- The Conjugated Double Bond of Coniferyl Aldehyde Is Essential for Heat Shock Factor 1 Mediated Cytotoprotection
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Coniferyl aldehyde (1) is previously reported as a potent inducer of heat shock factor 1 (HSF1). Here, we further examined the active pharmacophore of 1 for activation of HSF1 using the derivatives coniferyl alcohol (2), 4-hydroxy-3-methoxyphenylpropanal (3), and 4-hydroxy-3-methoxyphenylpropanol (4). Both 1 and 2 resulted in increased survival days after a lethal radiation (IR) dose. The decrease in bone marrow (BM) cellularity and Ki67-positive BM cells by IR was also significantly restored by 1 or 2 in mice. These results suggested that the vinyl moiety of 1 and 2 is necessary for inducing HSF1, which may be useful for developing small molecules for cytoprotection of normal cells against damage by cytotoxic drugs and radiation.
- Choi, Seul-Ki,Mun, Gil-Im,Choi, Eun,Kim, Seo-Young,Kwon, Youngjoo,Na, Younghwa,Lee, Yun-Sil
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Read Online
- Paving the Way for the Lignin Hydrogenolysis Mechanism by Deuterium-Incorporated β-O-4 Mimics
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Gaining more insight into the lignin hydrogenolysis mechanism is of great importance for developing next-generation catalysts and regulating product distribution because lignin is the only renewable aromatic source leading to aromatic chemicals. However, the inherent complexity of the lignin structure and the multiple pathways in lignin hydrogenolysis make gaining insight into the lignin hydrogenolysis mechanism even more challenging. In this report, a β-O-4 polymer with deuterium incorporated at the α, β, and γpositions which can better model the plant lignin structure was prepared for mechanistic study. The location and retention of deuterium in the monomers resulting from the hydrogenolysis and transfer hydrogenolysis of the deuterated β-O-4 mimics with Ru/C, Pd/C, and Pd/Zn/C in MeOH indicated that the β-O-4 linkage protons did not participate in the cleavage process, which indicated that pathways involving dehydrogenation and/or dehydration reactions are infeasible for these catalysts under these conditions. A concerted process, wherein the Cα-O and Cβ-O bonds in β-O-4 structures were cleaved concurrently, was proposed as a potential hydrogenolysis mechanism in the Pd/C and Ru/C systems. Dehydroxylation at the α position was identified as a side reaction in the Pd/C-catalyzed hydrogenolysis of dimer models, from which the same concurrent cleavage mechanism was also inferred. The introduction of a Lewis acid center in Pd/C was conducive to β-O-4 hydrogenolysis, as confirmed by the abatement of the side reaction and the enhanced monomer yield in the polymeric model reactions. The use of deuterium-incorporated β-O-4 mimics paved the way for clearly elucidating the lignin hydrogenolysis mechanism.
- Li, Helong,Song, Guoyong
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Read Online
- Controlled lignosulfonate depolymerization: Via solvothermal fragmentation coupled with catalytic hydrogenolysis/hydrogenation in a continuous flow reactor
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Sodium lignosulfonate (LS) was valorized to low molecular weight (Mw) fractions by combining solvothermal (SF) and catalytic hydrogenolysis/hydrogenation fragmentation (SHF) in a continuous flow system. This was achieved in either alcohol/H2O (EtOH/H2O or MeOH/H2O) or H2O as a solvent and Ni on nitrogen-doped carbon as a catalyst. The tunability according to the temperature of both SF and catalytic SHF of LS has been separately investigated at 150 °C, 200 °C, and 250 °C. In SF, the minimal Mw was 2994 g mol-1 at 250 °C with a dispersity (?) of 5.3 using MeOH/H2O. In catalytic SHF using MeOH/H2O, extremely low Mw was found (433 mg gLS-1) with a ? of 1.2 combined with 34 mg gLS-1. The monomer yield was improved to 42 mg gLS-1 using dual catalytic beds. These results provide direct evidence that lignin is an unstable polymer at elevated temperatures and could be efficiently deconstructed under hydrothermal conditions with and without a catalyst. This journal is
- Al-Naji, Majd,Antonietti, Markus,Brandi, Francesco
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supporting information
p. 9894 - 9905
(2021/12/24)
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- Non-plasmonic Ni nanoparticles catalyzed visible light selective hydrogenolysis of aryl ethers in lignin under mild conditions
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Light-driven catalysis on catalytically versatile group VIII metals, which has been widely used in thermal catalysis, holds great potential in solar-to-chemical conversion. We report a novel photocatalysis process for the selective hydrogenolysis of aryl ethers in lignin on a heterogeneous catalyst of non-precious Ni nanoparticles supported on ZrO2. Three aryl ether bonds in lignin were successfully cleaved under mild conditions with excellent conversion and good to excellent selectivity under visible light irradiation. We also used solar irradiation to demonstrate a significant reduction in the total energy consumption. The light irradiation excited interband transitions in Ni nanoparticles and the resultant energetic electrons enhanced the activity of reductive cleavage of the aryl ethers. Its application potential was illustrated by the depolymerization of dealkaline lignin to give a total monomer yield of 9.84 wt% with vanillin, guaiacol, and apocynin as the three major products.
