Lopes M H, Gil A M, Silvestre A J, Neto C P
Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
J Agric Food Chem. 2000 Feb;48(2):383-91. doi: 10.1021/jf9909398.
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.
通过对栓皮栎软木进行逐步碱性甲醇解得到的木栓质提取物的单体组成，采用气相色谱-质谱联用（GC-MS）进行了测定。结果表明，在温和碱性条件下，1-链烷醇、链烷酸和α,ω-链烷二酸优先被去除，而在更强碱性条件下，中链修饰的ω-羟基链烷酸优先被去除。发现饱和ω-羟基链烷酸在所有木栓质提取物中含量丰富。这些结果与木栓质细胞壁中位置不同和/或酯化程度不同的两个不同木栓质组分一致。有人提出，这些组分与软木和木栓质提取物的固态（13）C NMR光谱中的两个主要木栓质峰相关。定量GC-MS分析表明，木栓质单体约占木栓质提取物的30%（w/w），其余部分为通过蒸气压渗透法测定的具有高M(n)值的非挥发性结构。相应的NMR光谱证实了木栓质提取物中存在大部分高分子量脂肪族结构。
