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Vitamin E is one of the most important phytonutrients in edible oils. It consists of eight naturally occuring isomers, a family of four tocopherols (alpha, beta, gamma and delta) and four tocotrienols (alpha, beta, gamma and delta) homologues. 

All the eight isomers share some important traits:

  • The head, or chroman ring in technical term
  • The tail, which is called the phytyl tail for tocopherols
  • The active group on the head of the molecule, which is called the hydroxy group
 


  R1 R2 R3
alpha-tocopherol
alpha-tocotrienol		 CH3 CH3 CH3
beta-tocopherol
beta-tocotrienol		 CH3 H CH3
gamma-tocopherol
gamma-tocotrienol		 H CH3 CH3
delta-tocopherol
delta-tocotrienol		 H H CH3


 

The chroman ring has chemical groups which are called methyl groups attached to it. Alpha has all three available sites filled while beta and gamma have two methyl groups but in different positions. Whereas delta has only one.

The tocotrienol tail has three double bonds while the tocopherol tail has none. In the chemical parlance, bonds are the forces that keep atoms together. A single bond means the atoms share two electrons, a double bond means they share four electrons. 

The structural name for alpha tocopherol is 2, 5, 7, 8 - tetramethyl - 2 - (4" 8" 12" - trimethyltridecyl) - 6 - chromanol whereas the structural name for alpha tocotrienol is 2, 5, 7, 8-tetramethyl - 2 - (4" 8" 12" - trimethyltrideca-3" 7" 11" - trienyl) - 6 - chromanol.