- Baeyens, Jan,Li, Peifeng,Ouyang, Yixuan,Sarina, Sarina,Su, Haijia,Xiao, Gang,Zhao, Yilin,Zhu, Huai-Yong
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supporting information
p. 7780 - 7789
(2021/10/12)
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- Scope and limitations of biocatalytic carbonyl reduction with white-rot fungi
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The reductive activity of various basidiomycetous fungi towards carbonyl compounds was screened on an analytical level. Some strains displayed high reductive activities toward aromatic carbonyls and aliphatic ketones. Utilizing growing whole-cell cultures of Dichomitus albidofuscus, the reactions were up-scaled to a preparative level in an aqueous system. The reactions showed excellent selectivities and gave the respective alcohols in high yields. Carboxylic acids were also reduced to aldehydes and alcohols under the same conditions. In particular, benzoic, vanillic, ferulic, and p-coumaric acid were reduced to benzyl alcohol, vanillin, dihydroconiferyl alcohol and 1-hydroxy-3-(4-hydroxyphenyl)propan, respectively.
- Zhuk, Tatyana S.,Skorobohatko, Oleksandra S.,Albuquerque, Wendell,Zorn, Holger
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supporting information
(2021/02/02)
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- METHOD OF FORMING MONOMERS AND FURFURAL FROM LIGNOCELLULOSE
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The present disclosure relates to a method of producing monophenolicmonomers and furfural from lignocellulosic biomass beating the biomass in a solvent together with a zeolite based catalyst.
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Page/Page column 19; 21; 22
(2020/06/05)
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- Biocatalytic reduction of α,β-unsaturated carboxylic acids to allylic alcohols
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We have developed robust in vivo and in vitro biocatalytic systems that enable reduction of α,β-unsaturated carboxylic acids to allylic alcohols and their saturated analogues. These compounds are prevalent scaffolds in many industrial chemicals and pharmaceuticals. A substrate profiling study of a carboxylic acid reductase (CAR) investigating unexplored substrate space, such as benzo-fused (hetero)aromatic carboxylic acids and α,β-unsaturated carboxylic acids, revealed broad substrate tolerance and provided information on the reactivity patterns of these substrates. E. coli cells expressing a heterologous CAR were employed as a multi-step hydrogenation catalyst to convert a variety of α,β-unsaturated carboxylic acids to the corresponding saturated primary alcohols, affording up to >99percent conversion. This was supported by the broad substrate scope of E. coli endogenous alcohol dehydrogenase (ADH), as well as the unexpected CC bond reducing activity of E. coli cells. In addition, a broad range of benzofused (hetero)aromatic carboxylic acids were converted to the corresponding primary alcohols by the recombinant E. coli cells. An alternative one-pot in vitro two-enzyme system, consisting of CAR and glucose dehydrogenase (GDH), demonstrates promiscuous carbonyl reductase activity of GDH towards a wide range of unsaturated aldehydes. Hence, coupling CAR with a GDH-driven NADP(H) recycling system provides access to a variety of (hetero)aromatic primary alcohols and allylic alcohols from the parent carboxylates, in up to >99percent conversion. To demonstrate the applicability of these systems in preparative synthesis, we performed 100 mg scale biotransformations for the preparation of indole-3-aldehyde and 3-(naphthalen-1-yl)propan-1-ol using the whole-cell system, and cinnamyl alcohol using the in vitro system, affording up to 85percent isolated yield.
- Aleku, Godwin A.,Leys, David,Roberts, George W.
