PHENOLIC COMPOUNDS AS CROSS-LINKS OF PLANT DERIVED POLYSACCHARIDES

Authors: BUNZEL, MIRKO - U OF HAMBURG; Ralph, John; STEINHART, HAN - U OF HAMBURG

Submitted to: Czech Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2004
Publication Date: 10/10/2004
Citation: Bunzel, M., Ralph, J., Steinhart, H. 2004. Phenolic compounds as cross-links of plant derived polysaccharides. Czech Journal of Food Science. 22:39-42.

Interpretive Summary: Connections between and among components (wall cross-linking) that make up plant cell walls strengthens the total cell wall, but negatively impacts economically important natural processes such as the digestion of plants by livestock. Grasses contain small molecules called hydroxycinnamates attached to their cell walls. Hydroxycinnamates are also found in cereal grains, where they may be responsible for some of the health benefits of human dietary fiber. Oxidation reactions of hydroxycinnamates are crucial to a diverse array of important cell wall cross-linking mechanisms. New cross-linking mechanisms continue to be found and are reported here. More extensive cross-linking action by the most important hydroxycinnamate, ferulate, has just been revealed with the discovery of trimeric compounds in which three ferulates, attached to their polysaccharides, are cross-linked. Significant issues remain for separating and quantifying these important components and in understanding their roles in plant function. In additon, a clear understanding of the chemistry and biochemistry of these complex interactions will provide insight into their impact upon other systems such as human and animal nutriton.

Technical Abstract: Plant cell wall polysaccharides are partially cross-linked via phenolic compounds. As shown in the past, the most important phenolic compounds to cross-link plant cell wall polysaccharides are ester-linked ferulic acid dimers, but p-coumarate dimes were also shown to be potential cross-linking compounds. Recently, ferulic acid dimers were identified and quantified in a range of cereal grains. The isolation of 8-O-4-dehydrodiferulic acid diarabinoside from maize bran shows that diferulic acids are able to form intermolecular cross-links between arabinoxylans. The more recently identified sinapic acid dehydrodimers and ferulic acid dehydrotrimers provide additional contributions to building up a strong network of plant cell wall polysaccharides.