- Efficient oxidation of β?carotene in μ-carbido diiron octapropyltetraazaporphyrin–tBuOOH system
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The oxidative decomposition of β?carotene mediated by μ-carbido diiron octapropyltetraazaporphyrin ([FeOPrTAP]2C)–tBuOOH system was investigated in benzene. Interaction between tBuOOH and the binuclear complex resulted in the generation of powerful high-oxidized species those are capable of oxidizing the employed substrate within the limits of several minutes. The explanation for such reactivity behavior involves the existence of a mixture of reactive intermediates in the reaction medium: more stable singly oxidized at the macrocyclic ligand π-cation radical as well as much more reactive dication species that is more contributing to the reaction rate. The introduction of imidazole into the coordination sphere of the initial diiron complex accelerates the β?carotene destruction because of generation of a powerful high-oxidizing species, which is capable of oxidizing β?carotene as well as the applied organic peroxide resulting in dioxygen release. Catalytic behavior of all the observed active intermediates was supported by recycling of the reaction under carotene adding. The quantitative characteristics of reactivity of studied systems were obtained and the possible reaction mechanisms were proposed.
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- Relative one-electron reduction potentials of carotenoid radical cations and the interactions of carotenoids with the vitamin E radical cation
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Pulse radiolysis studies have been used to determine the electron- transfer rate constants between various pairs of carotenoids, one of which is present as the radical cation. These dietary carotenoids include those of importance to vision, namely zeaxanthin and lutein. These results have suggested the order of relative ease of electron transfer between six carotenoids. Additional experiments, involving electron transfer between astaxanthin (ASTA), β-apo-8'-carotenal (APO), and vitamin E (TOH), lead to the following order in terms of relative ease of electron transfer for the seven carotenoid radical cations studied: astaxanthin > β-apo-8'-carotenal > canthaxanthin > lutein > zeaxanthin > β-carotene > lycopene, such that lycopene is the strongest reducing agent (the most easily oxidized) and astaxanthin is the weakest, and the radical cations of the visual carotenoids, lutein (LUT) and zeaxanthin (ZEA), are reduced by lycopene (LYC) but not by β-carotene (β-CAR). Work on 7,7'-dihydro-β-carotene (77DH) and vitamin E allows us to better understand the interaction of the vitamin E radicals with carotenoids.
- Edge, Ruth,Land, Edward J.,McGarvey, David,Mulroy, Louise,Truscott, T. George
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- Kinetics of β-Carotene Oxidation in the Presence of Highly Active Forms of μ-Carbido Diiron(IV) Tetraphenylporphyrinate
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Abstract: The oxidative destruction of β-carotene in the presence of highly oxidized forms of μ-carbido-bis[(5,10,15,20-tetraphenyl-21H,23H-porphyrinato)iron(IV)] (1 → 3) or its analog with axially coordinated imidazole (2 → 4) obtained under the action of tert-butyl hydroperoxide tBuOOH was studied by spectrophotometry. It was found that compound 3 is the oxo form of compound 1 singly oxidized at the macrocyclic ligand (π radical cation) under the action of which β-carotene is oxidized with a rate constant k = 3.3 L2 mol–2 s–1. A?conclusion is drawn that short-lived compound 4 has unique EAS and is capable of oxidizing tBuOOH to form O2, which makes it possible to consider it the model of peroxidase. The value of k for the reaction with the participation of β-carotene and compound 4 (k = 10.3 L2 mol–2 s–1) is three times higher than that with the participation of compound 3. If a new portion of β-carotene is added, the process of its oxidative destruction in the presence of compounds 3 or 4 occurs without additives of the dimeric complex and peroxide. A?possible nature of compound 4 is discussed, as well as the influence of N-base in the coordination sphere of the complex on the nature of active intermediates and the rate of β-carotene decomposition.
- Simonova,Zaitseva,Tyulyaeva, E. Yu.,Zdanovich,Koifman
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- Mild oxidative cleavage of β,β-carotene by dioxygen induced by a ruthenium porphyrin catalyst: Characterization of products and of some possible intermediates
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Mild oxidative cleavage of β,β-carotene by dioxygen is induced by a ruthenium tetramesitylporphyrin catalyst, and it leads to the full possible range of β-apocarotenals and β-apocarotenones. The slow reaction kinetics allow the sequence of events leading to double bond cleavage over a period of 24 h to be monitored by HPLC-DAD and HPLC-MS.
- Caris-Veyrat,Amiot,Ramasseul,Marchon
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- Preparation method of beta-apo-8 '-carotene aldehyde
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The invention discloses a preparation method of beta-apo-8 '-carotene aldehyde, which comprises the following steps: by using beta-apo-8-carotene ethyl ester as a raw material, conducting reducing tofor an alcohol under the action of a reducing agent, and conducting oxidizing to form beta-apo-8'-carotene aldehyde, wherein the reducing agent is one or more of sodium borohydride, lithium borohydride and lithium aluminum hydride, and an oxidizing agent is one or more of pyridinium chlorochromate, hydrogen peroxide, manganese dioxide and 4-hydroxy-2,2,6,6-tetramethyl-piperidinooxy. The target product beta-apo-8 '-carotene aldehyde can be generated only through two-step reaction, the reaction raw materials are cheap and easy to obtain, the process route is simple, the reaction conditions are mild, the process operation is easy to implement, and the method has great industrial value.
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Paragraph 0035; 0039-0042; 0043; 0045-0046; 0049; 0053-0054
(2021/02/24)
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- Method for preparing beta-Apo-8'-carotenal
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The invention discloses a method for preparing beta-Apo-8'-carotenal. The method includes steps of (1) synthesizing raw materials 2, 6, 6-trimethyl-1- cyclohexanemethanol and triphenylphosphine as raw materials into 2, 6, 6-trimethyl-1-cyclohexene methyl triphenylphosphine salt; (2) subjecting 2, 6, 6-trimethyl-1-cyclohexene methyl triphenylphosphine salt and 2, 6, 11, 15-tetramethyl-2, 4, 6, 8, 10, 12, 14-hexadecanoyl heptaene dialdehyde to wittig reaction to obtain beta-Apo-8'-carotenal. The method using 2, 6, 6-trimethyl-1- cyclohexanemethanol as raw materials is safe in reaction and is a novel method.
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Paragraph 0030; 0031; 0035
(2016/11/21)
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- Selected cis/trans isomers of carotenoids formed by bulk electrolysis and iron(III) chloride oxidation
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Bulk electrolysis and chemical oxidation with FeCl3 of all-trans canthaxanthin (I) and 8′-apo-β-caroten-8′-al (II) gave primarily the 9- and 13-cis-isomers, which were separated by HPLC and identified by 1H NMR spectroscopy. Optical absorption measurements showed that the 15-cis, 9,13-di-cis isomers of I are also formed by these methods. In the case of the unsymmetrical compound II, additional isomers were formed. The cis isomers account for about 40-60% of products formed. Formation of the isomers is believed to occur by rotation about certain bonds in the cation radicals or dications, which are formed in the oxidation processes. The neutral cis species are then formed by an electron exchange reaction of the cis-cation radicals with neutral all-trans carotenoids in solution. The electrochemical and iron(III) chloride oxidation induced isomerization are shown to be efficient and improved methods for forming selected carotenoid isomers.
- Wei, Chih-Chang,Gao, Guoqiang,Kispert, Lowell D.
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p. 783 - 786
(2007/10/03)
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