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p. 3927 - 3939
(2020/07/09)
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- Chemodivergent hydrogenolysis of eucalyptus lignin with Ni@ZIF-8 catalyst
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Reductive catalytic fractionation (RCF) of lignocellulosic biomass, that is depolymerization of the native lignin component into well-defined monomeric phenols in the first step, offers an opportunity to utilize entire biomass components. Herein, we report that Ni@ZIF-8 can serve as a chemodivergent catalyst in RCF of eucalyptus sawdust, thus selectively producing phenolic compounds having either a propyl or propanol end-chain under different reaction conditions. In both cases, high yields of lignin monomers and a high degree of delignification were achieved, next to well-preserved carbohydrate pulp suitable for further processing. A mechanistic study using model compounds indicated that the dehydroxylation at the γ-position of the β-O-4 structure may be involved in the selectivity-controlling step.
- Liu, Xue,Li, Helong,Xiao, Ling-Ping,Sun, Run-Cang,Song, Guoyong
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supporting information
p. 1498 - 1504
(2019/03/26)
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- High Yield Production of Natural Phenolic Alcohols from Woody Biomass Using a Nickel-Based Catalyst
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Efficient depolymerization of woody biomass to produce natural phenolic alcohols not only preserves the original structure of lignin, but also makes the depolymerization process atom-efficient. Here, high yield production of natural phenolic alcohols (38.7 wt %) from woody biomass has been achieved using a Ni/C catalyst in a methanol–water co-solvent. The Ni-based catalyst can efficiently etherify the Cα?OH group in lignin β-O-4 motifs under hydrogen atmosphere, which can break the hydrogen bond between the Cβ?O oxygen and the Cα?OH proton to facilitate the Cβ?O cleavage. It was reported that water can also accelerate the etherification of raw lignin with methanol through in situ formation of acid. Our results suggest that breaking the intramolecular hydrogen bonds can accelerate the Cβ?O cleavage, keeping the original structure of lignin unchanged. This work highlights the significance of structure modification in lignin depolymerization and displays a clear potential for the valorization of whole biomass.
- Chen, Jiazhi,Lu, Fang,Si, Xiaoqin,Nie, Xin,Chen, Junsheng,Lu, Rui,Xu, Jie
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p. 3353 - 3360
(2016/12/16)
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- Mechanistic investigation of the Zn/Pd/C catalyzed cleavage and hydrodeoxygenation of lignin
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While current biorefinery processes use lignin only for its heat value, the conversion of lignin to high value chemicals is an area of increasing interest. Herein we present a detailed mechanistic study of the hydrodeoxygenation (HDO) of lignin by using a synergistic Pd/C and ZnII catalyst through use of both lignin model compounds and lignocellulosic biomass. Spectroscopic data coupled with the study of lignin model compounds suggest that ZnII activates and facilitates removal of the hydroxyl group at the Cγ position of the β-O-4 ether linkage. Activation is proposed to occur through formation of a six-membered ring complex of ZnII coordinated to the oxygen atoms at Cα and Cγ of the lignin model compound guaiacylglycerol-β-guaiacyl.
- Klein, Ian,Marcum, Christopher,Kentt?maa, Hilkka,Abu-Omar, Mahdi M.
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p. 2399 - 2405
(2016/05/19)
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- Exploring the synthetic applicability of a new carboxylic acid reductase from Segniliparus rotundus DSM 44985
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A new carboxylic acid reductase (CAR) gene from Segniliparus rotundus DSM 44985 was overexpressed in Escherichia coli. The recombinant enzyme exhibited high activity toward a variety of aromatic and aliphatic carboxylic acids. Especially, it effectively reduced 4-hydroxybenzoic acid (8a) and 4-nitrobenzoic acid (19a), toward which the known Nocardia CAR exhibited no or little activity. The recombinant E. coli cells co-expressing the Segniliparus CAR and Nocardia PPTase genes catalyzed the reductions of vanillic acid (20a) and 3,4-dihydroxyphenylacetic acid (25a) to give vanillyl alcohol (20c) and 3-hydroxytyrosol (25c) with high yield, respectively. The endogenous aldehyde reductases of E. coli should be responsible for the further reduction of the produced aldehydes. These results demonstrated that Segniliparus CAR was a useful addition to the biocatalyst tool-box for the reduction of carboxylic acids and might find applications in the synthesis of valuable bio-based chemicals from renewable resources.
