Structural characterization of wheat straw lignin. Evidence for a novel monomer in grasses.
The structure of the lignin in wheat straw has been investigated by 2D-NMR and DFRC. It is a p-hydroxyphenyl-guaiacyl-syringyl lignin (with a H:G:S ratio of 6:64:30) associated with p-coumarates and ferulates. The main substructures present are β–O–4´-ethers (~75%), followed by phenylcoumarans (~11%), with lower amounts of other units. The lignin is partially acylated (~10%) at the γ-carbon, predominantly with acetates that preferentially acylate guaiacyl (12%) rather than syringyl (1%) units. p-Coumarate esters were barely detectable (<1%) on monomer conjugates released by selectively cleaving β-ethers in DFRC, indicating that they might be preferentially involved in condensed or terminal structures. A major new finding is that the flavone tricin is apparently incorporated into the lignins.
| Main Authors: | , , , , , |
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| Format: | comunicación de congreso biblioteca |
| Language: | English |
| Published: |
2013-06-12
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| Subjects: | Wheat straw, Milled wood lignin, HSQC, DFRC, p-Coumarates, Tricin, |
| Online Access: | http://hdl.handle.net/10261/86427 |
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| Summary: | The structure of the lignin in wheat straw has been investigated by 2D-NMR and DFRC. It is a p-hydroxyphenyl-guaiacyl-syringyl lignin (with a H:G:S ratio of 6:64:30) associated with p-coumarates and ferulates. The main substructures present are β–O–4´-ethers (~75%), followed by phenylcoumarans (~11%), with lower amounts of other units. The lignin is partially acylated (~10%) at the γ-carbon, predominantly with acetates that preferentially acylate guaiacyl (12%) rather than syringyl (1%) units. p-Coumarate esters were barely detectable (<1%) on monomer conjugates released by selectively cleaving β-ethers in DFRC, indicating that they might be preferentially involved in condensed or terminal structures. A major new finding is that the flavone tricin is apparently incorporated into the lignins. |
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