- Antioxidant and Cytoprotective Effects of New Diarylheptanoids from Rhynchanthus beesianus
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Rhynchanthus beesianus (Zingiberaceae) has been an important food spice and vegetable in southern China. Fifteen phenolic compounds (1-15) including three new diarylheptanoids, rhynchanines A-C (1-3) and one new phenylpropanoid, 4-O-methylstroside B (9), were isolated from R. beesianus rhizomes. The structures of new compounds were elucidated by comprehensive analyses through NMR, HRMS technique, acid hydrolysis, and Mosher's reaction. Among them, compound 5 is the first isolated natural product and its NMR data are reported. Most of the isolated compounds, especially 3-6 and 8, showed significant antioxidant activities on DPPH, ABTS+ radical scavenging, and FRAP assays. Furthermore, the antioxidant phenolic compounds were evaluated for their cytoprotective capacity against H2O2-induced oxidative stress in HepG-2 cells. Compounds 3 and 5 could significantly inhibit reactive oxygen species production, and compounds 3, 5, and 6 could remarkably prevent the cell apoptosis. Then, the R. beesianus rhizome, which contained phenolic compounds, might serve as a functional food for potential application on preventing oxidative stress-connected diseases.
- Zhu, Pei-Feng,Cheng, Gui-Guang,Zhao, Lan-Qin,Khan, Afsar,Yang, Xing-Wei,Zhang, Bu-Yun,Li, Meng-Cheng,Liu, Ya-Ping,Luo, Xiao-Dong
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p. 6229 - 6239
(2021/06/28)
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- Modular synthesis and biological investigation of 5-hydroxymethyl dibenzyl butyrolactones and related lignans
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Dibenzyl butyrolactone lignans are well known for their excellent biological properties, particularly for their notable anti-proliferative activities. Herein we report a novel, efficient, convergent synthesis of dibenzyl butyrolactone lignans utilizing the acyl-Claisen rearrangement to stereoselectively prepare a key intermediate. The reported synthetic route enables the modification of these lignans to give rise to 5-hydroxymethyl derivatives of these lignans. The biological activities of these analogues were assessed, with derivatives showing an excellent cytotoxic profile which resulted in programmed cell death of Jurkat T-leukemia cells with less than 2% of the incubated cells entering a necrotic cell death pathway.
- Davidson, Samuel J.,Pilkington, Lisa I.,Dempsey-Hibbert, Nina C.,El-Mohtadi, Mohamed,Tang, Shiying,Wainwright, Thomas,Whitehead, Kathryn A.,Barker, David
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- The synthesis and analysis of lignin-bound Hibbert ketone structures in technical lignins
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Understanding the structure of technical lignins resulting from acid-catalysed treatment of lignocellulosic biomass is important for their future applications. Here we report an investigation into the fate of lignin under acidic aqueous organosolv conditions. In particular we examine in detail the formation and reactivity of non-native Hibbert ketone structures found in isolated organosolv lignins from both Douglas fir and beech woods. Through the use of model compounds combined with HSQC, HMBC and HSQC-TOCSY NMR experiments we demonstrate that, depending on the lignin source, both S and G lignin-bound Hibbert ketone units can be present. We also show that these units can serve as a source of novel mono-aromatic compounds following an additional lignin depolymerisation reaction.
- Miles-Barrett, Daniel M.,Neal, Andrew R.,Hand, Calum,Montgomery, James R.D.,Panovic, Isabella,Ojo, O. Stephen,Lancefield, Christopher S.,Cordes, David B.,Slawin, Alexandra M.Z.,Lebl, Tomas,Westwood, Nicholas J.
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p. 10023 - 10030
(2016/11/06)
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- Total synthesis of (-)-Haouamine B pentaacetate and structural revision of haouamine B
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The enantiocontrolled total synthesis of (-)-haouamine B pentaacetate was accomplished via an optically active indane-fused β-lactam, which was prepared by a newly developed Friedel-Crafts reaction. Subsequent cleavage of the β-lactam and an intramolecular McMurry coupling reaction provided the core indane-fused tetrahydropyridine, which led to the elucidation of the structure, as proposed by Trauner and Zuba.
