Studies on Tocopherol Derivatives. III. Oxidation of δ-Tocopherol and 6-Hydroxy-2, 2, 8-trimethylchroman

Nakamura, Tetsuya; Kijima, Shizumasa

doi:10.1248/cpb.20.1297

Cited by 10 publications

(11 citation statements)

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“…The organic layer was washed with water, with saturated aqueous NaHCO 3 solution, again with water, dried over MgSO 4 , and evaporated in vacuo. The remaining pale brown, oily residue was purified as described in procedure A (88%): mp 81−82 °C; TLC R f = 0.34 ( n -hexane/diethyl ether, v/v = 6:4); 1 H NMR δ 1.21 (s, 6H, H-2a), 1.66 (t, 2H, 3 J = 6.8 Hz, H-3), 2.03 (s, 3H, H-8b), 2.60 (t, 2H, 3 J = 6.8 Hz, H-4), 4.66 (br, 1H, OH), 6.30 (d, 1H, 4 J = 2.9 Hz, H-7), 6.38 (d, 1H, 4 J = 2.9 Hz, H-5); 13 C NMR δ 16.02 (C-8b), 22.80 (C-4), 26.89 (C-2a), 32.84 (C-3), 73.54 (C-2), 112.64 (C-5), 115.68 (C-7), 121.07 (C- 4a), 127.29 (C-8), 146.09 (C-8a), 147.66 (C-6); HRMS (ESI Q-TOF) m / z calcd for C 12 H 16 O 2 [MH] + 193.1223, found [MH] + 193.1284.…”

Section: Methodsmentioning

confidence: 99%

Vitamin E Chemistry. Nitration of Non-α-tocopherols: Products and Mechanistic Considerations

et al. 2007

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In contrast to the alpha-form permethylated at the aromatic ring, non-alpha-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-alpha-tocopherols under nitration conditions was studied. The nitration products of beta-, gamma-, and delta-tocopherol were identified, comprehensively analytically characterized, and their structure was supported by X-ray crystal structure analysis on truncated model compounds. Even under more drastic nitration conditions, no erosion of the stereochemistry at 2-C occurred. The nitrosation of gamma-tocopherol and delta-tocopherol was re-examined, showing the slow oxidation of the initial nitroso products to the corresponding nitro derivatives by air to be superimposed by a fast equilibrium with the tautomeric ortho-quinone monoxime, which only in the case of gamma-tocopherol released hydroxyl amine at elevated temperatures to afford the stable ortho-quinone. Mononitration of delta-tocopherol selectively proceeded at position 5. This selectivity can be explained by the theory of strain-induced bond localization (SIBL) to the quinoid nitration intermediates. Bisnitration was only insignificantly disfavored by the first nitro group, so that under normal nitration conditions offering an excess of nitrating species only the bisnitration product was found.

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Section: Methodsmentioning

confidence: 99%

Vitamin E Chemistry. Nitration of Non-α-tocopherols: Products and Mechanistic Considerations

et al. 2007

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“…The mechanism of dimerization reported by Nilsson et al [20,21] was based on the possible formation of phenoxy radical. The phenoxy radicals having free orto or para position generally dimerize through these centers, forming two types of dimers: diphenol dimers and phenol-phenyl ether dimers [16,17]. The formation of the diphenyl dimers predominates in polar media while the dimerization to phenol-phenyl ethers predominant in nonpolar media [5].…”

Section: Introductionmentioning

confidence: 99%

Influence of added menadione (vitamin K3) on dissolution and dimerization of tocopherols and autoxidation of triacylglycerols during storage of plant oils

