- Dirigent Proteins Guide Asymmetric Heterocoupling for the Synthesis of Complex Natural Product Analogues
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Phenylpropanoids are a class of abundant building blocks found in plants and derived from phenylalanine and tyrosine. Phenylpropanoid polymerization leads to the second most abundant biopolymer lignin while stereo- and site-selective coupling generates an array of lignan natural products with potent biological activity, including the topoisomerase inhibitor and chemotherapeutic etoposide. A key step in etoposide biosynthesis involves a plant dirigent protein that promotes selective dimerization of coniferyl alcohol, a common phenylpropanoid, to form (+)-pinoresinol, a critical C2 symmetric pathway intermediate. Despite the power of this coupling reaction for the elegant and rapid assembly of the etoposide scaffold, dirigent proteins have not been utilized to generate other complex lignan natural products. Here, we demonstrate that dirigent proteins from Podophyllum hexandrum in combination with a laccase guide the heterocoupling of natural and synthetic coniferyl alcohol analogues for the enantioselective synthesis of pinoresinol analogues. This route for complexity generation is remarkably direct and efficient: three new bonds and four stereocenters are produced from two different achiral monomers in a single step. We anticipate our results will enable biocatalytic routes to difficult-to-access non-natural lignan analogues and etoposide derivatives. Furthermore, these dirigent protein and laccase-promoted reactions of coniferyl alcohol analogues represent new regio- and enantioselective oxidative heterocouplings for which no other chemical methods have been reported.
- Kim, Stacie S.,Sattely, Elizabeth S.
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p. 5011 - 5021
(2021/05/04)
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- Incorporation of catechyl monomers into lignins: Lignification from the non-phenolic end: Via Diels-Alder cycloaddition?
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Canonical lignification occurs via the coupling of phenolic radicals, in which chain extension can occur only from phenolic ends of growing polymer chains. Radical coupling of catechyl monomers, including caffeyl and 5-hydroxyconiferyl alcohols, gives ris
- Ando, Daisuke,Boerjan, Wout,Elder, Thomas J.,Eugene, Alexis,Kim, Hoon,Lu, Fachuang,Ralph, John,Tobimatsu, Yuki,Vanholme, Ruben
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p. 8995 - 9013
(2021/11/27)
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- Pinoresinol-lariciresinol reductase: Substrate versatility, enantiospecificity, and kinetic properties
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Two western red cedar pinoresinol-lariciresinol reductase (PLR) homologues were studied to determine their enantioselective, substrate versatility, and kinetic properties. PLRs are downstream of dirigent protein engendered, coniferyl alcohol derived, stereoselective coupling to afford entry into the 8- and 8′-linked furofuran lignan, pinoresinol. Our investigations showed that each PLR homolog can enantiospecifically metabolize different furofuran lignans with modified aromatic ring substituents, but where phenolic groups at both C4/C4′ are essential for catalysis. These results are consistent with quinone methide intermediate formation in the PLR active site. Site-directed mutagenesis and kinetic measurements provided additional insight into factors affecting enantioselectivity and kinetic properties. From these data, PLRs can be envisaged to allow for the biotechnological potential of generation of various lignan skeleta, that could be differentially “decorated” on their aromatic ring substituents, via the action of upstream dirigent proteins.
- Davin, Laurence B.,Hwang, Julianne K.,Lewis, Norman G.,Moinuddin, Syed G. A.
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- Sesquiterpenoids, phenolic and lignan glycosides from the roots and rhizomes of Clematis hexapetala Pall. and their bioactivities
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Approximately 17 compounds were isolated from a 60% EtOH aqueous extract of the roots and rhizomes of Clematis hexapetala Pall., including three new guaianolide sesquiterpenoids with 5/7/5-fused rings and 3S-configuration (1–3), five new prenylated tetra-substituted phenolic glycosides (4–8) with 6/6-fused 9H-benzopyran skeleton (5) and 6/7-fused 7,10-dihydro-benzoxepin skeleton (6–8), one new isoferulyl glucoside (9), two new furofuran lignan diglucosides (10–11), and six known compounds. The chemical structures of the new compounds were elucidated via spectroscopic data and electronic circular dichroism (ECD) analyses in combination with a modified Mosher's method. The possible biosynthetic relationships of prenylated tetra-substituted phenols were postulated. In the in vitro assays, compound 16 exhibited moderate TNF-α secretion inhibitory activity with IC50 value of 3.419 μM. Compounds 14–16 displayed potent PTP1B enzymatic inhibitory activities with inhibition ratios of 48.30–86.00%. And compound 16 showed significant PTP1B enzymatic inhibition with IC50 value of 4.623 μM.
- Cai, Lu,Han, Shao-Wei,Li, Shuai,Shao, Si-Yuan
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- Isolation of enantiomeric furolactones and furofurans from Rubus idaeus L. with neuroprotective activities
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A phytochemical study on the fruits of Rubus idaeus L. (Rosaceae) yielded eight pairs of enantiomeric lignans, including one undescribed furolactone named (?)-idaeusinol A and six undescribed furofuran derivatives named (+/?)-idaeusinol B–D. The structures of these isolated compounds were elucidated by spectroscopic analyses and a combination of computational techniques including gauge-independent atomic orbital (GIAO) calculation of 1D NMR data and TD-DFT calculation of electronic circular dichroism (ECD) spectra. Bioactivity screenings suggested that (+)-idaeusinol D exhibited the most significant protective effect against H2O2-induced neurotoxicity at the concentration of 25 μM. In contrast, (?)-idaeusinol D, as the enantiomer of (+)-idaeusinol D, showed no effect against H2O2-induced neurotoxicity at both 25 and 50 μM concentration.
