Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/4/1997
Publication Date: N/A
Citation: Interpretive Summary: A major component in all terrestrial plants, lignin is a polymer that limits digestion of plants by animals and must be removed from wood to make paper. We recently developed a new analytical method, the "DFRC" method (for Derivatization Followed by Reductive Cleavage, but also identifying the Dairy Forage Research Center where it was developed) that cleanly degrades lignins to simple analyzable compounds that give insight into the structural details of the original lignin. This paper reports on the identification of a range of dimers (products obtained from coupling of two lignin basic units during its biosynthesis) that gives us a picture of how the lignin was built up in the plant. The identifications described in this paper pave the way for an analytical method to quantify these dimers. Scientists will use this technique in a wide variety of studies ranging from optimization of pulping processes in pulp mills to the identification of how a plant responds to various genetic mutations that are forced on it Such studies are at the heart of efforts to improve agricultural sustainability and maximize our plant resources.
Technical Abstract: Fourteen lignin dimers were directly isolated from large-scale DFRC- degraded loblolly pine (Pinus taeda L.) sapwood by gel permeation and reversed-phase TLC and HPLC. Their structures were elucidated by GC-MS and NMR. These dimers include beta-1, beta-beta, 5-5, beta-5, beta-6 and 5-O-4 units. All but one are guaiacyl-guaiacyl dimers (from coniferyl alcohol- derived units in lignin); a small amount of a p-hydroxyphenyl/guaiacyl bet 1 dimer was characterized. Several dimers have benzaldehydes as one unit; since aldehydes are not created by the procedure, they are either present in the native lignin or are formed during the (minimal) preparation of the wood. The dimers isolated and identified here will eventually allow their quantitation to aid in structural analyses of wide-ranging plant materials.