 8-5' Non cyclic diferulic acid has been identified to be covalently linked to carbohydrate moieties of the arabinogalactan-protein fraction of gum arabic.Diferulic acids are thought to have a structural function in plant cell walls, where they form cross-links between polysaccharide chains.They have been extracted attached to a few sugar molecules at both ends, but so far no definitive proof of them linking separate polysaccharide chains has been found.