- Zhou, Le,Han, Feng-Ying,Lu, Li-Wei,Yao, Guo-Dong,Zhang, Ying-Ying,Wang, Xiao-Bo,Lin, Bin,Huang, Xiao-Xiao,Song, Shao-Jiang
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p. 122 - 129
(2019/05/29)
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- An Efficient Method for Determining the Relative Configuration of Furofuran Lignans by 1H NMR Spectroscopy
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An efficient 1H NMR spectroscopic approach for determining the relative configurations of lignans with a 7,9′:7′,9-diepoxy moiety has been established. Using the chemical shift differences of H2-9 and H2-9′ (ΔδH-9 and ΔδH-9′), the configurations of 8-H and 8-OH furofuran lignans can be rapidly and conveniently determined. The rule is applicable for data acquired in DMSO-d6, methanol-d4, or CDCl3. Notably, the rule should be applied carefully when the C-2 or C-6 substituent of the aromatic rings may alter the dominant conformers of the furofuran moiety.
- Shao, Si-Yuan,Yang, Ya-Nan,Feng, Zi-Ming,Jiang, Jian-Shuang,Zhang, Pei-Cheng
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supporting information
p. 1023 - 1028
(2018/05/01)
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- A bio-inspired total synthesis of tetrahydrofuran lignans
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Lignan natural products comprise a broad spectrum of biologically active secondary metabolites. Their structural diversity belies a common biosynthesis, which involves regioand chemoselective oxidative coupling of propenyl phenols. Attempts to replicate this oxidative coupling have revealed significant challenges for controlling selectivity, and these challenges have thus far prevented the development of a unified biomimetic route to compounds of the lignan family. A practical solution is presented that hinges on oxidative ring opening of a diarylcyclobutane to intercept a putative biosynthetic intermediate. The effectiveness of this approach is demonstrated by the first total synthesis of tanegool in 4 steps starting from ferulic acid, as well as a concise synthesis of the prototypical furanolignan pinoresinol.
- Albertson, Anna K. F.,Lumb, Jean-Philip
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supporting information
p. 2204 - 2208
(2015/02/19)
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- The synthesis and analysis of advanced lignin model polymers
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If the lignin-first biorefinery concept becomes a reality, high quality lignins close in structure to native lignins will become available in large quantities. One potential way to utilise this renewable material is through depolymerisation to aromatic chemicals. This will require the development of new chemical methods. Here, we report the synthesis and characterisation of advanced lignin model polymers to be used as tools to develop these methods. The controlled incorporation of the major linkages in lignin is demonstrated to give complex hardwood and softwood lignin model polymers. These polymers have been characterised by 2D HSQC NMR and GPC analysis and have been compared to isolated lignins.
- Lancefield,Westwood
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supporting information
p. 4980 - 4990
(2015/11/16)
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- Non-host disease resistance response in pea (Pisum sativum) pods: Biochemical function of DRR206 and phytoalexin pathway localization
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Continually exposed to potential pathogens, vascular plants have evolved intricate defense mechanisms to recognize encroaching threats and defend themselves. They do so by inducing a set of defense responses that can help defeat and/or limit effects of invading pathogens, of which the non-host disease resistance response is the most common. In this regard, pea (Pisum sativum) pod tissue, when exposed to Fusarium solani f. sp. phaseoli spores, undergoes an inducible transcriptional activation of pathogenesis-related genes, and also produces (+)-pisatin, its major phytoalexin. One of the inducible pathogenesis-related genes is Disease Resistance Response-206 (DRR206), whose role in vivo was unknown. DRR206 is, however, related to the dirigent protein (DP) family. In this study, its biochemical function was investigated in planta, with the metabolite associated with its gene induction being pinoresinol monoglucoside. Interestingly, both pinoresinol monoglucoside and (+)-pisatin were co-localized in pea pod endocarp epidermal cells, as demonstrated using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging. In addition, endocarp epidermal cells are also the site for both chalcone synthase and DRR206 gene expression. Taken together, these data indicate that both (+)-pisatin and pinoresinol monoglucoside function in the overall phytoalexin responses.
- Seneviratne, Herana Kamal,Dalisay, Doralyn S.,Kim, Kye-Won,Moinuddin, Syed G.A.,Yang, Hong,Hartshorn, Christopher M.,Davin, Laurence B.,Lewis, Norman G.
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p. 140 - 148
(2015/05/27)
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- Two-Step One-Pot Synthesis of Pinoresinol from Eugenol in an Enzymatic Cascade
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The phytoestrogen pinoresinol is a high-value compound that has a protective effect against diverse health disorders, and thus is of interest for the pharmaceutical industry. Isolation of pinoresinol from plants suffers from low yields, and its chemical synthesis involves several work-up steps. In this study we devised a novel two-step one-pot enzymatic cascade combining a vanillyl-alcohol oxidase and a laccase for the production of pinoresinol from eugenol via the intermediate coniferyl alcohol. Along with the well-characterized vanillyl-alcohol oxidase from Penicillium simplicissimum used to catalyze the oxidation of eugenol, enzyme screening revealed three bacterial laccases that were appropriate for the synthesis of pinoresinol from coniferyl alcohol. The cascade was optimized regarding enzyme ratios, pH value, and the presence of organic solvents. Under optimized conditions, pinoresinol concentration achieved 4.4 mM (1.6 gl-1), and this compound was isolated and analyzed. Increasing value: The high-value compound pinoresinol is synthesized in a two-step one-pot process combining the vanillyl-alcohol oxidase from Penicillium simplicissimum (PsVAO) and a bacterial laccase starting from the inexpensive substrate eugenol. tBME=tert-butyl methyl ether.
