Alpha-Tocopherol
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Alpha-Tocopherol
?-Tocopherol[1]
Tocopherol, alpha-.svg
Sample of alpha-tocopherol.jpg
Names
IUPAC name
(2R)-2,5,7,8-Tetramethyl-2-[(4R,8R)-(4,8,12-trimethyltridecyl)]chroman-6-ol
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.375
EC Number
  • 200-412-2
E number E307a (antioxidants, ...)
UNII
Properties
C29H50O2
Molar mass 430.71 g/mol
Appearance yellow-brown viscous liquid
Density 0.950 g/cm3
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
Pharmacology
A11HA03 (WHO)
Hazards
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
1
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
?Y verify (what is ?Y?N ?)
Infobox references

?-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."[2] 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.[3]

Stereoisomers

?-Tocopherol has three stereocenters, so it is a chiral molecule.[4] The eight stereoisomers of ?-tocopherol differ the configuration on these stereocenters. RRR-?-tocopherol is the natural one.[5] 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[6]

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".[7]


References

  1. ^ Merck Index, 11th Edition, 9931.
  2. ^ Rigotti A (2007). "Absorption, transport, and tissue delivery of vitamin E". Molecular Aspects of Medicine. 28 (5-6): 423-36. doi:10.1016/j.mam.2007.01.002. PMID 17320165.
  3. ^ Shichiri M, Ishida N, Hagihara Y, Yoshida Y, Kume A, Suzuki H (2019). "Probucol induces the generation of lipid peroxidation products in erythrocytes and plasma of male cynomolgus macaques". Journal of Clinical Biochemistry and Nutrition. 64 (2): 129-142. doi:10.3164/jcbn.18-7. PMC 6436040. PMID 30936625.
  4. ^ Jensen SK, Lauridsen C (2007). "Alpha-tocopherol stereoisomers". Vitamins and Hormones. 76: 281-308. doi:10.1016/S0083-6729(07)76010-7. PMID 17628178.
  5. ^ Brigelius-Flohé R, Traber MG (July 1999). "Vitamin E: function and metabolism". FASEB Journal. 13 (10): 1145-55. doi:10.1096/fasebj.13.10.1145. PMID 10385606.
  6. ^ IUPAC Nomenclature of Tocopherols and Related Compounds
  7. ^ "Composition of Foods Raw, Processed, Prepared USDA National Nutrient Database for Standard Reference, Release 20" (PDF). USDA. February 2008. Archived from the original (PDF) on 2012-02-19.

  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.

Alpha-Tocopherol
 



 



 
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