Tocotrienol

Not to be confused with the more common class of molecules that are also forms of vitamin E, the tocopherols.
General chemical structure of tocotrienols. alpha(α)-Tocotrienol: R1 = Me, R2 = Me, R3 = Me; beta(β)-Tocotrienol: R1 = Me, R2 = H, R3= Me; gamma(γ)-Tocotrienol: R1 = H, R2 = Me, R3= Me; delta(δ)-Tocotrienol: R1 = H, R2 = H, R3= Me

The vitamin E family comprises four tocotrienols (alpha, beta, gamma, delta) and four tocopherols (alpha, beta, gamma, delta). The critical chemical structural difference between tocotrienols and tocopherols is that tocotrienols have unsaturated isoprenoid side chains with three carbon-carbon double bonds versus saturated side chains for tocopherols (see Figure).[1][2]

Tocotrienols are compounds naturally occurring at higher levels in some vegetable oils, including palm oil, rice bran oil, wheat germ, barley, saw palmetto, annatto, and certain other types of seeds, nuts and grains, and the oils derived from them.[3][4]

Chemically, different analogues of vitamin E all show some activity as a chemical antioxidant,[5] but do not all have the same vitamin E equivalence. Tocotrienols demonstrate activity depending on the type of antioxidant performance being measured.[6] All tocotrienols have some physical antioxidant activity due to an ability to donate a hydrogen atom (a proton plus electron) from the hydroxyl group on the chromanol ring, to free radical and reactive oxygen species. Historically studies of tocotrienols account for less than 1% of all research into vitamin E.[7] Tocotrienols are generally well tolerated and without significant side effects.

  1. ^ Kamal-Eldin A, Appelqvist LA (July 1996). "The chemistry and antioxidant properties of tocopherols and tocotrienols". Lipids. 31 (7): 671–701. doi:10.1007/BF02522884. PMID 8827691. S2CID 4052785.
  2. ^ Clarke MW, Burnett JR, Croft KD (2008). "Vitamin E in human health and disease". Critical Reviews in Clinical Laboratory Sciences. 45 (5): 417–50. doi:10.1080/10408360802118625. PMID 18712629. S2CID 85991655.
  3. ^ Tan B, Watson RR, Preedy VR, eds. (2013). Tocotrienols: Vitamin E Beyond Tocopherols (2nd ed.). Boca Raton: CRC Press. ISBN 9781439884416.
  4. ^ Sen CK, Rink C, Khanna S (June 2010). "Palm oil-derived natural vitamin E alpha-tocotrienol in brain health and disease". Journal of the American College of Nutrition. 29 (3 Suppl): 314S–323S. doi:10.1080/07315724.2010.10719846. PMC 3065441. PMID 20823491.
  5. ^ Cerecetto H, López GV (March 2007). "Antioxidants derived from vitamin E: an overview". Mini Reviews in Medicinal Chemistry. 7 (3): 315–38. doi:10.2174/138955707780059871. PMID 17346221.
  6. ^ Fu JY, Che HL, Tan DM, Teng KT (January 2014). "Bioavailability of tocotrienols: evidence in human studies". Nutrition & Metabolism. 11 (1): 5. doi:10.1186/1743-7075-11-5. PMC 3895660. PMID 24410975.
  7. ^ Sen CK, Khanna S, Roy S (2007). "Tocotrienols in health and disease: the other half of the natural vitamin E family". Molecular Aspects of Medicine. 28 (5–6): 692–728. doi:10.1016/j.mam.2007.03.001. PMC 2435257. PMID 17507086.