title: Composition of suberin extracted upon gradual alkaline methanolysis of Quercus suber L. cork.
abstract: The monomeric composition of suberin extracts obtained by gradual alkaline methanolysis of Quercus suber cork was determined by gas chromatography-mass spectrometry (GC-MS). Results show that 1-alkanols and alkanoic and alpha,omega-alkanedioic acids are preferentially removed upon mild alkaline conditions, whereas mid-chain-modified omega-hydroxyalkanoic acids are preferentially removed under stronger alkaline conditions. Saturated omega-hydroxyalkanoic acids are found to be abundant in all suberin extracts. These results are consistent with two distinct suberin fractions with different locations in cork cell walls and/or esterification degrees. It is proposed that these fractions correlate with the two main suberin peaks in the solid state (13)C NMR spectra of cork and suberin extracts. Quantitative GC-MS analysis showed that suberin monomers comprise approximately 30% (w/w) of the suberin extracts, the remaining comprising nonvolatile structures with high M(n) values, as measured by vapor pressure osmometry. The presence of a large fraction of high molecular weight aliphatic structures in suberin extracts is supported by the corresponding NMR spectra.
authors.affiliation: Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
authors.forename: M H
authors.initials: MH
authors.lastname: Lopes
authors.forename: A M
authors.initials: AM
authors.lastname: Gil
authors.forename: A J
authors.initials: AJ
authors.lastname: Silvestre
authors.forename: C P
authors.initials: CP
authors.lastname: Neto
mesh_terms: D008401:Gas Chromatography-Mass Spectrometry; D006863:Hydrogen-Ion Concentration; D008055:Lipids; D009682:Magnetic Resonance Spectroscopy; D008563:Membrane Lipids / Q000737:chemistry*; D008697:Methane; D014197:Trees / Q000737:chemistry*
chemical_list: D008055:Lipids; D008563:Membrane Lipids; C065875:suberin; D008697:Methane