3D model (JSmol)
|E number||E307a (antioxidants, ...)|
CompTox Dashboard (EPA)
|Molar mass||430.71 g/mol|
|Appearance||yellow-brown viscous liquid|
|Melting point||2.5 to 3.5 °C (36.5 to 38.3 °F; 275.6 to 276.6 K)|
|Boiling point||200 to 220 °C (392 to 428 °F; 473 to 493 K) at 0.1 mmHg|
|NFPA 704 (fire diamond)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
?-Tocopherol is a type of vitamin E. It has E number "E307". Vitamin E exists in eight different forms, four tocopherols and four tocotrienols. All feature a chromane ring, with a hydroxyl group that can donate a hydrogen atom to reduce free radicals and a hydrophobic side chain which allows for penetration into biological membranes. Compared to the others, ?-tocopherol is preferentially absorbed and accumulated in humans.
Vitamin E is found in a variety of tissues, being lipid-soluble, and taken up by the body in a wide variety of ways. The most prevalent form, ?-tocopherol, is involved in molecular, cellular, biochemical processes closely related to overall lipoprotein and lipid homeostasis. Ongoing research is believed to be "critical for manipulation of vitamin E homeostasis in a variety of oxidative stress-related disease conditions in humans." One of these disease conditions is the ?-tocopherol role in the use by malaria parasites to protect themselves from the highly oxidative environment in erythrocytes.
?-Tocopherol has three stereocenters, so it is a chiral molecule. The eight stereoisomers of ?-tocopherol differ the configuration on these stereocenters. RRR-?-tocopherol is the natural one. Older name of RRR-?-tocopherol is d-?-tocopherol, but this d/l naming should be no longer used, because whether l-?-tocopherol should mean SSS enantiomer or the SRR diastereomer is not clear, from historical reasons. The SRR may be named 2-epi-?-tocopherol, the diastereomeric mixture of RRR-?-tocopherol and 2-epi-?-tocopherol may be called 2-ambo-?-tocopherol (formerly named dl-?-tocopherol). The mixture of all eight diastereomers is called all-rac-?-tocopherol
One IU of tocopherol is defined as 2/3 milligrams of RRR-?-tocopherol (formerly named d-?-tocopherol, or sometimes ddd-?-tocopherol). 1 IU is also defined as 1 mg of an equal mix of the eight stereoisomers, which is a racemic mixture, all-rac-?-tocopheryl acetate. This mix of stereoisomers is often called dl-?-tocopheryl acetate. However, 1 IU of this mixture of diastereomers is not now considered equivalent to 1 IU of natural RRR-?-tocopherol, and the Institute of Medicine and the USDA now convert IUs of the racemic mixture to milligrams of equivalent RRR using 1 IU racemic mixture = 0.45mg "?-tocopherol".