Kupczyk¹,

Gogolewski²

2001

Nahrung

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The effect of added menadione (vit. K3) to stored rapeseed and soybean oil on the dissolution and dimerization of natural tocopherols and autoxidation of triacylglycerols was studied. Commercial rapeseed and soybean oils with added menadione and pure oil were stored at +20 degrees C in brown and transparent glass bottles. During storage their peroxide value, changes of the content of fatty acids and dissolution of tocopherols were measured. Destruction of individual tocopherols in tested oils with added menadione stored in both dark and transparent glass bottles were greater than in the oil samples without menadione. However, the degradation of individual tocopherols was different in each oil. Addition of menadione to the rapeseed and soybean oils resulted in the accelerated process of autoxidation of these oils. The oxidative state of the oils was lower in the oils stored in transparent bottles than in the oils stored in brown bottles. The prooxidant activity of menadione was additionally activated by light. Menadione added to the vegetable oils influenced the dissolution of natural tocopherols as well as their dimerization. It is conduced that addition of menadione to vegetable oils decreases their nutritive value.

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“…The 1 H-NMR spectrum of compound 5 showed the presence of an isolated olefinic proton [δH 6.17 (1H, s)], six methyl groups [δH 1.17 (3H, s), 0.94 (3H, d, J = 6.4 Hz), 0.86 (3H, t, J = 7.5 Hz), 0.85 (3H, d, J = 6.8 Hz), 0.82 (3H, d, J = 6.8 Hz), and 0.72 (3H, s)], and many methylene and methine groups at the high field oscillated from 0.95 ppm to 2.68 ppm. Its 13 -11)]. These data of compound 5 were as a steroid derivative, confirmed via the characteristic HMBC correlations of methyl groups to constituted carbons.…”

Section: R-(+)-5-(δ-tocopherol-5'-yl)-δ-tocopherolmentioning

confidence: 63%

“…S1). The 1 H and 13 C-NMR data of 1 appeared as related pairs, indicated the presence of a δ-tocopherol derivative with two similar units (units I and II). Unit I (or II) of 1 showed the signal due to aromatic carbon (δC 120.5) instead of those of (δH 6.37, δC 112.6) in δ-tocopherol, a previously isolated compound from the same extract.…”

Section: Resultsmentioning

confidence: 96%

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Study on chemical composition and α‐glucosidase inhibitory activity from the leaves of Muntingia calabura

Le,

Nguyen,

Van Do

et al. 2023

Vietnam Journal of Chemistry

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Abstract“Trứng cá” (Muntingia calabura) is a special species of the genus Muntingia. Phytochemical studies on the leaves of M. calabura showed that seven compounds were isolated, including R‐(+)‐5‐(δ‐tocopherol‐5'‐yl)‐δ‐tocopherol (1), trans‐phytol (2), ergosta‐4,6,8(14),22‐tetraen‐3‐one (3), ergosterol peroxide (4), stigmasta‐4‐ene‐3,6‐dione (5), 6β‐hydroxystigmast‐4‐en‐3‐one (6), and β‐sitosterol (7). The structures of the compounds were elucidated by mass spectrometry, nuclear magnetic resonance spectroscopy (NMR), and compared to the literature. The biological test result for all isolated compounds showed that compounds 1‐3, and 5‐7 have the ability to inhibit moderately α‐glucosidase with IC50 values ranging from 57.9 to 249.5 μM. Compound 3 processed a significant inhibitory activity effect with an IC50 value of 57.9 μM, more potent than the positive control, acarbose (IC50, 214.5 μM). This is the first time compounds 1‐5 have been reported for the Muntingia genus.

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Studies on Tocopherol Derivatives. III. Oxidation of δ-Tocopherol and 6-Hydroxy-2, 2, 8-trimethylchroman

Cited by 10 publications

References 0 publications

Vitamin E Chemistry. Nitration of Non-α-tocopherols: Products and Mechanistic Considerations

Vitamin E Chemistry. Nitration of Non-α-tocopherols: Products and Mechanistic Considerations

Influence of added menadione (vitamin K3) on dissolution and dimerization of tocopherols and autoxidation of triacylglycerols during storage of plant oils

Study on chemical composition and α‐glucosidase inhibitory activity from the leaves of Muntingia calabura

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