title: Isolation and structural characterisation of 8-O-4/8-O-4- and 8-8/8-O-4-coupled dehydrotriferulic acids from maize bran.
abstract: Two new dehydrotriferulic acids were isolated from saponified maize bran insoluble fiber using Sephadex LH-20 chromatography followed by semi-preparative RP-HPLC. Based on UV-spectroscopy, mass spectroscopy and one- and two-dimensional NMR experiments, the structures were identified as 8-O-4,8-O-4-dehydrotriferulic acid and 8-8(cyclic),8-O-4-dehydrotriferulic acid. Which of the possible phenols in the initially formed 8-8-dehydrodiferulate was etherified by 4-O-8-coupling with ferulate has been unambiguously elucidated. The ferulate dehydrotrimers which give rise to these dehydrotriferulic acids following saponification are presumed, like the dehydrodiferulates, to cross-link polysaccharides. Neither dehydrotriferulic acid described here involves a 5-5-dehydrodiferulic acid unit; only the 5-5-dehydrodimer may be formed intramolecularly. However, whether dehydrotriferulates are capable of cross-linking more than two polysaccharide chains remains open. Although the levels of the isolated ferulate dehydrotrimers are lower than those of the ferulate dehydrodimers, the isolation now of three different dehydrotriferulates indicates that trimers contribute to a strong network cross-linking plant cell wall polysaccharides.
authors.affiliation: Department of Food Chemistry, Institute of Biochemistry and Food Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany.
authors.forename: Carola
authors.initials: C
authors.lastname: Funk
authors.forename: John
authors.initials: J
authors.lastname: Ralph
authors.forename: Hans
authors.initials: H
authors.lastname: Steinhart
authors.forename: Mirko
authors.initials: M
authors.lastname: Bunzel
mesh_terms: D002473:Cell Wall / Q000737:chemistry; D002850:Chromatography, Gel; D003373:Coumaric Acids / Q000737:chemistry* / Q000302:isolation & purification*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry; D003313:Zea mays / Q000033:anatomy & histology / Q000737:chemistry* / Q000166:cytology*
chemical_list: D003373:Coumaric Acids; D011134:Polysaccharides; C004999:ferulic acid; D010100:Oxygen