Institute of Drug Discovery Technology, Ningbo University, Ningbo, Zhejiang 315211, China.
J Agric Food Chem. 2024 Aug 14;72(32):18056-18066. doi: 10.1021/acs.jafc.4c03469. Epub 2024 Aug 1.
A major factor limiting bark's industrial use is its greater recalcitrance compared to wood. While lignin is widely recognized as a significant contributor, precise characterization of lignin in bark remains sparse, presenting a crucial gap that impedes understanding of its impact. In this study, we employed advanced solid-state nuclear magnetic resonance (NMR) spectroscopy to analyze bark samples from various species, including willow, poplar, and pine. We established and verified that lignin methoxy peak at 56 ppm serves as a reliable quantitative metric to assess lignin content, with which we calculated the lignin contents in bark are significantly reduced by more than 70% compared to those in wood. Furthermore, characterization revealed significant reduction of β-ether linkage in bark lignin across species, revealing a more condensed and resistant structural configuration. Our results have substantially advanced our comprehension of the composition and structure of native lignin in tree bark.
限制树皮工业应用的一个主要因素是其与木材相比的较高的抗降解性。虽然木质素被广泛认为是一个重要的贡献者，但树皮中木质素的精确表征仍然很少，这是一个关键的差距，阻碍了对其影响的理解。在这项研究中，我们采用了先进的固态核磁共振（NMR）光谱技术来分析来自不同物种的树皮样本，包括柳树、杨树和松树。我们建立并验证了木质素甲氧基峰在 56 ppm 处可作为评估木质素含量的可靠定量指标，据此我们计算出树皮中的木质素含量比木材中的木质素含量降低了 70%以上。此外，表征结果表明，树皮木质素中的β-醚键显著减少，揭示了更紧凑和更具抗性的结构构象。我们的研究结果大大提高了我们对树木树皮中原生木质素的组成和结构的理解。
