Ferulates and lignin structural composition in cork

Abstract The structure of lignin and suberin, and ferulic acid (FA) content in cork from Quercus suber L. were studied. Extractive-free cork (Cork), suberin, desuberized cork (Corksap), and milled-cork lignins (MCL) from Cork and Corksap were isolated. Suberin composition was determined by GC-MS/FID, whereas the polymers structure in Cork, Corksap, and MCL was studied by Py-TMAH and 2D-HSQC-NMR. Suberin contained 94.4% of aliphatics and 3.2% of phenolics, with 90% of ω-hydroxyacids and α,ω-diacids. FA represented 2.7% of the suberin monomers, overwhelmingly esterified to the cork matrix. Py-TMAH revealed significant FA amounts in all samples, with about 3% and 6% in cork and cork lignins, respectively. Py-TMAH and 2D-HSQC-NMR demonstrated that cork lignin is a G-lignin (>96% G units), with a structure dominated by β–O–4′ alkyl-aryl ether linkages (80% and 77% of all linkages in MCL and MCLsap, respectively), followed by phenylcoumarans (18% and 20% in MCL and MCLsap, respectively), and smaller amounts of resinols (ca. 2%) and dibenzodioxocins (1%). HSQC also revealed that cork lignin is heavily acylated (ca. 50%) exclusively at the side-chain γ-position. Ferulates possibly have an important function in the chemical assembly of cork cell walls with a cross-linking role between suberin, lignin and carbohydrates.

Download Full-text

A Cork Cell Wall Approach To Swelling And Boiling

10.21203/rs.3.rs-1111682/v1 ◽

2021 ◽

Author(s):

Ana Patrícia Poeiras ◽

Cordula Voguel ◽

Björn Günther ◽

Constança Camilo-Alves ◽

Peter Surový ◽

...

Keyword(s):

Cell Wall ◽

Water Availability ◽

Cell Walls ◽

Quercus Suber ◽

Cork Oak ◽

Cork Stopper ◽

Natural Conditions ◽

Cork Cell ◽

Insight Into ◽

Cell Wall Expansion

Abstract The bark of cork oak (Quercus suber L.) is mostly used for cork stopper production, whereas bark is undergoing a series of industrial procedures, boiling usually leading to changes in the characteristics of the tissue. Trees are traditionally grown under natural conditions; however, irrigation is now being used in plantations. These permanent water availability affects cork-oak development, while its effects on industrial procedures is unknown. This study provides a first insight into the behaviour of the cell walls of cork during the process of swelling and boiling when trees have been grown under irrigation, subject to a specific water regime. Cork tissue was analysed using environmental and scanning electron microscopy under three regimes: raw conditions; following immersion in water; and after boiling. Additionally, the radial expansion of samples was determined. The results showed greater cell-wall expansion in cork from the irrigated site than cork from the traditional rainfed plot, when hydrated for 24h. After boiling, the cell walls of the rainfed site were thinner than in the raw stage, in contrast to the irrigated cork. This study suggests that irrigation during cork-oak growth produces a higher capacity for adsorption, increasing cell-wall thickness from the raw stage to the boiling stage.

Download Full-text

Glycerol-ω-hydroxyacid-ferulic acid oligomers in cork suberin structure

Holzforschung ◽

10.1515/hf.2006.028 ◽

2006 ◽

Vol 60 (2) ◽

pp. 171-177 ◽

Cited By ~ 19

Author(s):

Sara Santos ◽

José Graça

Keyword(s):

Ferulic Acid ◽

Cell Walls ◽

Cross Linking ◽

Macromolecular Structure ◽

Acid Moiety ◽

Model Compounds ◽

Esi Ms ◽

Important Constituent

Abstract Cork suberin was partially depolymerised by methanolysis catalysed by Ca(OH)2. The solubilised depolymerisate was analysed by ESI-MS/MS. The compounds identified included monomers and “dimeric” and “trimeric” oligomers. Among the latter, an oligomer of glycerol esterified to a ω-hydroxyacid esterified to ferulic acid was identified. The “dimeric” structures of glycerol esterified to a ω-hydroxyacid and of a ω-hydroxyacid esterified to ferulic acid were also found in the partially depolymerised fraction. The identification of these molecules was confirmed by synthesis of model compounds and comparison of their ESI-MS/MS spectra. The glycerol-ω-hydroxyacid-ferulic acid trimeric oligomer could be an important constituent block in the suberin structure. Its function is probably to link the two main polymers present in suberised cell walls, namely, polyaliphatic polyesters and lignin-related polyaromatics. The glycerol-ω-hydroxyacid moiety is part of the polyaliphatic polyester and the ferulic acid moiety is esterified to the polyaromatics. These oligomers provide a new insight to understanding of the macromolecular structure of suberin, since they could allow cross-linking of the two structurally different biopolymers.

Download Full-text

Caffeic acid: O-methyltransferases and the biosynthesis of ferulic acid in primary cell walls of wheat seedlings

Phytochemistry ◽

10.1016/0031-9422(95)00810-1 ◽

1996 ◽

Vol 41 (6) ◽

pp. 1507-1510 ◽

Cited By ~ 21

Author(s):

Thi Bach Tuyet Lam ◽

Kenji Iiyama ◽

Bruce A. Stone

Keyword(s):

Ferulic Acid ◽

Caffeic Acid ◽

Cell Walls ◽

Primary Cell ◽

Wheat Seedlings

Download Full-text

Binding Site of the Bridged Macrolides in the Escherichia coli Ribosome

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.1.281-288.2005 ◽

2005 ◽

Vol 49 (1) ◽

pp. 281-288 ◽

Cited By ~ 45

Author(s):

Liqun Xiong ◽

Yakov Korkhin ◽

Alexander S. Mankin

Keyword(s):

Escherichia Coli ◽

Tight Binding ◽

Dimethyl Sulfate ◽

23S Rrna ◽

Side Chain ◽

Macrolide Antibiotics ◽

Side Chains ◽

Alkyl Aryl ◽

E Coli ◽

Exit Tunnel

ABSTRACT Ketolides represent the latest group of macrolide antibiotics. Tight binding of ketolides to the ribosome appears to correlate with the presence of an extended alkyl-aryl side chain. Recently developed 6,11-bridged bicyclic ketolides extend the spectrum of platforms used to generate new potent macrolides with extended alkyl-aryl side chains. The purpose of the present study was to characterize the site of binding and the action of bridged macrolides in the ribosomes of Escherichia coli. All the bridged macrolides investigated efficiently protected A2058 and A2059 in domain V of 23S rRNA from modification by dimethyl sulfate and U2609 from modification by carbodiimide. In addition, bridged macrolides that carry extended alkyl-aryl side chains protruding from the 6,11 bridge protected A752 in helix 35 of domain II of 23S rRNA from modification by dimethyl sulfate. Bridged macrolides efficiently displaced erythromycin from the ribosome in a competition binding assay. The A2058G mutation in 23S rRNA conferred resistance to the bridged macrolides. The U2609C mutation, which renders E. coli resistant to the previously studied ketolides telithromycin and cethromycin, barely affected cell susceptibility to the bridged macrolides used in this study. The results of the biochemical and genetic studies indicate that in the E. coli ribosome, bridged macrolides bind in the nascent peptide exit tunnel at the site previously described for other macrolide antibiotics. The presence of the side chain promotes the formation of specific interactions with the helix 35 of 23S rRNA.

Download Full-text