Development of Novel Antioxidants: Design, Synthesis, and Reactivity
摘要:
We are attempting to develop novel synthetic antioxidants aimed at retarding the effects of free-radical induced cell damage. In this paper we discuss the design strategy and report the synthesis of seven novel antioxidants, including six catechols and a benzylic phenol. The bond dissociation enthalpy (BDE) for the most active (weakest) OH bond in each molecule was calculated by theoretical methods, as well as the BDE for the semiquinone radical. Reaction rates with the nitrogen-centered free radical DPPH. were measured in ethyl acetate. The log of k(DPPH) for bimolecular reaction correlated well with the primary BDE. The correlation between rate constants and calculated BDEs shows that the BDE is a good predictor of antioxidant activity with DPPH., suggesting that our design criteria are useful and that these compounds should undergo further testing in cell cultures and in animal models.
A regioselective method for the semisynthesis of phenazine derivatives has been disclosed through an efficient IBX mediated ortho-quinone formation from vitamin E derivatives. High chemo- and regio-selectivity was observed during the oxidation step and the corresponding 5,6-ortho-quinones could react with various phenylenediamines. Thus, this methodology proves its interest as a concise semisynthetic
In contrast to the α-form permethylated at the aromatic ring, non-α-tocopherols possess free aromatic ring positions which enable them to act as potent scavengers of electrophiles in vivo and in vitro. In preparation of enzymatic studies involving peroxynitrite and other nitrating systems, the behavior of non-α-tocopherols under nitration conditions was studied. The nitration products of β-, γ-, and
Iron‐Catalyzed Reaction of γ‐Tocopherol with Methyl Linoleate Hydroperoxides in Solutions
作者:Ryo Yamauchi、Tomomi Kinoshita、Satoshi Iwamoto
DOI:10.1002/aocs.12022
日期:2018.3
acts as an antioxidant by trapping lipid‐peroxyl radicals. This study reports reaction products of γ‐tocopherol with lipid‐peroxyl radicals formed by iron‐catalyzed decomposition of methyl linoleatehydroperoxides (MeLOOH) in toluene and methanol solutions. The products in toluene solution were tocored, methyl (8a‐dioxy‐γ‐tocopherone)‐epoxyoctadecenoates (γT‐OO‐epoxyMeL), methyl (8a‐dioxy‐γ‐tocophe
作者:Niel C. Hoglen、Stephen C. Waller、I. Glenn Sipes、Daniel C. Liebler
DOI:10.1021/tx960200h
日期:1997.4.1
detected in reactions involving peroxynitrite. Oxidation of gamma-TH by peroxynitrite involves nitration and electron transfer reactions. Since the product distribution in oxidations with NO2+BF4- differed substantially from that in oxidations with peroxynitrite and SIN-1, NO2+ appeared not to be the principal species involved in NGT formation. Nitration of gamma-TH may involve either peroxynitrite or some
过氧亚硝酸盐与γ-生育酚(gamma-TH)在甲醇/磷酸钾缓冲溶液中的反应导致形成四个主要产物,被鉴定为2,7,8-三甲基-2-(4,8,12) -(三甲基癸基)-5-硝基-6-苯并甲醇++(NGT),2,7,8-三甲基-2-(4,8,12-三甲基癸基)-5,6-苯并二氢萘醌(有环)和两个8a非对映异构体-(羟基)-γ-生育酚。NGT是在这些反应中形成的主要产物,并通过增加Fe(3 +)-EDTA的量适度增加了它的形成。当γ-TH暴露于3-吗啉代亚砜亚胺(SIN-1)时,也形成了Tocored和NGT,该化合物会分解形成过氧亚硝酸盐。当γ-TH与硝化剂NO2 + BF4-在乙腈或甲醇/磷酸钾缓冲液中反应时,还会生成NGT和tocored,但检测到的主要产物是γ-生育酚醌(γ-TQ)。在涉及过氧亚硝酸盐的反应中未检测到该产物。过亚硝酸盐氧化γ-TH涉及硝化和电子转移反应。由于用NO2 + B
Novel tocopheryl compounds XXIV. Studies into the nitrosation chemistry of γ-tocopherol: preparation of 5-nitroso-γ-tocopherol via an organomercury derivative of vitamin E
exists in equilibrium with its ortho-quinone monoxime tautomer 6, the latter being the major component with >99%. NMR and analytical data of the tautomeric couple are reported for the first time. The chemistry of the nitrosation of γ-tocopherol was studied in detail. In the presence of oxygen, 5 is readily oxidized to 5-nitro-γ-tocopherol (7), whereas at elevated temperatures an additional process, the