- Ricklefs, Esther,Girhard, Marco,Koschorreck, Katja,Smit, Martha S.,Urlacher, Vlada B.
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p. 1857 - 1864
(2015/06/23)
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- On the reactivity of the Melanocarpus albomyces laccase and formation of coniferyl alcohol dehydropolymer (DHP) in the presence of ionic liquid 1-allyl-3-methylimidazolium chloride
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Some ionic liquids are able to dissolve wood, including lignin and lignocellulose, and thus they provide an efficient reaction media for modification of globally abundant wood-based polymers. Lignin can be modified with laccases (EC 1.10.3.2), multicopper
- Lahtinen, Maarit,Viikari, Liisa,Karhunen, Pirkko,Asikkala, Janne,Kruus, Kristiina,Kilpel?inen, Ilkka
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p. 169 - 177
(2013/01/15)
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- New lignans from the aerial parts of Rudbeckia laciniata
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Three new furofuran lignans, (+)-4,4′-O-diangeloylpinoresinol (1), (+)-4,4′-O-diangeloylmedioresinol (2), and (+)-4,4′-O- diangeloylsyringaresinol (3), together with the known compound (+)-syringaresinol, were isolated from the MeOH extract of Rudbeckia l
- Lee, Seung Young,Woo, Kyeong Wan,Kim, Chung Sub,Lee, Dong Ung,Lee, Kang Ro
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p. 320 - 325
(2013/03/28)
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- Four new cytotoxic tetrahydrofuranoid lignans from sinopodophyllum emodi
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Four new tetrahydrofuranoid lignans, (-)-tanegool-7′-methyl ether (1), (+)-7′-methoxylariciresinol (2), sinolignan C (3), and epipinoresinol-4,4-di-Oβ- D-glucopyranoside (4), were isolated from the roots and rhizomes of Sinopodophyllum emodi together with one known lignan (5). Their structures and stereochemistry were elucidated on the basis of spectroscopic and mass spectrometric evidence. The isolation of compounds 1-5 represents the first report of tetrahydrofuran lignans from the genus Sinopodophyllum. The cytotoxic activities of all isolated compounds were evaluated against HeLa and KB cell lines, and compound 1 showed the most potent cytotoxicity with ICvalues of 9.7 μM and 4.7 μM, respectively.
- Sun, Yan-Jun,Li, Zhan-Lin,Chen, Hong,Liu, Xiao-Qiu,Zhou, Wei,Hua, Hui-Ming
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body text
p. 480 - 484
(2012/06/30)
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- Synthesis and characterization of new 5-linked pinoresinol lignin models
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Pinoresinol structures, featuring a β-β′-linkage between lignin monomer units, are important in softwood lignins and in dicots and monocots, particularly those that are downregulated in syringyl-specific genes. Although readily detected by NMR spectroscopy, pinoresinol structures largely escaped detection by β-ether-cleaving degradation analyses presumably due to the presence of the linkages at the 5 positions, in 5-5′- or 5-O-4′-structures. In this study, which is aimed at helping better understand 5-linked pinoresinol structures by providing the required data for NMR characterization, new lignin model compounds were synthesized through biomimetic peroxidase-mediated oxidative coupling reactions between pre-formed (free-phenolic) coniferyl alcohol 5-5′- or 5-O-4′-linked dimers and a coniferyl alcohol monomer. It was found that such dimers containing free-phenolic coniferyl alcohol moieties can cross-couple with the coniferyl alcohol producing pinoresinol-containing trimers (and higher oligomers) in addition to other homo- and cross-coupled products. Eight new lignin model compounds were obtained and characterized by NMR spectroscopy, and one tentatively identified cross-coupled β-O-4′-product was formed from a coniferyl alcohol 5-O-4′-linked dimer. It was demonstrated that the 5-5′- and 5-O-4′-linked pinoresinol structures could be readily differentiated by using heteronuclear multiple-bond correlation (HMBC) NMR spectroscopy. With appropriate modification (etherification or acetylation) to the newly obtained model compounds, it would be possible to identify the 5-5′- or 5-O-4′-linked pinoresinol structures in softwood lignins by 2D HMBCN MR spectroscopic methods. Identification of the cross-coupled dibenzodioxocin from a coniferyl alcohol 5-5′-linked moiety suggested that thioacidolysis or derivatization followed by reductive cleavage (DFRC) could be used to detect and identify whether the coniferyl alcohol itself undergoes 5-5′-cross-linking during lignification. Super model: In this study, aimed at helping to better understand 5-linked pinoresinol structures by providing the required data for NMR structural characterization, new lignin model pinoresinol compounds were synthesized through biomimetic peroxidase-mediated oxidative coupling between pre-formed (free-phenolic) 5-5′- or 5-O-4′-linked coniferyl alcohol dimers and a coniferyl alcohol monomer (examples with 5-O-4′-linked dimers are shown in the scheme).
