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Verschoor JA, Baird MS, Grooten J. Towards understanding the functional diversity of cell wall mycolic acids of Mycobacterium tuberculosis. Prog Lipid Res 2012; 51:325-39. [PMID: 22659327 DOI: 10.1016/j.plipres.2012.05.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 03/05/2012] [Accepted: 05/23/2012] [Indexed: 01/08/2023]
Abstract
Mycolic acids constitute the waxy layer of the outer cell wall of Mycobacterium spp. and a few other genera. They are diverse in structure, providing a unique chromatographic foot-print for almost each of the more than 70 Mycobacterium species. Although mainly esterified to cell wall arabinogalactan, trehalose or glucose, some free mycolic acid is secreted during in vitro growth of Mycobacterium tuberculosis. In M. tuberculosis, α-, keto- and methoxy-mycolic acids are the main classes, each differing in their ability to attract neutrophils, induce foamy macrophages or adopt an antigenic structure for antibody recognition. Of interest is their particular relationship to cholesterol, discovered by their ability to attract cholesterol, to bind Amphotericin B or to be recognised by monoclonal antibodies that cross-react with cholesterol. The structural elements that determine this diverse functionality include the carboxylic acid in the mycolic motif, as well as the nature and stereochemistry of the two functional groups in the merochain. The functional diversity of mycolic acid classes implies that much information may be contained in the selective expression and secretion of mycolic acids to establish tuberculosis after infection of the host. Their cholesteroid nature may relate to how they utilize host cholesterol for their persistent survival.
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Vander Beken S, Al Dulayymi JR, Naessens T, Koza G, Maza-Iglesias M, Rowles R, Theunissen C, De Medts J, Lanckacker E, Baird MS, Grooten J. Molecular structure of the Mycobacterium tuberculosis virulence factor, mycolic acid, determines the elicited inflammatory pattern. Eur J Immunol 2010; 41:450-60. [PMID: 21268014 DOI: 10.1002/eji.201040719] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 10/20/2010] [Accepted: 11/17/2010] [Indexed: 11/12/2022]
Abstract
Mycolic acids (MAs) occur in the cell wall of Mycobacterium tuberculosis as variable mixtures of different classes and chain lengths. Here, we address the relationship between the structure and its inflammatory function of this virulence factor using single synthetic MA isomers, differing in oxygenation class and cis- versus α-methyl-trans proximal cyclopropane orientation. Analysis of bronchoalveolar inflammation, lung histopathology and alveolar macrophage transcription revealed a strong dependence on these meromycolic chemistries of mouse pulmonary inflammation in response to intratracheal treatments with MAs. Whereas α-MA was inert, oxygenated methoxy- and keto-MA with cis-cyclopropane stereochemistry elicited solid to mild inflammatory responses respectively. In trans-cyclopropane orientation, methoxy-MA partially lost its inflammatory activity and keto-MA exerted anti-inflammatory alternative activation of alveolar macrophages and counteracted cis-methoxy-MA induced airway inflammation. The differential innate immune activities of MAs demonstrated here, dependent on oxygenation class and cis versus α-methyl-trans cyclopropane chemistry, identify a novel means for M. tuberculosis to steer host immune responses during infection.
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Beukes M, Lemmer Y, Deysel M, Al Dulayymi JR, Baird MS, Koza G, Iglesias MM, Rowles RR, Theunissen C, Grooten J, Toschi G, Roberts VV, Pilcher L, Van Wyngaardt S, Mathebula N, Balogun M, Stoltz AC, Verschoor JA. Structure-function relationships of the antigenicity of mycolic acids in tuberculosis patients. Chem Phys Lipids 2010; 163:800-8. [PMID: 20875402 PMCID: PMC3025329 DOI: 10.1016/j.chemphyslip.2010.09.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 09/14/2010] [Accepted: 09/17/2010] [Indexed: 11/17/2022]
Abstract
Cell wall mycolic acids (MA) from Mycobacterium tuberculosis (M.tb) are CD1b presented antigens that can be used to detect antibodies as surrogate markers of active TB, even in HIV coinfected patients. The use of the complex mixtures of natural MA is complicated by an apparent antibody cross-reactivity with cholesterol. Here firstly we report three recombinant monoclonal scFv antibody fragments in the chicken germ-line antibody repertoire, which demonstrate the possibilities for cross-reactivity: the first recognized both cholesterol and mycolic acids, the second mycolic acids but not cholesterol, and the third cholesterol but not mycolic acids. Secondly, MA structure is experimentally interrogated to try to understand the cross-reactivity. Unique synthetic mycolic acids representative of the three main functional classes show varying antigenicity against human TB patient sera, depending on the functional groups present and on their stereochemistry. Oxygenated (methoxy- and keto-) mycolic acid was found to be more antigenic than alpha-mycolic acids. Synthetic methoxy-mycolic acids were the most antigenic, one containing a trans-cyclopropane apparently being somewhat more antigenic than the natural mixture. Trans-cyclopropane-containing keto- and hydroxy-mycolic acids were also found to be the most antigenic among each of these classes. However, none of the individual synthetic mycolic acids significantly and reproducibly distinguished the pooled serum of TB positive patients from that of TB negative patients better than the natural mixture of MA. This argues against the potential to improve the specificity of serodiagnosis of TB with a defined single synthetic mycolic acid antigen from this set, although sensitivity may be facilitated by using a synthetic methoxy-mycolic acid.
