Vitamin E models. Can the anti-oxidant and pro-oxidant dichotomy of α-tocopherol be related to ionic ring closing and radical ring opening redox reactions?
The free radical scavenging mechanism, leading to a quinodal structure via an oxidative ring opening is exothermic. However, the ionic oxidative ring opening is endothermic. Consequently, the ionic reductive ring closing must be exothermic. This leads to the suggestion that Vitamin E may be recovere...
Elmentve itt :
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| Dokumentumtípus: | Cikk |
| Megjelent: |
2003
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| Sorozat: | JOURNAL OF MOLECULAR STRUCTURE: THEOCHEM
620 No. 2-3 |
| Tárgyszavak: | |
| doi: | 10.1016/S0166-1280(02)00604-8 |
| mtmt: | 1132565 |
| Online Access: | http://publicatio.bibl.u-szeged.hu/28639 |
| Tartalmi kivonat: | The free radical scavenging mechanism, leading to a quinodal structure via an oxidative ring opening is exothermic. However, the ionic oxidative ring opening is endothermic. Consequently, the ionic reductive ring closing must be exothermic. This leads to the suggestion that Vitamin E may be recovered, unchanged, thus effectively acts as a catalyst for the following reaction 2HOO + H3O(+) + NADH --> 2HOOH + H2O + NAD((+)), DeltaE approximate to 120 kcal mol(-1). As Vitamin E is biologically recycled, a single alpha-tocopherol molecule may convert numerous HOO radical to H2O2 which is accumulated if not removed at the same rate, enzymatically, with the participation of catalase (Fe) or glutathione peroxidase, GP,(Se). This accumulation of peroxide, which may be referred to as a 'peroxide traffic jam', may well be the reason of the prooxidant effect of Vitamin E. (C) 2002 Published by Elsevier Science B.V. |
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| Terjedelem/Fizikai jellemzők: | 93-106 |
| ISSN: | 0166-1280 |