Variability in Lignin Composition and Structure in Cell Walls of Different Parts of Macaúba ( Acrocomia aculeata ) Palm Fruit

• Published in: Journal of agricultural and food chemistry Vol. 66; no. 1; pp. 138 - 153
• Main Authors: Rencoret, Jorge, Kim, Hoon, Evaristo, Anderson B., Gutiérrez, Ana, Ralph, John, del Río, José C.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 10.01.2018
• Subjects: 2D-NMR; acetates; Acrocomia aculeata; acylation; BASIC BIOLOGICAL SCIENCES; cell walls; DFRC; endocarp; epicarp; lignin; moieties; piceatannol; Py-GC/MS; stalk; stilbenes
• ISSN: 0021-8561; 1520-5118; 1520-5118
• DOI: 10.1021/acs.jafc.7b04638

The lignins from different anatomical parts of macaúba (Acrocomia aculeata) palm fruit, namely stalks, epicarp and endocarp, were studied. The lignin from stalks was enriched in S-lignin units (S/G ~1.2) and β-ether linkages (84% of the total), and was partially acylated at the γ-OH of the lignin side-chains (26% lignin acylation), predominantly with p-hydroxybenzoates and acetates. The epicarp lignin was highly enriched in G-lignin units (S/G 0.2) and consequently depleted in β-ethers (65%) and enriched in condensed structures such as phenylcoumarans (24%) and dibenzodioxocins (3%). The endocarp lignin was strikingly different from the rest and presented large amounts of piceatannol units incorporated into the polymer. This resulted in a lignin polymer depleted in β-ethers but enriched in condensed structures and linked piceatannol moieties. The incorporation of piceatannol into the lignin polymer seems to have a role in seed protection.