- Duan, Yitao,Yao, Peiyuan,Chen, Xi,Liu, Xiangtao,Zhang, Rui,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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- A diastereoselective route to trans-2-aryl-2,3-dihydrobenzofurans through sequential cross-metathesis/isomerization/allylboration reactions: Synthesis of bioactive neolignans
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A new highly diastereoselective synthetic route to trans-2,3-dihydrobenzofuran systems, in particular those bearing an aryl substituent at the C2 position, is described. The cornerstone of our strategy is the implementation of a cross-metathesis/isomerization/allylboration sequence starting from 2-allyl-substituted phenols and aldehydes. After an intramolecular Mitsunobu cyclization step, the anti-homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol (1a), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O-demethylated derivative 1b. An enantioselective version of this approach employing a chiral phosphoric acid in the allylboration step is also studied.
- Hemelaere, Rémy,Carreaux, Fran?ois,Carboni, Bertrand
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supporting information
p. 2470 - 2481
(2015/04/22)
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- One-Pot Defunctionalization of Lignin-Derived Compounds by Dual-Functional Pd50Ag50/Fe3O4/N-rGO Catalyst
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Generation of hydrogen from renewable sources and its safe utilization for efficient one-pot upgrading of renewable biofuels are a challenge. Bimetallic PdAg catalyst supported on Fe3O4/nitrogen-doped reduced graphene oxide (N-rGO) were synthesized for hydrogen generation from formic acid with high TOF (497 h-1 at 50 °C), and the hydrogen was subsequently utilized in situ for selective defunctionalization of lignin-derived chemicals with preserved aromatic nature at ambient pressure. Hydrodeoxygenation of aromatic aldehydes and ketones gave excellent yields (99% at 130 °C) with no use of additives. Furthermore, hydrogenolysis of β-O-4 and α-O-4 C-O model compounds produced only two products with high selectivity at 120 °C, which is an efficient and versatile one-pot platform for valorization of lignin biomass.
- Singh, Ajay K.,Jang, Seungwook,Kim, Jae Yul,Sharma, Siddharth,Basavaraju,Kim, Min-Gyu,Kim, Kyung-Rok,Lee, Jae Sung,Lee, Hong H.,Kim, Dong-Pyo
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p. 6964 - 6972
(2015/11/18)
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- A biocompatible alkene hydrogenation merges organic synthesis with microbial metabolism
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Organic chemists and metabolic engineers use orthogonal technologies to construct essential small molecules such as pharmaceuticals and commodity chemicals. While chemists have leveraged the unique capabilities of biological catalysts for small-molecule production, metabolic engineers have not likewise integrated reactions from organic synthesis with the metabolism of living organisms. Reported herein is a method for alkene hydrogenation which utilizes a palladium catalyst and hydrogen gas generated directly by a living microorganism. This biocompatible transformation, which requires both catalyst and microbe, and can be used on a preparative scale, represents a new strategy for chemical synthesis that combines organic chemistry and metabolic engineering. Reduction to practice: A hydrogenation reaction has been developed that employs hydrogen generated in situ by a microorganism and a biocompatible palladium catalyst to reduce alkenes on a synthetically useful scale. This type of transformation, which directly combines tools from organic chemistry with the metabolism of a living organism for small-molecule production, represents a new strategy for chemical synthesis.
- Sirasani, Gopal,Tong, Liuchuan,Balskus, Emily P.
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supporting information
p. 7785 - 7788
(2014/08/05)
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- Cleavage and hydrodeoxygenation (HDO) of C-O bonds relevant to lignin conversion using Pd/Zn synergistic catalysis
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The development of chemical methods for the direct catalytic conversion of biomass to high value organic molecules is an area of increasing interest. The plant matter component known as lignin is a polymer consisting of aromatic rings that could provide a means of obtaining aromatic materials currently derived solely from petroleum. This report describes a bimetallic Pd/C and Zn catalytic system that can perform selective hydrodeoxygenation (HDO) of monomeric lignin surrogates as well as successfully cleave the β-O-4 linkages found in dimeric lignin model complexes and synthetic lignin polymers with near quantitative conversions and yields between 80-90%. The reaction with lignin polymer was highly selective affording methoxy substituted propylphenol as the major product. These reactions were performed in a Parr reactor operating at relatively mild temperature (150 °C) and pressure (20 bar H2) using methanol as a solvent. Reaction products were characterized using high-pressure liquid chromatography coupled to a linear quadrupole ion trap mass spectrometer equipped with an electrospray ionization source using negative ion mode. Hydroxide ions were doped into the analyte solutions to encourage negative ion formation. This method ionizes all the mixture components to yield a single ion/analyte with no fragmentation. The catalyst is fully recyclable without the need for additional zinc. X-ray absorption spectroscopy (EXAFS) is consistent with Pd nanoparticles (4-5 nm) and no evidence of Pd-Zn alloy formation. A mechanistic hypothesis on the synergy between Pd and Zn is presented. The Royal Society of Chemistry 2013.
