New Preparations of Lignin Polymer Models under Conditions that Approximate Cell Wall Lignification. I. Synthesis of Novel Lignin Polymer Models and their Structural Characterization by <sup>
                     <b>13</b>
                  </sup>C NMR

Terashima, Noritsugu; Atalla, R.H.; Ralph, Sally A.; Landucci, Larry L.; Lapierre, Catherine; Monties, Bernard

doi:10.1515/hfsg.1995.49.6.521

Cited by 89 publications

(70 citation statements)

References 12 publications

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“…[8,[9][10][11][12][13] C 2 ]-coniferyl alcohol was finally obtained using diisobutylaluminium hydride (10 eq.) at 0°C, as described previously , as pale-yellow crystals in quantitative yield; simultaneous phenolic deacetylation also occurs during the reduction (Terashima et al, 1995). 1 H-NMR (d 6 -acetone, 500 MHz): d 3.76 (1H, m, H-9-OH), 3.85 (3H,s,OMe),4.18 (2H,dddd,J = 140.2,10.2,5.5,1.6 Hz,6.21 (1H,ddtd,J = 150.7,15.9,5.4,4.2 Hz,6.48 (1H,ddt,J = 15.9,7.0,1.7 Hz, H-7), 6.76 (1H, d, J = 8.1 Hz, H-5), 6.85 (1H, dd, J = 8.1, 1.9 Hz, H-6), 7.05 (1H, d, J = 1.9 Hz, H-2), 7.62 (1H, s, phenol-OH).…”

Section: Synthesismentioning

confidence: 78%

Small Glycosylated Lignin Oligomers Are Stored in Arabidopsis Leaf Vacuoles

et al. 2015

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Lignin is an aromatic polymer derived from the combinatorial coupling of monolignol radicals in the cell wall. Recently, various glycosylated lignin oligomers have been revealed in Arabidopsis thaliana. Given that monolignol oxidation and monolignol radical coupling are known to occur in the apoplast, and glycosylation in the cytoplasm, it raises questions about the subcellular localization of glycosylated lignin oligomer biosynthesis and their storage. By metabolite profiling of Arabidopsis leaf vacuoles, we show that the leaf vacuole stores a large number of these small glycosylated lignin oligomers. Their structural variety and the incorporation of alternative monomers, as observed in Arabidopsis mutants with altered monolignol biosynthesis, indicate that they are all formed by combinatorial radical coupling. In contrast to the common believe that combinatorial coupling is restricted to the apoplast, we hypothesized that the aglycones of these compounds are made within the cell. To investigate this, leaf protoplast cultures were cofed with 13 C 6 -labeled coniferyl alcohol and a 13 C 4 -labeled dimer of coniferyl alcohol. Metabolite profiling of the cofed protoplasts provided strong support for the occurrence of intracellular monolignol coupling. We therefore propose a metabolic pathway involving intracellular combinatorial coupling of monolignol radicals, followed by oligomer glycosylation and vacuolar import, which shares characteristics with both lignin and lignan biosynthesis.

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Section: Synthesismentioning

confidence: 78%

Small Glycosylated Lignin Oligomers Are Stored in Arabidopsis Leaf Vacuoles

et al. 2015

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“…In the context of this work, a particular G-DHP (III) was cho sen because it had a high concentration of coniferyl alcohol end groups. A detailed structural 13 C NMR com parison of III with loblolly pine MWL has been published (Terashima et al 1995). The aim of the present study was to check the applicability of the Raman analysis, based on the CsC stretch mode band, in direct comparison to the same sample analyzed by 13 C NMR.…”

Section: Quantification Of Coniferyl Alcohol Units In G-dhp (Iii)mentioning

confidence: 97%

“…G-DHP (III) was a gift from Professor Noritsugu Terashima. The DHP was produced from coniferin by means of the enzymes b-glucosidase and peroxidase (Terashima et al 1995). The MWL isolation is reported elsewhere (Agarwal and Ralph 1997).…”

Section: Lignin Models G-dhp and Mwlmentioning

confidence: 99%

Determination of ethylenic residues in wood and TMP of spruce by FT-Raman spectroscopy

Agarwal

Ralph

2008

HFSG

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A method based on FT-Raman spectroscopy is proposed for determining in situ concentrations of ethylenic resi dues in softwood lignin. Raman contributions at 1133 and 1654 cm -1 , representing coniferaldehyde and coni feryl alcohol structures, respectively, were used in quan tifying these units in spruce wood with subsequent conversion to concentrations in lignin. For coniferalde hyde units, the intensity of the 1133 cm -1 peak was measured in the difference spectrum obtained by sub tracting the bleached-wood spectrum from that of the unbleached. In the case of coniferyl alcohol residues, the intensity of the 1654 cm -1 band was calculated from the spectrum of extensively bleached wood. The concentra tions of coniferaldehyde and coniferyl alcohol units in spruce lignin were found to be 3.8% and 3.4%, respec tively, and were in good agreement with values deter mined by conventional techniques. This quantification of the ethylenic residues was based on the Raman inten sities of 1% coniferaldehyde and 1% coniferyl alcohol in bleached softwood kraft pulp. Initially, as background for this work, a number of suitable lignin model compounds and a softwood lignin model polymer (G-DHP) were used to calibrate the Raman method and demonstrate that the Raman technique was well suited for quantification of ethylenic structures. Experimental results demonstrated that thermomechanical pulping reduced the concentra tions of coniferaldehyde and coniferyl alcohol residues in comparison to wood by 28% and 24%, respectively.

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“…The wall matrix may influence the formation of lignin. For example, synthetic lignins (dehydrogenation polymers [DHPs]) synthesized in the presence of polysaccharides have different bond distributions than simple in vitro DHPs (Terashima et al, 1995). Also, if we examine the DHP produced using isolated corn cell walls with active peroxidases, the linkage pattern is nearly the same as that observed in native lignins isolated from the stems of corn (Grabber, et al, 1996).…”

Section: The Random Coupling Modelmentioning

confidence: 99%