- Yue, Fengxia,Lu, Fachuang,Sun, Runcang,Ralph, John
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supporting information
p. 16402 - 16410
(2013/02/23)
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- An enantiocomplementary dirigent protein for the enantioselective lacease-catalyzed oxidative coupling of phenols
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(+)- or (-)-plnoreslnol: that Is the question. Which of the two enantiomeric lignans is formed during laccasecatalyzed phenol coupling of (E)-coniferyl alcohol (1) depends on the dirigent protein. In the presence of the first enantiocomplementary dirigent protein AtDIR6, (-)-2 is formed (78 % ee). Preferential formation of (+)-2 is observed in the presence of the dirigent protein FiDIR1, whereas only racemic 2 is formed in the absence of dirigent proteins
- Pickel, Benjamin,Constantin, Mihaela-Anca,Pfannstiel, Jens,Conrad, Juergen,Beifuss, Uwe,Schaller, Andreas
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supporting information; experimental part
p. 202 - 204
(2010/03/30)
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- COMPOUND FEED FOR AQUACULTURE
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The present invention relates to a fish feed comprising dioxabicyclo[3.3.0]octane derivates, in particular selected sesame lignans, and a vegetable oil or oil mixture comprising at least one 18-carbon chain omega-3 fatty acid. The dioxabicyclo[3.3.0]octane derivate will induce a desaturation and elongation of the 18-carbon chain fatty acid in the fish muscle into longer carbon chain polyunsaturated fatty acids.
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- Lignin chemistry: Biosynthetic study and structural characterisation of coniferyl alcohol oligomers formed in vitro in a micellar environment
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Model coniferyl alcohol lignin (the so-called dehydrogenative Polymerisate, DHP) was produced in water under homogeneous conditions guaranteed by the presence of a micellised cationic surfactant. A complete study of the activity of the enzymatic system peroxidase/H2O2 under our reaction conditions was reported and all the reaction products up to the pentamer were characterised by 1H NMR spectroscopy and ESI mass spectrometry. Our system, and the molecules that have been generated in it, represent a closer mimicry of the natural microenvironment since an enzyme, under micellar conditions, reproduces the cell system better than in buffer alone. On the basis of the oligomers structures a new biosynthetic perspective was proposed that focused attention on a coni-feryl alcohol dimeric quinone methide as the key intermediate of the reaction. A formal, strictly alternate sequence of a radical and an ionic step underlines the reaction, thus generating ordered oligolignols structures. Alternatively to other model lignins, our olignols present a lower degree of radical coupling between oligomeric units. This offers a closer biosynthetic situation to the observation of a low rate of radical generation in the cell wall.
- Reale, Samantha,Attanasio, Francesca,Spreti, Nicoletta,De Angelis, Francesco
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experimental part
p. 6077 - 6087
(2010/09/11)
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- Arabidopsis peroxidase-catalyzed copolymerization of coniferyl and sinapyl alcohols: Kinetics of an endwise process
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In order to determine the mechanism of the earlier copolymerization steps of two main lignin precursors, sinapyl (S) alcohol and coniferyl (G) alcohol, microscale in vitro oxidations were carried out with a PRX34 Arabidopsis thaliana peroxidase in the presence of H2O2. This plant peroxidase was found to have an in vitro polymerization activity similar to the commonly used horseradish peroxidase. The selected polymerization conditions lead to a bulk polymerization mechanism when G alcohol was the only phenolic substrate available. In the same conditions, the presence of S alcohol at a 50/50 S/G molar ratio turned this bulk mechanism into an endwise one. A kinetics monitoring (size-exclusion chromatography and liquid chromatography-mass spectrometry) of the different species formed during the first 24 h oxidation of the S/G mixture allowed sequencing the bondings responsible for oligomerization. Whereas G homodimers and GS heterodimers exhibit low reactivity, the SS pinoresinol structure act as a nucleating site of the polymerization through an endwise process. This study is particularly relevant to understand the impact of S units on lignin structure in plants and to identify the key step at which this structure is programmed.
- Demont-Caulet, Nathalie,Lapierre, Catherine,Jouanin, Lise,Baumberger, Stéphanie,Méchin, Valérie
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experimental part
p. 1673 - 1683
(2011/02/27)
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- Hitherto unrecognized fluorescence properties of coniferyl alcohol
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We instituted a quasi-quality assurance program for demonstrating coniferyl alcohol's fluorescence and fluorescence diminishment following enzymatic oxidation. The magnitude of diminishment was a measure of catalysis. High throughput screening was performed in pseudo-kinetic and endpoint modes by measuring the fluorescence at 416 nm following excitation at 290, 310 or 340 nm. Dose-response tracings were linear between two and three orders of magnitude with average limits of detection and quantitation of 1.8 and 6.9 μM coniferyl alcohol, respectively. Oxidation was evident with 0.025 μg/mL laccase or 0.003 μg/mL peroxidase or inside 5 min using 0.5 μg/mL laccase or 5 μM substrate. Sodium chloride inhibited (IC50, 25 mM) laccase oxidation of coniferyl alcohol. Fluorescence from 10 concentrations (1 to 1000 μM) of coniferyl alcohol was stable for 24 hours over 14 excitation/emission cycles at 3 different combinations of excitation and emission wavelengths. In conclusion, coniferyl alcohol absorption and fluorescence assays should facilitate biomass lignin analyses and improve delignification.