- Parsell, Trenton H.,Owen, Benjamin C.,Klein, Ian,Jarrell, Tiffany M.,Marcum, Christopher L.,Haupert, Laura J.,Amundson, Lucas M.,Kenttaemaa, Hilkka I.,Ribeiro, Fabio,Miller, Jeffrey T.,Abu-Omar, Mahdi M.
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p. 806 - 813
(2013/03/28)
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- Catalytic conversion of biomass using solvents derived from lignin
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We report an approach by which the hemicellulose and cellulose fractions of biomass are converted through catalytic processes in a solvent prepared from lignin into high value platform chemicals and transportation fuels, namely furfural, 5-hydroxymethylfurfural, levulinic acid and γ-valerolactone. The Royal Society of Chemistry.
- Azadi, Pooya,Carrasquillo-Flores, Ronald,Pagan-Torres, Yomaira J.,Guerbuez, Elif I.,Farnood, Ramin,Dumesic, James A.
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supporting information
p. 1573 - 1576
(2013/02/23)
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- DEPOLYMERIZATION OF LIGNIN USING SOLID ACID CATALYSTS
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The invention provides for a process for the depolymerization of lignin in an inert atmosphere to result in substituted phenolic monomer compounds. The process is catalysed by heterogeneous solid acid catalysts and is carried out in batch or continuous mode.
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Page/Page column 6; 7
(2012/12/13)
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- Pinus taeda phenylpropenal double-bond reductase: Purification, cDNA cloning, heterologous expression in Escherichia coli, and subcellular localization in P. taeda
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A phenylpropenal double-bond reductase (PPDBR) was obtained from cell suspension cultures of loblolly pine (Pinus taeda L.). Following trypsin digestion and amino acid sequencing, the cDNA encoding this protein was subsequently cloned, with the functional recombinant protein expressed in Escherichia coli and characterized. PPDBR readily converted both dehydrodiconiferyl and coniferyl aldehydes into dihydrodehydrodiconiferyl and dihydroconiferyl aldehydes, when NADPH was added as cofactor. However, it was unable to reduce directly either the double bond of dehydrodiconiferyl or coniferyl alcohols in the presence of NADPH. During this reductive step, the corresponding 4-proR hydrogen was abstracted from [4R-3H]-NADPH during hydride transfer. This is thus the first report of a double-bond reductase involved in phenylpropanoid metabolism, and which is presumed to be involved in plant defense. In situ mRNA hybridization indicated that the PPDBR transcripts in P. taeda stem sections were localized to the vascular cambium, as well as to radial and axial parenchyma cell types. Additionally, using P. taeda cell suspension culture crude protein extracts, dehydrodiconiferyl and coniferyl alcohols could be dehydrogenated to afford dehydrodiconiferyl and coniferyl aldehydes. Furthermore, these same extracts were able to convert dihydrodehydrodiconiferyl and dihydroconiferyl aldehydes into the corresponding alcohols. Taken together, these results indicate that in the crude extracts dehydrodiconiferyl and coniferyl alcohols can be converted to dihydrodehydrodiconiferyl and dihydroconiferyl alcohols through a three-step process, i.e. by initial phenylpropenol oxidation, then sequential PPDBR and phenylpropanal reductions, respectively.
- Kasahara, Hiroyuki,Jiao, Ying,Bedgar, Diana L.,Kim, Sung-Jin,Patten, Ann M.,Xia, Zhi-Qiang,Davin, Laurence B.,Lewis, Norman G.
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p. 1765 - 1780
(2008/02/12)
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- Benzo[f][1,2]oxasilepines in the synthesis of dihydro[b]benzofuran neolignans
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A short synthesis of neolignans with a dihydrobenzo[b]furan skeleton is described. The strategy is based on a ring-closing metathesis to produce benzo[f][1,2]oxasilepines which are condensed with aromatic aldehydes in a modified Sakurai-Hosomi reaction. Natural dihydrodehydrodiconiferyl alcohol (1) and 3-O-demethyldihydrodehydrodiconiferyl alcohol (2) have been prepared in this way. Georg Thieme Verlag Stuttgart.