- Momoi, Yuichi,Okuyama, Kei-Ichiro,Toya, Hiroki,Sugimoto, Kenji,Okano, Kentaro,Tokuyama, Hidetoshi
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supporting information
p. 13215 - 13219
(2015/01/09)
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- Prilezhaev dihydroxylation of olefins in a continuous flow process
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Epoxidation of both terminal and non-terminal olefins with peroxy acids is a well-established and powerful tool in a wide variety of chemical processes. In an additional step, the epoxide can be readily converted into the corresponding trans-diol. Batch-wise scale-up, however, is often troublesome because of the thermal instability and explosive character of the peroxy acids involved. This article describes the design and semi-automated optimization of a continuous flow process and subsequent scale-up to preparative production volumes in an intrinsically safe manner. Olefins go with the flow: Prilezhaev dihydroxylation can be performed on a large scale in continuous flow microreactor systems in the oxidation of terminal and internal olefins. Major drivers for a continuous flow process include better control, improved safety, and a faster overall process, leading to a significantly higher throughput. Copyright
- Van Den Broek, Bas A. M. W.,Becker, René,K?ssl, Florian,Delville, Mari?lle M. E.,Nieuwland, Pieter J.,Koch, Kaspar,Rutjes, Floris P. J. T.
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experimental part
p. 289 - 292
(2012/06/01)
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- Metabolism of methylisoeugenol in liver microsomes of human, rat, and bovine origin
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Methylisoeugenol (1,2-dimethoxy-4-propenylbenzene, 1) is a minor constituent of essential oils, naturally occurring as a mixture of cis/trans isomers. 1 is a U.S. Food and Drug Administration-approved food additive and has been given "Generally Recognized as Safe" status. Previously, metabolism of 1 has been studied in the rat, revealing mainly nontoxic cinnamoyl derivatives as major metabolites. However, data concerning the possible formation of reactive intermediary metabolites are not available to date. In this study, the oxidative metabolism of 1 was studied using liver microsomes of rat [not induced, rat liver microsomes (RLM); Aroclor1254 induced RLM (ARLM)], bovine, and human (pooled from 150 donors) origin. Incubations of these microsomes with 1 provided phase I metabolites that were separated by high-performance liquid chromatography (HPLC) and identified by NMR and UV-visible spectroscopy and/or liquid chromatography-mass spectrometry. Identity was confirmed by comparison with 1H NMR spectra of synthesized reference compounds. Formation of metabolites was quantified by HPLC/UV using dihydromethyleugenol (10) synthesized as the internal standard. From incubations of ARLM with 1, seven metabolites could be detected, with 3′- hydroxymethylisoeugenol (2), isoeugenol and isochavibetol (3 + 4), and 6-hydroxymethylisoeugenol (5) being the main metabolites. Secondary metabolites derived from 1 were identified as the α,β-unsaturated aldehyde 3′-oxomethylisoeugenol (6) and 1′,2′-dihydroxy- dihydromethylisoeugenol (7). We were surprised to find that formation of allylic 6-hydroxymethyleugenol (8) was observed starting at approximately 30 min after the beginning of incubations with ARLM. HLM did not form ring-hydroxylated metabolites but were most active in the formation of 6 and 7. ARLM incubations displayed the highest turnover rate and broadest metabolic pattern, presumably resulting from an increased expression of cytochrome P450 enzymes. In conclusion, we present a virtually complete pattern of nonconjugated microsomal metabolites of 1 comprising reactive metabolites and suggest the formation of reactive intermediates that need more investigation with respect to their possible adverse properties. Copyright
- Cartus, Alexander T.,Merz, Karl-Heinz,Schrenk, Dieter
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experimental part
p. 1727 - 1733
(2012/03/22)
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- Organocatalytic approach to (s)-1-arylpropan-2-ols: Enantioselective synthesis of the key intermediate of antiepileptic agent (-)-talampanel
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An efficient organocatalytic route for the preparation of enantioselective synthesis of (S)-1-arylpropan-2-ols derivatives, including the key intermediate of antiepileptic agent (-)-talampanel is described. The key steps involved are L-proline-catalyzed a
- Sawant, Rajiv T.,Waghmode, Suresh B.