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Muzael M, Koza G, Dulayymi JJA, Baird MS. The synthesis of a major α′-mycolic acid of Mycobacterium smegmatis. Chem Phys Lipids 2010; 163:678-84. [DOI: 10.1016/j.chemphyslip.2010.05.203] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2010] [Revised: 05/19/2010] [Accepted: 05/26/2010] [Indexed: 10/19/2022]
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Driver CH, Balogun MO, Toschi G, Verschoor JA, Baird MS, Pilcher LA. A biomimetic approach to the synthesis of a mycolic acid motif. Tetrahedron Lett 2010. [DOI: 10.1016/j.tetlet.2009.12.105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Sheshenev AE, Baird MS, Bolesov IG, Shashkov AS. Stereo- and regiocontrol in ene-dimerisation and trimerisation of 1-trimethylsilyl-3-phenylcyclopropene. Tetrahedron 2009. [DOI: 10.1016/j.tet.2009.10.077] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Koza G, Rowles R, Theunissen C, Al-Dulayymi JR, Baird MS. The synthesis of single enantiomers of trans-alkene-containing mycolic acids. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.10.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Sheshenev AE, Baird MS, Croft AK, Bolesov IG. Generation and stereoselective transformations of 3-phenylcyclopropene. Tetrahedron 2009. [DOI: 10.1016/j.tet.2009.09.098] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Gratraud P, Huws E, Falkard B, Adjalley S, Fidock DA, Berry L, Jacobs WR, Baird MS, Vial H, Kremer L. Oleic acid biosynthesis in Plasmodium falciparum: characterization of the stearoyl-CoA desaturase and investigation as a potential therapeutic target. PLoS One 2009; 4:e6889. [PMID: 19707292 PMCID: PMC2731242 DOI: 10.1371/journal.pone.0006889] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 08/05/2009] [Indexed: 01/16/2023] Open
Abstract
Background Plasmodium falciparum parasitization of erythrocytes causes a substantial increase in the levels of intracellular fatty acids, notably oleic acid. How parasites acquire this monounsaturated fatty acid has remained enigmatic. Here, we report on the biochemical and enzymatic characterization of stearoyl-CoA desaturase (SCD) in P. falciparum. Methodology/Principal Findings Metabolic labeling experiments allowed us to demonstrate the production of oleic acid from stearic acid both in lysates of parasites incubated with [14C]-stearoyl-CoA and in parasite-infected erythrocytes labeled with [14C]-stearic acid. Optimal SCD activity was detected in schizonts, the stage of maximal membrane synthesis. This activity correlated with a late trophozoite stage-specific induction of PFE0555w transcripts. PFE0555w harbors a typical SCD signature. Similar to mammalian SCDs, this protein was found to be associated with the endoplasmic reticulum, as determined with PFE0555w-GFP tagged transgenic P. falciparum. Importantly, these parasites exhibited increased rates of stearic to oleic acid conversion, providing additional evidence that PFE0555w encodes the plasmodial SCD (PfSCD). These findings prompted us to assess the activity of sterculic acid analogues, known to be specific Δ9-desaturase inhibitors. Methyl sterculate inhibited the synthesis of oleic acid both with parasite lysates and infected erythrocytes, most likely by targeting PfSCD. This compound exhibited significant, rapid and irreversible antimalarial activity against asexual blood stages. This parasiticidal effect was antagonized by oleic acid. Conclusion/Significance Our study provides evidence that parasite-mediated fatty acid modification is important for blood-stage survival and provides a new strategy to develop a novel antimalarial therapeutic based on the inhibition of PfSCD.
