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ARS Home » Midwest Area » Madison, Wisconsin » U.S. Dairy Forage Research Center » Research » Publications at this Location » Publication #123839
Title: PROOF THAT NATIVE LIGNIN ACETYLATION IN KENAF OCCURS AT THE MONOLIGNOL STAGE

Author
item LU, FACHUANG - DFRC
item Ralph, John

Submitted to: Meeting Abstract
Publication Type: Proceedings
Publication Acceptance Date: 6/11/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Many lignins are naturally acylated, but whether acylation occurs at the monolignol stage (prior to lignification) or post-lignification has not been unambiguously determined. Here we elucidate the pathway for acetylation in kenaf. Derivatization followed by reductive cleavage, the "DFRC" method for lignin analysis, can be modified by replacing all acetyl reagents and solvents with their propionyl analogs. This DFRC' method, combined with GC-MS, then allows the analysis of naturally acetylated lignins. When sinapyl acetate is oxidized alone or with sinapyl alcohol by H2O2/peroxidase, novel coupled or cross-coupled beta-beta-dimers are produced. DFRC' treatment of these dimers gave diagnostic products in which acetate groups survived. Several acetylated syringyl beta-beta-linked dimer in DFRC' products of kenaf lignin were detected by GC-MS. The existence of substructures in kenaf lignin which can be derived only from sinapyl acetate coupling or cross-coupling with sinapyl alcohol establishes that acetates on kenaf lignin arise, at least in part, through incorporation of pre-acetylated sinapyl alcohol, as a lignin precursor, via enzyme-mediated radical coupling mechanisms. It is likely that other acylated lignins are formed analogously.