Inhibition of oxidative metabolism of tocopherols with ω-N-heterocyclic derivatives of vitamin E
作者:Stephan Ohnmacht、Phillip Nava、Ryan West、Robert Parker、Jeffrey Atkinson
DOI:10.1016/j.bmc.2008.07.020
日期:2008.8
The oxidative metabolism of tocopherols and tocotrienols by monooxygenases is a key factor in the plasma and tissue clearance of forms of vitamin E other than alpha-tocopherol. It is well known that a commonly ingested form of vitamin E, gamma-tocopherol, has greatly reduced plasma half-life (faster clearance) than alpha-tocopherol. The tocotrienols are metabolized even faster than gamma-tocopherol. Both gamma-tocopherol and alpha- and delta-tocotrienol possess intriguing biological activities that are different from alpha-tocopherol, making them potentially of interest for therapeutic use. Unfortunately, the fast clearance of non-alpha-tocopherols from animal tissues is a significant hurdle to maximizing their effect(s) as dietary supplements. We report here the design and synthesis of N-heterocycle-containing analogues of alpha-tocopherol that act as inhibitors of Cyp4F2, the key monooxygenase responsible for omega-hydroxylation of the side chain of tocols. In particular, an omega-imidazole containing compound, 1, [(R)-2-(9-(1H-imidazol-1-yl)nonyl)-2,5,7,8-tetramethylchroman-6-ol] had an ED50 for inhibition of gamma-CEHC production from c-tocopherol of similar to 1 nM when tested in HepG2 cells in culture. Furthermore, feeding of 1 to mice along with rapidly metabolized delta-tocopherol, resulted in a doubling of the delta-tocopherol/alpha-tocopherol ratio in liver ( P<0.05). Thus, 1 may be a useful adjuvant to the therapeutic use of non-alpha-tocopherols. (C) 2008 Elsevier Ltd. All rights reserved.