- Achyuthan, Komandoor Elayavalli,Adams, Paul David,Datta, Supratim,Simmons, Blake Alexander,Singh, Anup Kumar
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experimental part
p. 1645 - 1667
(2010/06/13)
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- Low molecular weight lignin suppresses activation of NF-κB and HIV-1 promoter
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Human immunodeficiency virus type 1 (HIV-1) is a cytopathic retrovirus and the primary etiological agent of acquired immunodeficiency syndrome (AIDS) and related disorders. In cells chronically infected with HIV-1, nuclear factor-κB (NF-κB) activation by external stimuli such as tumor necrosis factor α (TNFα) augments replication of HIV-1. NF-κB involves in many diseases such as inflammation, cancer, and Crohn's disease. In this paper, we exhibit that (i) HIV-1gene expression was inhibited by lignin, (ii) fraction of small molecular mass in HBS lignin (less than 0.5 kDa) had stronger inhibitory effects than large molecular mass (more than 1.3 kDa), (iii) lignin also inhibited activation of NF-κB induced by TNFα, (iv) among six lignin dimer-like compounds, compound 6 containing β-5 bond has more potent inhibitory activity than compounds 1, 2, 3, 4 and 5, which contain β-1, β-O-4, 5-5, or β-β structural units. These results suggested that small molecules of lignin inhibit HIV-1 replication through suppression of HIV-1 transcription from LTR including activation via NF-κB. Low molecular lignin may be a beneficial material or drug leads as a new class for AIDS and NF-κB-related diseases.
- Mitsuhashi, Shinya,Kishimoto, Takao,Uraki, Yasumitsu,Okamoto, Takashi,Ubukata, Makoto
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p. 2645 - 2650
(2008/12/21)
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- Effect of the benzylic structure of lignan on antioxidant activity
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The effect of the benzylic structure of lignan on antioxidant activity was evaluated. Secoisolariciresinol (1) and 3,4-bis(4-hydroxy-3-methoxybenzyl) tetrahydrofuran (2), which have two secondary benzylic positions without oxygen, showed the highest antioxidant activity. Optically active verrucosin (4) was synthesized for the first time in this experiment.
- Yamauchi, Satoshi,Sugahara, Takuya,Matsugi, Junko,Someya, Tatsushi,Masuda, Toshiya,Kishida, Taro,Akiyama, Koichi,Maruyama, Masafumi
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p. 2283 - 2290
(2008/03/17)
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- A Versatile Stereoselective Synthesis of endo,exo-Furofuranones: Application to the Enantioselective Synthesis of Furofuran Lignans
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A new stereoselective route to endo,exo-2,6-diarylfurofuranones has been developed using Mn(III)-mediated intramolecular cyclopropanation and C-H insertion reactions as key C-C bond-forming steps. Mn(III)-mediated oxidative cyclization of acetoacetate derivative 11 afforded 1-acetyl-4-aryl-3-oxabicyclo[3.1.0]hexan-2-one (12) with excellent diastereocontrol (d.r. 22:1). Subsequent Lewis acid-catalyzed opening of the activated cyclopropane ring present in 12 with benzylic alcohols then gave α-acetyl-γ-butyrolactones 16 and 18-20, which reacted efficiently with in situ-generated TfN3 to secure the key α-diazo-γ -butyrolactones 22-25. Highly stereoselective rhodium-catalyzed C-H insertion reactions of diazolactones 22-25 completed the synthesis of endo,exo-2,6-diarylfurofuranones 26-29 in overall yields ranging from 41 to 48% from 1-phenylallyl alcohol (±)-10. The approach developed for the furofuranones 26-29 was then applied to the asymmetric syntheses of four furofuran lignans, (+)-xanthoxylol (1), (+)-methylxanthoxylol (2), (+)-epipinoresinol (3), and (+)-epieudesmin (4), starting from enantiomerically enriched 1-arylallyl alcohol (S)-31.
- Swain, Nigel A.,Brown, Richard C. D.,Bruton, Gordon
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p. 122 - 129
(2007/10/03)
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- Initial steps of the peroxidase-catalyzed polymerization of coniferyl alcohol and/or sinapyl aldehyde: Capillary zone electrophoresis study of pH effect
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Capillary zone electrophoresis has been used to monitor the first steps of the dehydrogenative polymerization of coniferyl alcohol, sinapyl aldehyde, or a mixture of both, catalyzed by the horseradish peroxidase (HRP)-H2O2 system. When coniferyl alcohol was the unique HRP substrate, three major dimers were observed (β-5, β-β, and β-O-4 interunit linkages) and their initial formation velocity as well as their relative abundance varied with pH. The β-O-4 interunit linkage was thus slightly favored at lower pH values. In contrast, sinapyl aldehyde turned out to be a very poor substrate for HRP except in basic conditions (pH 8). The major dimer observed was the β,β′-di-sinapyl aldehyde, a red-brown exhibiting compound which might partly participate in the red coloration usually observed in cinnamyl alcohol dehydrogenase-deficient angiosperms. Finally, when a mixture of coniferyl alcohol and sinapyl aldehyde was used, it looked as if sinapyl aldehyde became a very good substrate for HRP. Indeed, coniferyl alcohol turned out to serve as a redox mediator (i.e. shuttle oxidant ) for the sinapyl aldehyde incorporation in the lignin-like polymer. This means that in particular conditions the specificity of oxidative enzymes might not hinder the incorporation of poor substrates into the growing lignin polymer.
