Tokoferol

Tokoferoli (TCP) su klasa hemijskih jedinjenja koja se sastoji od metilisanih fenola. Mnoga od ovih organskih jedinjenja imaju aktivnost vitamina E. Njihova vitaminska aktivnost je prvo uočena 1936. na dijetetskim faktorima plodnosti kod pacova, te su nazvani "tokoferolima" od grčkih reči “τόκος” [ređenje], i “φέρειν”, [nositi]. Sufiks "-ol" označava njihov status alkohola.

Alfa-tokoferol je glavni izvor. On je nađen u suplementima i ishrani. Glavni evropski prehrambeni izvor su maslinovo i suncokretovo ulje,^[1] dok je gama-tokoferol najzastupljenija forma u američkoj ishrani usled visokog unosa sojinog i kukuruznog ulja.^[1]^[2] Kad se dodaje prehrambenim proizvodima, alfa-tokoferol se označava E brojem E307 u Evropskoj Uniji.

Tokotrienoli, koji su srodna jedinjenja, takođe imaju aktivnost vitamina E. Svi ovi derivati sa vitaminskom aktivnošću se mogu korektno nazvati vitamin E. Tokoferoli i tokotrienoli su u masnoći rastvorni antioksidansi, a imaju i niz drugih funkcija u telu.

Oblici

Vitamin E se javlja u osam različitih formi, četiri tokoferola i četiri tokotrienola. Svi sadrže prsten hromanola, sa hidroksilnom grupom koja može da donira atom vodonika da redukuje slobodne radikale i hidrofobnim bočnim lancom koji omogućava penetraciju u biološke membrane.

Tokoferoli i tokotrienoli se javljaju u alfa, beta, gama i delta formama, koje su određene brojem i pozicijom metil grupa na prstenu hromanola.

Forma	R1	R2	R3	Struktura
alfa-Tokoferol	Me	Me	Me
beta-Tokoferol	Me	H	Me
gama-Tokoferol	H	Me	Me
delta-Tokoferol	H	H	Me

Reference

↑ ^1,0 ^1,1 Karl-Heinz Wagner, Afaf Kamal-Eldin, Ibrahim Elmadfa (2004). „Gamma-tocopherol--an underestimated vitamin?”. Annals of nutrition and metabolism 48 (3): 169-88. DOI:10.1159/000079555. PMID 15256801. »In North America, the intake of γ-tocopherol has been estimated to exceed that of α-tocopherol by a factor of 2–4 ... due to the fact that soybean oil is the predominant vegetable oil in the American diet (76.4%) followed by corn oil and canola oil (both 7%) ... The supply of dietary fats ... is much more diverse in Europe ... The oils mainly consumed in Europe, i.e. sunflower, olive and canola oil, provide less γ-tocopherol but more α-tocopherol ... [T]he ratio of α-:γ-tocopherol is at least 1:2. Therefore, the average γ-tocopherol intake can be estimated as 4–6 mg/day, which is about 25–35% of the USA intake. In accordance with the lower estimated European intake of γ-tocopherol, the serum levels of γ-tocopherol in European populations are 4–20 times lower than that of α-tocopherol«
↑ Jiang, Q; Christen, S; Shigenaga, MK; Ames, BN (2001). „gamma-tocopherol, the major form of vitamin E in the US diet, deserves more attention”. The American journal of clinical nutrition 74 (6): 714–22. PMID 11722951.

Spoljašnje veze

Prehrambeni suplementi vitamina E
Procena rizika Arhivirano 2006-01-02 na Wayback Machine-u

[Wagner_et_al,_2004-1] 1,0 ^1,1 Karl-Heinz Wagner, Afaf Kamal-Eldin, Ibrahim Elmadfa (2004). „Gamma-tocopherol--an underestimated vitamin?”. Annals of nutrition and metabolism 48 (3): 169-88. DOI:10.1159/000079555. PMID 15256801. »In North America, the intake of γ-tocopherol has been estimated to exceed that of α-tocopherol by a factor of 2–4 ... due to the fact that soybean oil is the predominant vegetable oil in the American diet (76.4%) followed by corn oil and canola oil (both 7%) ... The supply of dietary fats ... is much more diverse in Europe ... The oils mainly consumed in Europe, i.e. sunflower, olive and canola oil, provide less γ-tocopherol but more α-tocopherol ... [T]he ratio of α-:γ-tocopherol is at least 1:2. Therefore, the average γ-tocopherol intake can be estimated as 4–6 mg/day, which is about 25–35% of the USA intake. In accordance with the lower estimated European intake of γ-tocopherol, the serum levels of γ-tocopherol in European populations are 4–20 times lower than that of α-tocopherol«

[gamma-2] Jiang, Q; Christen, S; Shigenaga, MK; Ames, BN (2001). „gamma-tocopherol, the major form of vitamin E in the US diet, deserves more attention”. The American journal of clinical nutrition 74 (6): 714–22. PMID 11722951.

[1]

[2]