007
  2. R. Kannappan, et al. "γ-Tocotrienol but Not γ-Tocopherol Blocks STAT3 Cell Signaling Pathway through Induction of Protein-tyrosine Phosphatase SHP-1 and Sensitizes Tumor Cells to Chemotherapeutic Agents" J Biol Chem., Vol. 285 pp. 33520-33528, 2010