- García-Mu?oz, Sergio,Jiménez-González, Leticia,álvarez-Corral, Míriam,Mu?oz-Dorado, Manuel,Rodríguez-García, Ignacio
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p. 3011 - 3013
(2007/10/03)
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- Methoxyphenols from burning of Scandinavian forest plant materials
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Semivolatile compounds in smoke from gram-scale incomplete burning of plant materials were assessed by gas chromatography and mass spectrometry. Gas syringe sampling was shown to be adequate by comparison with adsorbent sampling. Methoxyphenols as well as 1,6-anhydroglucose were released in amounts as large as 10 mg kg-1 of dry biomass at 90% combustion efficiency. Wood, twigs, bark and needles from the conifers Norway spruce and Scots pine emitted 12 reported 2-methoxyphenols in similar proportions. Grass, heather and birchwood released the same 2-methoxyphenols but also the corresponding 2,6-dimethoxyphenols which are characteristic of angiosperms. The methoxyphenols are formed from lignin and differ in structure by the group in para position relative to the phenolic OH group. Prominent phenols were those with trans-l-propenyl and ethenyl groups in that position. Vanillin, 4- hydroxy-3-methoxybenzaldehyde, was a prominent carbonyl compound from the conifer materials. (C) 2000 Elsevier Science Ltd.
- Kjaellstrand, Jennica,Ramnaes, Olle,Petersson, Goeran
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p. 735 - 741
(2007/10/03)
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- Selective protection of either the phenol or the hydroxy group in hydroxyalkyl phenols
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Hydroxyalkyl phenols can be protected either at the hydroxy group or at the phenol in a simple protocol (CH2Cl2, Et3N, DMAP, 0 °C → room temp.) by using either t-butyldimethylsilyl chloride or trityl chloride as protecting reagent. Yields are in the range of 37-92%.
- Sefkow, Michael,Kaatz, Helvi
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p. 6561 - 6562
(2007/10/03)
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- A new synthesis of the benzofuran adenosine antagonist XH-14
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5-(3-Hydroxypropyl)-7-methoxy-2-(3'-methoxy-4'-hydroxyphenyl)benzo[b]furan-3 -carbaldehyde (XH-14, 1) has been reported to be a potent A1 adenosine antagonist. We have developed an efficient synthesis of this compound that should prove valuable for further structure-activity studies. The synthesis incorporates optimised methodology for the selective protection of a hydroxyl group and the ortho-bromination of a phenol.
- Hutchinson, Sally A.,Luetjens, Henning,Scammells, Peter J.
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p. 3081 - 3084
(2007/10/03)
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- ENDOGENEOUS PINE WOOD NEMATICIDAL SUBSTANCES IN PINES, PINUS MASSONIANA, P. STROBUS AND P. PALUSTRIS
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The presence of the repellents and nematicides to the pine wood nematode, Bursaphelenchus xylophilus, was found in the heartwood and bark of Pinus massoniana, P. strobus and P. palustris, which have a resistance to the pine wood nematode.The heartwood of P. massoniana contained a repellent, α-humulene and two nematicidal substances, pinosylvin monomethylether (PMS) and (-)-nortrachelogenin for the nematode.The bark of the pine contained two nematicides, methyl ferulate and (+)-pinoresinol.PMS, which showed the highest nematicidal activity (LD 50 was 4 ppm), was also contained in the heartwood of P. strobus and the heartwood and bark of P. palustris.The resistance of these pines to the pine wood nematode is considered to be attributed to the presence of these endogenously defending substances.Further, the relationship between the structure and the nematicidal activity was elucidated for PSM and methyl ferulate.Moreover, PSM showed little anti-acetylcholinesterase activity.
- Suga, Takayuki,Ohta, Shinji,Munesada, Kiyotaka,Ide, Nagatoshi,Kurokawa, Masako,et al.
