Arabinose Conjugates Diagnostic of Ferulate-Ferulate and Ferulate-Monolignol Cross-Coupling Are Released by Mild Acidolysis of Grass Cell Walls

Catherine Lapierre (1) , Aline Voxeur (1) , Stéphanie Boutet (1) , John Ralph (2)

1 IJPB - Institut Jean-Pierre Bourgin
2 University of Wisconsin-Madison

Ferulate (FA) units esterified to grass arabinoxylans are involved in cross-linking cell wall polymers. In this work, this contention is strengthened by the identification of FA homo-and heterodimers esterified to methyl arabinofuranoside (MeAra) units after their release from the xylan by mild acidolysis in dioxane/methanol/HCl. Acidolysis of poorly lignified maize bran cell walls provided diferulate (DFA) isomers, including those from 8−5, 8−O−4, and 5−5 interunit bonding, esterified to one or two MeAra units. Acidolysis of lignified grass samples released crossed dimers esterified to one MeAra unit and derived from the β−O−4 coupling of coniferyl alcohol to FA esters. The evaluation of these heterodimeric esters by LC-UV of their aglycones revealed that the parent structures occur in significant amounts in lignified cell walls (0.5−1 mg/g expressed as FA equivalents). The present results position mild acidolysis as an efficient strategy to obtain improved details regarding the FA-mediated cross-linking of grass cell walls.

Keywords: dehydrodimer; lignification; cell wall cross-link; diferulate; monocot; radical coupling

Domains: Life Sciences [q-bio]

Catherine Lapierre, Aline Voxeur, Stéphanie Boutet, John Ralph. Arabinose Conjugates Diagnostic of Ferulate-Ferulate and Ferulate-Monolignol Cross-Coupling Are Released by Mild Acidolysis of Grass Cell Walls. Journal of Agricultural and Food Chemistry, 2019, 67, pp.12962 - 12971. ⟨10.1021/acs.jafc.9b05840⟩. ⟨hal-03080299⟩