- Fournand, David,Cathala, Bernard,Lapierre, Catherine
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p. 139 - 146
(2007/10/03)
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- Short and stereoselective total synthesis of furano lignans (±)-dihydrosesamin, (±)-lariciresinol dimethyl ether, (±)-acuminatin methyl ether, (±)-sanshodiol methyl ether, (±)-lariciresinol, (±)-acuminatin, and (±)-lariciresinol
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Intramolecular radical cyclization of suitably substituted epoxy ethers 4a-g using bis(cyclopentadienyl)titanium(III) chloride as the radical source resulted in trisubstituted tetrahydrofurano lignans and 2,6-diaryl-3,7-dioxabicyclo [3.3.0] octane lignans depending on the reaction conditions. The titanium(III) species was prepared in situ from commercially available titanocene dichloride and activated zinc dust in THF. Upon radical cyclization followed by acidic workup, epoxy olefinic ethers 4a-g afforded furano lignans dihydrosesamin 1a, lariciresinol dimethyl ether lb, acuminatin methyl ether le, and sanshodiol methyl ether 1g directly and lariciresinol 1h, acuminatin li, and lariciresinol monomethyl ether 1j after removal of the benzyl protecting group by controlled hydrogenolysis of the corresponding cyclized products. The furofuran lignans sesamin 2a, eudesmin 2b, and piperitol methyl ether 2e were also prepared directly by using the same precursors 4a-f on radical cyclization followed by treatment with iodine and pinoresinol 2h, piperitol 2i, and pinoresinol monomethyl ether 2j after controlled hydrogenolysis of the benzyl protecting group of the corresponding cyclized products. Two naturally occurring acyclic lignans, secoisolariciresinol 5h and secoisolariciresinol dimethyl ether 5b, have also been prepared by exhaustive hydrogenolysis of 2h and 2b, respectively.
- Roy, Subhas Chandra,Rana, Kalyan Kumar,Guin, Chandrani
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p. 3242 - 3248
(2007/10/03)
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- Regioselectivity in oxidative cross-coupling of phenols. Application to the synthesis of dimeric neolignans
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The problems of regioselectivity in oxidative coupling of phenols are outlined, and recent research on the application to the synthesis of lignans and neolignans is reviewed. Lignans and neolignans are dimers that are typically formed by oxidative coupling of propenyl phenols. The coupling of structurally different phenols (cross-coupling) is an extension of this synthesis. Recent results show that cross-coupling can be achieved if the phenols have compatible reactivities. The regioselectivity is often quite different in cross-coupling compared to dimerization. Coupling of phenols with widely different rates of oxidation is difficult but can be achieved if the concentration of the more reactive phenol can be kept low enough during the reaction, for instance by diffusion through a dialysis membrane.
- Syrj?nen, Kaisa,Brunow, G?sta
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p. 365 - 370
(2007/10/03)
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- A new in vitro model of lignin biosynthesis
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A strictly coordinate sequence of radical and ionic steps appears to be the mechanism by which oligolignols are generated. A synthetic lignin was produced under micellar conditions [Eq. (1)], and the beginning of the polymerization process was studied by
- De Angelis, Francesco,Nicoletti, Rosario,Spreti, Nicoletta,Veri, Franca
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p. 1283 - 1285
(2007/10/03)
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- Oxidative cross coupling of p-hydroxycinnamic alcohols with dimeric arylglycerol β-aryl ether lignin model compounds. The effect of oxidation potentials
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Oxidation of p-hydroxycinnamyl alcohols together with dimeric lignin model compounds containing arylglycerol β-aryl ether structures was found, under certain conditions, to yield cross coupling products with β-aryl ether and 5,5′-biphenyl bonds. Cross cou
- Syrjaenen, Kaisa,Brunow, Goesta
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p. 3425 - 3429
(2007/10/03)
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- A SYNTHESIS OF (+/-)-PINORESINOL AND ITS RELATED COMPOUND USING POTASSIUM PERSULFATE (K2S2O8) OXIDATION OF BENZOYLACETATES
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A synthesis of (+/-)-pinoresinol has been accomplished by application of the oxidative coupling reaction of benzoylacetate with potassium persulfate as a key step.
- Maruyama, Jun,Kobayashi, Miho,Miyashita, Masaaki,Kouno, Isao,Irie, Hiroshi
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p. 839 - 846
(2007/10/02)
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- NOVEL BENZYLIC ETHER REDUCTIONS IN LIGNAN BIOGENESIS IN FORSYTHIA INTERMEDIA
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Forsythia intermedia cell-free preparations catalyse the stepwise conversion of pinoresinol into secoisolariciresinol via lariciresinol; to our knowledge, this represents the first documented example of the reduction of benzylic ethers (or their quinone methide analogues) in plants.In this study, the specifity of the reductive steps was established: with (+)- and (-)-pinoresinols as substrates, it was found that their overall conversion into lariciresinol was highly enantioselective (i.e > 99:1 in favour of the (+)-antipode), whereas (-)-secoisolariciresinol formation was more strictly enantioselective with only reduction of (+)-lariciresinol being observed.Under the conditions examined to date, it was not possible to demonstrate the NADP-dependent back reaction using (+/-)-lariciresinols as substrates.Interestingly, neither (+)- nor (-)-epipinoresinols underwent similar reduction to afford lariciresinol, epilariciresinol or secoisolariciresinol. Key Word Index - Forsythia; Oleaceae; biosynthesi; oxidoreductase; stereoselectivity; enantiospectifity; coniferyl alchols; lignans; lariciresinol; pinoresinol; secoisolaricireinol; epipinoresinol; quinone methide.
- Katayama, Takeshi,Davin, Laurence B.,Chu, Alex,Lewis, Norman G.