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p. 1395 - 1402
(2007/10/02)
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- CINNAMIC ACID BRIDGES BETWEEN CELL WALL POLYMERS IN WHEAT AND PHALARIS INTERNODES
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A method has been devised for the quantitative determination of cinnamic acids participating in ester-ether bridges between cell wall polymers based on the different reactivities of free carboxylic acids and their esters towards borohydride reductants and the different susceptibilities of cinnamic acid ester and benzyl ether linkages to alkaline treatments.Lignin-poylsaccharide containing fractions extracted with dioxane-H2O from cell walls of wheat (Triticum aestivum) and phalaris (phalaris aquatica) internodes are hydrogenated using a Pd/C catalyst at room temperature to convert cinnamic acids to their corresponding dihydrocinnamic acids.The sample is subsequently reduced with LiBH4 in ether-toluene to convert ester-linked dihydrocinnamates to their corresponding alcohols, hydrolysed with 4 M NaOH at 170 deg, and the dihydrocinnamic acid derivatives released from their etherified forms determined by GC.Using model compounds it was shown that these reactions proceeded quantitatively.The results indicate that all of the etherified ferulic acid in the dioxane-H2O-soluble fractions of walls of wheat and phalaris internodes is also ester-linked.It has been calculated that there are nine to 10 ferulic acid ester-ether bridges for every 100 C6-C3 lignin monomers. p-Coumaric acid is not involved in ester-ether bridges. Key Word Index - Triticum aestivum; Phalaris aquatica; Gramineae; lignin; polysaccharide; p-coumaric acid; ferulic acid; esterified cinnamic acid; etherified cinnamic acid.
- Lam, Thi Bach Tuyet,Iiyama, Kenji,Stone, Bruce A.
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p. 1179 - 1184
(2007/10/02)
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- PHENOLIC COMPOUNDS FROM ROOTS OF URTICA DIOICA
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Root extracts from Urtica dioica were separated into several classes of compounds by extraction with organic solvents at different pH values.The phenolic fraction was analysed by GC-MS after trimethylsilylation.This procedure allowed the identification of 18 phenolic compounds as well as the detection of eight lignans.The occurrence of some of these substances in this plant was previously unknown.
- Kraus, Rupert,Spiteller, Gerhard
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p. 1653 - 1659
(2007/10/02)
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- IMPROVED PROCEDURE FOR THE REDUCTION OF ESTERS TO ALCOHOLS BY SODIUM BOROHYDRIDE
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An improved procedure for the employment of NaBH4 in the reduction of ester function is described.
- Bianco, A.,Passacantilli, P.,Righi, G.
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p. 1765 - 1772
(2007/10/02)
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- OLEFIN SATURATION AND ACID REDUCTION OF 3,4-DIMETHOXYCINNAMIC ACID AND DERIVATIVES BY PHANEROCHAETE CHRYSOSPORIUM
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The white rot fungus Phanerochaete chrysosporium metabolized 3,4-dimethoxycinnamic acid in shaking and nitrogen sufficient cultures.Metabolites identified included 3-(3,4-dimethoxyphenyl)propionic acid, dimethoxycinnamyl alcohol and 3-(3,4-dimethoxyphenyl)-1-propanol.Significantly smaller amounts of veratryl and vanillyl alcohol were also present.The abundance of the propionic acid and the propanol as metabolic products indicate that olefin saturation and acid reduction are important reactions catalysed under these conditions.Metabolites identified from the metabolism of 3-(3,4-dimethoxyphenyl)-propionic acid included the above 1-propanol as well as veratryl and vanillyl alcohol; the identification of these benzyl alcohol derivatives as metabolites suggests that α,β-bond cleavage of this substrate was preceded by alkane hydroxylation at the α-position.Key Word Index-Phanerochaete chrysosporium; basidiomycete; dimethoxycinnamic acid; ferulic acid; veratryl alcohol; acid reduction; olefin saturation; metabolism
- Enoki, Akio,Yajima, Yasuo,Gold, Michael H.
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p. 1543 - 1546
(2007/10/02)
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- Synthesis of Coniferyl and Dihydroconiferyl Derivatives Using Radical Bromination with N-Bromosuccinimide as the Key Step
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Coniferyl and dihydroconiferyl derivatives have been synthesized by reacting bromides, obtained from allylic and benzylic brominations using N-bromosuccinimide (NBS), with appropriate nucleophiles.For instance, NBS bromination of eugenol acetate, followed by replacement of bromine by an acetoxy group and subsequent reduction with lithium aluminium hydride, afforded coniferyl alcohol in 65percent overall yield.Due to the availability of the starting materials (eugenol and isoeugenol) and the good overall yields obtained, these synthetic routes compete well with other methods of preparation.
- Lindeberg, Otto
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