Submitted to: Journal of the Chemical Society Chemical Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/2001
Publication Date: N/A
Citation: Interpretive Summary: Lignin is a major component in all plants that limits digestion by animals, and must be removed from fiber to make fine paper. Lignins are normally made from just one or two component "monomers" (or building blocks) but some plants have lignins that appear to be made from compounds derived from these monomers. Kenaf lignin is quite unusual in having a very high amount of acetate groups on its lignin. A question that has not been satisfactorily answered is whether these acetates are attached to the lignin building blocks before lignin is made, or to the lignin polymer itself (after it is made). We used a novel approach to provide evidence strongly suggesting that it is the lignin building blocks that are acetylated. The interest in this process is 3-fold. Firstly, in a basic sense, it will redefine just what constitutes a lignin building block. Secondly, the potential to remove or introduce these groups into plants by altering biochemical pathways may shed light on their role. Thirdly, changing a plant's lignin composition changes the properties of the lignin. Doing so may improve the digestion of plants by ruminant animals or enhance the pulping properties of woody plants for papermaking. Such studies are at the heart of efforts to improve agricultural sustainability.
Technical Abstract: Whether native lignin acylation occurs at the monolignol stage or post-lignification has not been determined. Here we provide preliminary evidence that sinapyl acetate is a monomer in Tainung kenaf bast fiber lignin. Mono- and di-acetylated syringyl aryltetralins were released from kenaf lignins following a degradative method employing no acetyl-containing reagents; only a non-acetylated analog derives from ¿normal¿ lignins. The same products result from degradation of dehydrodimers derived from sinapyl acetate, or sinapyl acetate/sinapyl alcohol cross-products.