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Al Dulayymi JR, Baird MS, Maza-Iglesias M, Beken SV, Grooten J. The first unique synthetic mycobacterial cord factors. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.03.213] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Benadie Y, Deysel M, Siko DGR, Roberts VV, Van Wyngaardt S, Thanyani ST, Sekanka G, Ten Bokum AM, Collett LA, Grooten J, Baird MS, Verschoor JA. Cholesteroid nature of free mycolic acids from M. tuberculosis. Chem Phys Lipids 2008; 152:95-103. [DOI: 10.1016/j.chemphyslip.2008.01.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 12/23/2007] [Accepted: 01/28/2008] [Indexed: 10/22/2022]
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Baird MS. Functionalised cyclopropenes as synthetic intermediates. Top Curr Chem (Cham) 2007. [DOI: 10.1007/bfb0111230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
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Baird MS, Boitsov VM, Stepakov AV, Molchanov AP, Kopf J, Rajaratnam M, Kostikov RR. Preparation and reactions of some 2,2-difunctional 1,1-dibromocyclopropanes. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.04.104] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Al Dulayymi JR, Baird MS, Roberts E, Deysel M, Verschoor J. The first syntheses of single enantiomers of the major methoxymycolic acid of Mycobacterium tuberculosis. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.01.007] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Al Dulayymi JR, Baird MS, Roberts E, Minnikin DE. The synthesis of single enantiomers of meromycolic acids from mycobacterial wax esters. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.09.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Liu CF, Xu F, Sun JX, Ren JL, Curling S, Sun RC, Fowler P, Baird MS. Physicochemical characterization of cellulose from perennial ryegrass leaves (Lolium perenne). Carbohydr Res 2006; 341:2677-87. [PMID: 16934239 DOI: 10.1016/j.carres.2006.07.008] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2006] [Revised: 07/03/2006] [Accepted: 07/13/2006] [Indexed: 11/24/2022]
Abstract
In this study, we investigated the physicochemical properties of the cellulosic preparations obtained from both untreated perennial ryegrass leaves and de-juiced leaves. It was found that treatment at 22 degrees C with 18% NaOH and 18% KOH for 2h, and 10% NaOH and 10% KOH for 16 h yielded 28.2%, 28.8%, 22.7%, 23.4%, respectively, of 'cellulose' residue from untreated ryegrass leaves and 35.7%, 36.8%, 32.8% and 34.6%, respectively, from the de-juiced leaves. For each cellulosic fraction, the glucose content was 71.6%, 69.6%, 67.8%, 66.7%, 69.7%, 68.6%, 63.9% and 61.7%, respectively. The structure of the cellulose samples was examined using FTIR and CP/MAS (13)C NMR spectroscopy and X-ray diffraction. The cellulosic preparations were free of bound lignin except for noticeable amounts of residual hemicelluloses (28.4-38.3%), and had intrinsic viscosities between 275.1 and 361.0 mL/g, along with molecular weights from 144,130 to 194,930 g/mol. This study found that the cellulose samples isolated from both de-juiced ryegrass leaves and the untreated leaves had a much lower percent crystallinity (33.0-38.6%) than that from wood-based fibres (60-70%) and had much shorter fibres (0.35-0.49 mm) than those of either cereal straws, bagasse or wood. In addition, a partial disruption of the hydrogen bonds and microfibrils may occur during the de-juicing process by mechanical activity, which results in a decreased cellulose crystallinity and fibre length. These findings are significant in relation to hydrolysing ryegrass cellulose for bio-ethanol production.
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Xu F, Geng ZC, Sun JX, Liu CF, Ren JL, Sun RC, Fowler P, Baird MS. Fractional and structural characterization of hemicelluloses from perennial ryegrass (Lolium perenne) and cocksfoot grass (Dactylis glomerata). Carbohydr Res 2006; 341:2073-82. [PMID: 16750181 DOI: 10.1016/j.carres.2006.04.033] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2006] [Revised: 04/06/2006] [Accepted: 04/19/2006] [Indexed: 11/16/2022]
Abstract
Sequential three-stage treatments with 80% EtOH containing 0.2% NaOH, 2.5% H2O2-0.2% EDTA containing 1.5% NaOH and 2.5% H2O2-0.2% TAED containing 1.0% NaOH at 75 degrees C for 3h released 8.0% and 10.4%, 79.1% and 77.0% and 12.9% and 12.5% of the original hemicelluloses from perennial grass and cocksfoot grass, respectively. It was found that the four alkaline peroxide-soluble hemicellulosic fractions contained higher amounts of xylose (33.4-38.2%), uronic acids (9.3-15.3%) and rhamnose (3.0-3.9%), but were lower in glucose (25.1-28.3%), galactose (13.3-15.3%) and mannose (0.4-1.5%) than those of the two alkaline EtOH-soluble hemicellulosic fractions in which glucose (32.9-36.0%), xylose (20.1-22.6%), arabinose (14.1-21.4%), galactose (16.6-19.9%), mannose (4.1-9.9%) and uronic acids (3.4-7.4%) were the major sugar components. 13C NMR spectroscopy confirmed that all the six hemicellulosic fractions were composed of galactoarabinoxylans, 4-O-methylglucuronoarabinoxylans and beta-glucan. In addition, the studies showed that the four alkaline peroxide-soluble hemicellulosic fractions were more linear and acidic and had larger molecular weights (Mw, 28,400-38,650 g mol(-1)) than those of the two alkaline EtOH-soluble hemicellulosic fractions (Mw, 16,460-17,420 g mol(-1)).
