p-Hydroxybenzoate groups in the lignin of aspen (populus tremula)

Smith, Donald C.

doi:10.1039/jr9550002347

Cited by 83 publications

(54 citation statements)

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“…The lower absorption coefficient of hardwood MWL at 280nm, as compared to softwood MWL, is attributed to the presence of syringyl groups in the former lignin (9, 10). In hardwoods, lignins show a high absorption coefficient (maximum values in hardwood MWL in Table I), which is attributed to the p-hydroxybenzoate groups in the lignins (13).…”

Section: Chemical Composition Of Exwlmentioning

confidence: 99%

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Characterization of aspen exploded wood lignin

Marchessault¹,

Coulombe²,

Morikawa³

et al. 1982

Can. J. Chem.

114

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Exploded wood lignin (EXWL) was extracted from moist steam hydrolysed aspen (Populustremuloides) wood using methanol. The lignin was examined by elemental analysis, gel permeation chromatography, infrared spectroscopy, proton and 13C nmr. The observed nmr spectra were compared with those of aspen milled wood lignin (MWL). Typical composition of the material is C9H9.2O2.7(OCH3)1.1 Assignment of all the signals in the nmr spectrum led to the conclusion that the explosion process causes cleavage of the β-aryl-ether bond. The weight average molecular weight was found to be 1700–1900 and the polydispersity 2.6. The finely divided exploded wood was soluble in 90% methanol/water mixtures to well beyond 20% by weight at room temperature.

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Section: Chemical Composition Of Exwlmentioning

confidence: 99%

“…The relative intensities of the unconjugated carbony1 bands in aspen EXWL were higher (about two times) than in the aspen MWL (6,13). Based on differential infrared spectra of lignins in woods and pulps, Bolker (15,19) has shown that unconjugated P-ketone groups in isolated lignins are formed during solvolytic isolation.…”

Section: Chemical Composition Of Exwlmentioning

confidence: 99%

Characterization of aspen exploded wood lignin

Marchessault¹,

Coulombe²,

Morikawa³

et al. 1982

Can. J. Chem.

114

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“…The lignin of grasses is adorned with g-p-coumarate substituents on a variety of lignin units. Lignin structural analyses of poplar, aspen, willow, and palm have shown that g-p-hydroxybenzoate esters are present (Smith, 1955;Nakano et al, 1961;Sun et al, 1999;Meyermans et al, 2000;Landucci and Ralph, 2001). The fact that only S units are g-p-hydroxybenzoylated in both poplar lignin and the oligolignol fraction supports the contention that sinapyl p-hydroxybenzoate is produced enzymatically and used as an authentic monomer for lignification in poplar.…”

Section: Sinapyl P-hydroxybenzoates Are Precursors In Lignin Biosynthmentioning

confidence: 99%

Profiling of Oligolignols Reveals Monolignol Coupling Conditions in Lignifying Poplar Xylem

et al. 2004

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Lignin is an aromatic heteropolymer, abundantly present in the walls of secondary thickened cells. Although much research has been devoted to the structure and composition of the polymer to obtain insight into lignin polymerization, the lowmolecular weight oligolignol fraction has escaped a detailed characterization. This fraction, in contrast to the rather inaccessible polymer, is a simple and accessible model that reveals details about the coupling of monolignols, an issue that has raised considerable controversy over the past years. We have profiled the methanol-soluble oligolignol fraction of poplar (Populus spp.) xylem, a tissue with extensive lignification. Using liquid chromatography-mass spectrometry, chemical synthesis, and nuclear magnetic resonance, we have elucidated the structures of 38 compounds, most of which were dimers, trimers, and tetramers derived from coniferyl alcohol, sinapyl alcohol, their aldehyde analogs, or vanillin. All structures support the recently challenged random chemical coupling hypothesis for lignin polymerization. Importantly, the structures of two oligomers, each containing a g-p-hydroxybenzoylated syringyl unit, strongly suggest that sinapyl p-hydroxybenzoate is an authentic precursor for lignin polymerization in poplar.

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“…Poplar wood specifically contains p-hydroxybenzoic esters linked to lignin units (Smith, 1955). Alkaline hydrolysis of extract-free samples was performed to determine the impact of the transformation on this acylation.…”

Section: Analysis Of Low-m R Phenolics Released By Mild Alkaline Hydrmentioning

confidence: 99%

Structural Alterations of Lignins in Transgenic Poplars with Depressed Cinnamyl Alcohol Dehydrogenase or Caffeic AcidO-Methyltransferase Activity Have an Opposite Impact on the Efficiency of Industrial Kraft Pulping1

et al. 1999

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We evaluated lignin profiles and pulping performances of 2-yearold transgenic poplar (Populus tremula ؋ Populus alba) lines severely altered in the expression of caffeic acid/5-hydroxyferulic acid O-methyltransferase (COMT) or cinnamyl alcohol dehydrogenase (CAD). Transgenic poplars with CAD or COMT antisense constructs showed growth similar to control trees. CAD downregulated poplars displayed a red coloration mainly in the outer xylem. A 90% lower COMT activity did not change lignin content but dramatically increased the frequency of guaiacyl units and resistant biphenyl linkages in lignin. This alteration severely lowered the efficiency of kraft pulping. The Klason lignin level of CAD-transformed poplars was slightly lower than that of the control. Whereas CAD down-regulation did not change the frequency of labile ether bonds or guaiacyl units in lignin, it increased the proportion of syringaldehyde and diarylpropane structures and, more importantly with regard to kraft pulping, of free phenolic groups in lignin. In the most depressed line, ASCAD21, a substantially higher content in free phenolic units facilitated lignin solubilization and fragmentation during kraft pulping. These results point the way to genetic modification of lignin structure to improve wood quality for the pulp industry.

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p-Hydroxybenzoate groups in the lignin of aspen (populus tremula)

Cited by 83 publications

References 0 publications

Characterization of aspen exploded wood lignin

Characterization of aspen exploded wood lignin

Profiling of Oligolignols Reveals Monolignol Coupling Conditions in Lignifying Poplar Xylem

Structural Alterations of Lignins in Transgenic Poplars with Depressed Cinnamyl Alcohol Dehydrogenase or Caffeic AcidO-Methyltransferase Activity Have an Opposite Impact on the Efficiency of Industrial Kraft Pulping1

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