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p. 581 - 592
(2007/10/02)
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- Regio- and Diastereo-selective Synthesis of Dimeric Lignans Using Oxidative Coupling
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The oxidative dimerization of monolignols such as (E)-isoeugenol (1), (E)-methyl ferulate (2) and (E)-coniferyl alcohol (3) has been performed using two catalytic systems: horseradish peroxidase (HRP)-H2O2 and tetraphenylporphyrinatomanganese(III) acetate
- Chioccara, Francesco,Poli, Sonia,Rindone, Bruno,Pilati, Tullio,Brunow, Goesta,et al.
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p. 610 - 616
(2007/10/02)
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- Lignin-Feruloyl Ester Cross-links in Grasses. Part 2. Model Compound Syntheses
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Five compounds which model the various structures produced when feruloyl esters are copolymerized into lignins have been synthesized.These models represent the lignin-feruloyl-polysaccharide structures which have been theorized to exist in the Graminaceae but have yet to be isolated.Complete spectroscopic characterization provides important chemical-shift information to facilitate the identification of these linkages in native lignins and synthetic DHP polymers.Methyl 5-O-feruloyl>-α-L-arabinofuranoside, a model for the α-linkage of feruloyl esters to lignin, was prepared as a mixture of threo and erythro isomers by addition of methyl 5-O-(E)-feruloyl-α-L-arabinofuranoside (FA-Ara) to the quinone methide derived from 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol (guaiacylglycerol-β-guaiacyl ether).Methyl 5-O-feruloyl>-α-L-arabinofuranoside, a β-aryl ether model, was prepared by a method analogous to one used for the synthesis of guaiacylglycerol-β-guaiacyl ether; FA-Ara was added to 4-acetoxy-β-bromo-3-methoxyacetophenone, and the product was hydroxymethylated and reduced.The peracetate of methyl 5-O--α-L-arabinofuranoside, a compound which models the attack of lignin radicals on the β-position of the feruloyl ester, was prepared by elimination of the β-proton from the quinone methide derived from ethyl 3-hydroxy-3-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propanoate.As in the preparation of synthetic copolymers between coniferyl alcohol andFA-Ara, only a single geometrical isomer was produced.Synthesis of both isomers of derived compounds and detailed NMR analysis indicated that this was the expected Z-isomer.A model for β-5 coupled products, 3-acrylic acid bis(methyl 5-deoxy-α-L-arabinofuranosid-5-yl) ester, was obtained as a cis/trans mixture in 55percent yield by radical coupling of FA-Ara using silver(I) oxide.Finally, the crossed β-β-compound 4,8-exo-bis(4-hydroxy-3-methoxyphenyl)-3,7-dioxabicyclooctan-2-one (MEL) was obtained, in admixture with its isomer iso-MEL, pinoresinol, and the dilactone 4,8-exo-bis-(4-hydroxy-3-methoxyphenyl)-3,7-dioxabicyclooctan-2,6-dione, from mixed radical coupling of coniferyl alcohol and ferulic acid via silver(I) oxide.
- Ralph, John,Helm, Richard F.,Quideau, Stephane
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p. 2971 - 2980
(2007/10/02)
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- SYNTHESIS OF BIOLOGICALLY ACTIVE TETRAHYDROFUROFURANLIGNAN-(SYRINGIN, PINORESINOL)- MONO- AND BIS-GLYCOSIDES
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The naturally occuring tetrahydrofurofuran-lignan-(syringaresinol, pinoresinol)-mono- and bis-glucosides were synthesized and their structures thereby confirmed.Key Word Index - Ligan-glucosides; synthesis; syringaresinol and pinoresinol glucosides.
- Vermes, Barbara,Seligmann, Otto,Wagner, Hildebert
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p. 3087 - 3090
(2007/10/02)
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- Lignan Biosynthesis in Forsythia Species
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Both (+)-pinoresinol 6a in Forsythia suspensa and (-)-secoisolariciresinol 14a in F. intermedia are formed via a direct stereochemically-controlled coupling of coniferyl alcohol 2 derived moieties (cf. the typical peroxidase-catalysed reaction in the presence of H2O2), and the dibenzylbutyrolactone lignan, (-)-matairesinol 10a, in F. intermedia is formed from a post-coupling modification of (-)-secoisolariciresinol 14a; this transformation has been demonstrated in vivo, and in vitro with a crude enzyme preparation, and represents the first report of an enzyme specifically involved in lignan biosynthesis.
- Umezawa, Toshiaki,Davin, Laurence B.,Yamamoto, Etsuo,Kingston, David G. I.,Lewis, Norman G.
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p. 1405 - 1408
(2007/10/02)
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- LIGNAN GLYCOSIDES FROM PARSONSIA LAEVIGATA
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Bis-O-rhamnosides of lariciresinol, 5,5'-dimethoxylariciresinol, and secoisolariciresinol, and pinoresinolapiosyl(1->2)-glucoside were isolated from Parsonsia laevigata.Key Word Index - Parsonsia laevigata; Apocynaceae; lariciresinol; lignan rhamnoside; pinoresinol-apiosylglucoside.
- Abe, Fumiko,Yamauchi, Tatsuo
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p. 1737 - 1742
(2007/10/02)
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- VERSICOSIDE - A NEW LIGNAN GLYCOSIDE FROM Haplophyllum versicolor
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A new lignin glycoside has been isolated from Haplophyllum versicolor and has been called versicoside.It has been etablished by chemical and spectral methods that versicoside is (+)-epipinoresinol 4'-O-.