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experimental part
p. 2269 - 2277
(2010/09/11)
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- Antioxidative phenylpropanoids from berries of Pimenta dioica
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A phenylpropanoid, threo-3-chloro-1-(4-hydroxy-3-methoxyphenyl)propane- 1,2-diol, was isolated from the berries of Pimenta dioica together with five known compounds, eugenol, 4-hydroxy-3-methoxycinnamaldehyde, 3,4- dimethoxycinnamaldehyde, vanillin and 3-(4-hydroxy-3-methoxyphenyl)propane- 1,2-diol. In addition, the stereochemistry of 3-(4-hydroxy-3- methoxyphenyl)propane-1,2-diol was determined. The phenylpropanoids inhibited autoxidation of linoleic acid in a water-alcohol system.
- Kikuzaki, Hiroe,Hara, Sanae,Kawai, Yayoi,Nakatani, Nobuji
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p. 1307 - 1312
(2007/10/03)
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- Chemocontrolled reduction of aromatic α-ketoesters by NaBH4: Selective synthesis of α-hydroxy esters or 1,2-diols
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α-Hydroxyesters 5a-g or diols 6a-g have been obtained in high yields by reduction of aromatic α-ketoesters 4 once or twice respectively by using NaBH4 as the reducer under suitable conditions. The use of a solvent that does not interact with the reagent allowed the double reduction to occur with only a slight excess of borohydride in very mild conditions.
- Dalla, Vincent,Cotelle, Philippe,Catteau, Jean Pierre
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p. 1577 - 1580
(2007/10/03)
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- Reactions of Lignin-related Cinnamaldehydes and Cinnamyl Alcohols with Borane and Sodium Tetrahydridoborate
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Hydroboration/oxidation of 3-(3,4-dimethoxyphenyl)-2-propen-1-ol gives a mixture of 1-(3,4-dimethoxyphenyl)-1,3-propanediol, 3-(3,4-dimethoxyphenyl)-1,2-propanediol and 3-(3,4-dimethoxyphenyl)-1-propanol; the same compounds are obtained as by-products when the lignin model 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol is synthesized by hydroboration/oxidation of α-(2-methoxyphenoxy)-3,4-dimethoxycinnamic acid. (Z)-3-(3,4-dimethoxyphenyl)-2-propen-1-ol and (E0-α-(2-methoxy-phenoxy)-3,4-dimethoxycinnamic acid give compratively large amounts of 3-(3,4-dimethoxyphenyl)-1,3-propanediol.The results support the view that the by-products are formed via 3-(3,4-dimethoxyphenyl)-2-propen-1-ol.Small amounts of the same by-products are obtained on tetrahydridoborate reduction of (E)-3-(3,4-dimethoxyphenyl)propenal .Analogous results were obtained with (E)-3-phenylpropenal.Models representative of lignin units of the cinnamaldehyde and cinnamyl alcohol types have been prepared and precise 1H NMR spectral data (400 MHz, 300 K) for the compounds are reported.
- Li, Shiming,Lundquist, Knut
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- LITHIATION OF THE BENZENE RING IN THE PRESENCE OF ortho-ALKYL SUBSTITUENTS BEARING ONE OR TWO HETEROATOMS ON THE β-CARBON. A CONVENIENT SYNTHESIS OF MELLEIN AND KIGELIN
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The title reaction can be successfully accomplished by proton-metal exchange with n-butyllithium, and the usually observed elimination to a styrene derivative suppressed, provided an appropriate combination of heteroatoms bound to the β-carbon of the alky
- Napolitano, Elio,Morsani, Massimo,Fiaschi, Rita
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p. 249 - 255
(2007/10/02)
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