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Al-Dulayymi JR, Baird MS, Mohammed H, Roberts E, Clegg W. The synthesis of one enantiomer of the α-methyl-trans-cyclopropane unit of mycolic acids. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.03.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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45
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Toschi G, Baird MS. An improved procedure for the preparation of the β-hydroxy-α-alkyl fatty acid fragment of mycolic acids. Tetrahedron 2006. [DOI: 10.1016/j.tet.2006.01.070] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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46
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Sheshenev AE, Baird MS, Croft AK, Starikova ZA, Shashkov AS, Zhuze AL, Bolesov IG. Stereocontrol in ene-dimerisation and trimerisation of 1-trimethylsilyl-3-phenylcyclopropene. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2005.12.111] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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47
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Roberts IO, Baird MS. A new short synthesis of 10R-tuberculostearic acid and its enantiomer. Chem Phys Lipids 2006; 142:111-7. [PMID: 16690044 DOI: 10.1016/j.chemphyslip.2006.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2005] [Revised: 03/11/2006] [Accepted: 03/16/2006] [Indexed: 11/21/2022]
Abstract
Tuberculostearic acid (10R-methyloctadecanoic acid) and its 10S-enantiomer were synthesised by a chiral pool strategy, in four steps from citronellyl bromide.
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Al Dulayymi JR, Baird MS, Roberts E. The synthesis of a single enantiomer of a major α-mycolic acid of M. tuberculosis. Tetrahedron 2005. [DOI: 10.1016/j.tet.2005.09.056] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Sun XF, Xu F, Zhao H, Sun RC, Fowler P, Baird MS. Physicochemical characterisation of residual hemicelluloses isolated with cyanamide-activated hydrogen peroxide from organosolv pre-treated wheat straw. BIORESOURCE TECHNOLOGY 2005; 96:1342-1349. [PMID: 15792581 DOI: 10.1016/j.biortech.2004.11.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2004] [Revised: 10/18/2004] [Accepted: 11/16/2004] [Indexed: 05/24/2023]
Abstract
Seven residual hemicellulosic preparations (19.6-45.0% of the original hemicelluloses) were extracted from wheat straw pre-treated with various organic solvents using 1.8% H2O2-0.18% cyanamide at 50 degrees C and pH 10.0 for 4 h. Their chemical compositions and physicochemical properties were determined using GC, HPLC, GPC, FT-IR and 13NMR spectroscopy. The results indicated that all the residual hemicellulosic preparations were heteropolysaccharides containing xylose, glucose, arabinose, galactose, mannose, rhamnose and 4-O-methyl-alpha-D-glucopyranosyluronic acid. The predominant monosaccharide was xylose, ranging between 67.7% and 81.9% of the total neutral sugars, composed mainly of L-arabino-(4-O-methyl-D-glucurono)-D-xylan. The content of contaminant lignin in the isolated residual hemicelluloses was 2.89-5.31%. The Mw values of the two residual hemicellulosic preparations H6 and H7 (42,710 and 44,080 g mol-1, respectively) obtained from the aqueous-alcohol pre-treated straw were much higher than those of H1-H5 (12,980-15,950 g mol-1) extracted from the organic acid pre-treated straw.
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Sun XF, Sun R, Fowler P, Baird MS. Extraction and characterization of original lignin and hemicelluloses from wheat straw. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2005; 53:860-70. [PMID: 15712990 DOI: 10.1021/jf040456q] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Original lignin and hemicelluloses were sequentially extracted with high yield/purity, using acidic dioxane/water solution and dimethyl sulfoxide, from ball-milled wheat straw. The acidic dioxane lignin fraction is distinguished by high beta-O-4' structures and by low amounts of condensed units (beta-5', 5-5', and beta-1'). Hemicelluloses contain arabinoxylans as the major polysaccharides, which are substituted by alpha-l-arabinofuranose, 4-O-methylglucuronic acid, acetyl group (DS = 0.1), and xylose at O-3 and/or O-2 of xylans. It was found that arabinoxylans form cross-links with lignins through ferulates via ether bonds, glucuronic acid via ester bonds, and arbinose/xylose via both ether and glycosidic bonds, respectively, in the cell walls of wheat straw. Diferulates are also incorporated into cross-links between lignin and hemicelluloses as well as lignification of wheat straw cell walls. The guaiacyl unit is considered to be a significant condensed structural constructor in extracted lignin and a connector between lignin and carbohydrates.
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