- Batirov, E. Kh.,Matkarimov, A. D.,Malikov, V. M.,Yagudaev, M. R.
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p. 584 - 587
(2007/10/02)
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- A LIGNAN FROM LONICERA HYPOLEUCA
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Key Word Index - Lonicera hypoleuca; Caprifoliaceae; lignan; 4-hydroxy-2,6-di(4'-hydroxy-3'-methoxy)phenyl-3,7-dioxabicyclo(3.3.0)octane; n-10-nonacosanol; scopoletin; syringic acid; sitosterol; β-sitosterol-β-D-glucoside; spasmolytic activity. - A new lignan characterised as (-)-4-hydroxy-2,6-di(4'-hydroxy-3'-methoxy)phenyl-3,7-dioxabicyclo(3.3.0)ocatane along with n-10-nonacosanol, scopoletin, syringic acid, β-sitosterol and its glucoside, has been isolated from the aerial parts of Lonicera hypoleuca.The stereochemistry of the lignan hasn been established by itsspectroscopic analysis and those of its derivatives, and by its conversion to (+)-pinoresinol. β-Sitosterol-β-D-glucoside displayed good spasmolitic activity.
- Khan, Khalid A.,Shoeb, Aboo
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p. 628 - 630
(2007/10/02)
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- Synthesis and 1H N.M.R. Spectroscopic Analysis of Some 3,7-Dioxabicyclooctane Lignans
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Within the framework of a synthetic project towards the preparation of the natural germination inhibitor 2,6-diaryl-3,7-dioxabicyclooctane, several molecules with the same bicyclic skeleton were prepared and their 1H n.m.r. spectra are described in detail.For the symmetrical systems particularly, the spectra exhibited second-order features and were interpreted analytically or, when necessary, by computer simulation.These n.m.r. data enabled a conformational analysis of the ring system.
- Velde, Vincent Vande,Lavie, David,Gottlieb, Hugo E.,Perold, Guido W.,Scheinmann, Feodor
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p. 1159 - 1164
(2007/10/02)
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- Effects of O-Methylation and O-Glucosylation on Carbon-13 Nuclear Magnetic Resonance Chemical Shifts of Matairesinol, (+)-Pinoresinol and (+)-Epipinoresinol
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The effects of O-methylation and O-glucosylation on the carbon-13 nuclear magnetic resonance chemical shifts of matairesinol (1), (+)-pinoresinol (6) and (+)-epipinoresinol (11) are discussed.The chemical shifts of carbons on the 2,3-dibenzylated butyrolactone and 2,6-diarylated 3,7-dioxabicyclooctane rings are not affected by methylation and glucosylation of hydroxy groups on the aromatic rings.As regards the chemical shifts of aromatic carbons caused by O-methylation, all the 1'(1''),3'(3''), and 4'(4'') carbons of the guaiacyl unit are characteristically shifted downfield by 1.6+/-0.1, 1.3+/-0.1, and 2.4+/-0.1 ppm, respectively, while the 5'(5'') carbons are shifted upfield by 3.5+/-0.1 ppm.In the case of the chemical shifts of aromatic carbons caused by O-glucosylation, all the 1'(1'')and 3'(3'') carbons of the guaiacyl unit are characteristically shifted downfield by 3.0+/-0.1 and 1.3+/-0.1 ppm, respectively.Keywords - 13C-NMR; O-methylation shift; O-glucosylation shift; ligan; matairesinol; (+)-pinoresinol; (+)-epipinoresinol; guaiacyl group
- Nishibe, Sansei,Tsukamoto, Hiroki,Hisada, Sueo
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p. 4653 - 4657
(2007/10/02)
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- The Constituents of Eucommia ulmoides OLIV. I. Isolation of (+)-Medioresinol Di-O-β-D-glucopyranoside
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A new lignan diglycoside was isolated from the bark of Eucommia ulmoides OLIV. (Eucommiaceae) and its structure was established as (+)-medioresinol di-O-β-D-glucopyranoside (1) by means of chemical and spectral studies. (+)-Pinoresinol di-O-β-D-glucopyranoside (2),liriodendrin (3) and (+)-pinoresinol O-β-D-glucopyranoside (4) were also isolated.Keywords - Eucommia ulmoides; lignan; (+)-medioresinol di-O-β-D-glucoside; (+)-pinoresinol di-O-β-D-glucoside; (+)-pinoresinol O-β-D-glucoside; liriodendrin; (13)C-NMR
- Deyama, Takeshi
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p. 2993 - 2997
(2007/10/02)
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- Synthesis of 2,6-Diaryl-4,8-dihydroxy-3,7-dioxabicyclooctanes
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A series of 2,6-diaryl-4,8-dihydroxy-3,7-dioxabicyclooctanes, including 4,8-dihydroxysesamin, a naturally occurring lignan, have been prepared via the corresponding dilactones.The 1H and 13C n.m.r. spectra have been compared and the bistoluene-p-sulphonate of 4,8-dihydroxyeudesmin has been reduced by lithium aluminium hydride to give (+/-)-eudesmin.Since this synthesis does not involve ring-opened intermediates and starts from a dilactone of established structure, it represents the first unequivocal synthesis of such a lignan.
- Pelter, Andrew,Ward, Robert S.,Watson, Derrick J.,Collins, Peter,Kay, I. Trevor
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p. 175 - 182
(2007/10/02)
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