Lignin dimeric units are characterized by various inter-unit linkage types such as β-O-4, β-5, β-β, and β-1. Spirodienones are the native form of the β-1 structures, but the content in lignin has not been clarified. In this study, the ring-1-13C labeled coniferin was synthesized and administered to Ginkgo biloba shoots, obtaining ring-1 selectively labeled xylem samples. Enzymatically saccharified lignin (EL) samples were prepared from the xylem sample (400–600 µm distant region from the cambial zone), and solution-state quantitative 13C NMR and solid-state CP/MAS NMR measurements were conducted. Acetylated EL (ELAc) was also prepared from the xylem sample (600–800 µm distant region from the cambial zone), and solution-state quantitative 13C NMR and 1H–13C 2D NMR measurements were conducted. Difference spectra obtained by subtracting the unlabeled spectra from the ring-1 labeled spectra showed that the ring-1 was responsible for broad signals at 134 ppm and signals of the spirodienone structure at 56.11 ppm (in solid-state), 54.70 ppm (EL in solution-state), and 54.72 ppm (ELAc in solution-state). The ratio of spirodienone structure was evaluated as 0.68 % (EL) and 0.72 % (ELAc) by the solution-state quantitative 13C difference spectra, and 2.3 % (ELAc) by HSQC volume ratio of Cα′-H to G2-H.

中文翻译：

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通过给予[ring-1-13C]松柏苷定量分析木质素中的β-1结构

木质素二聚体单元的特征在于各种单元间键合类型，例如β-O-4、β-5、β-β和β-1。螺二烯酮是β-1结构的天然形式，但木质素中的含量尚未明确。在这项研究中，ring-1-13合成 C 标记的松柏苷并施用至银杏叶芽，获得ring-1选择性标记的木质部样本。酶法糖化木质素 (EL) 样品由木质部样品（距形成层区 400–600 µm 远的区域）制备，并进行溶液态定量13进行了 13 C NMR 和固态 CP/MAS NMR 测量。乙酰化 EL (ELAc) 也由木质部样品（距形成层区 600–800 µm 远的区域）制备，并进行溶液态定量1313C核磁共振和1H-13进行了 13C 2D NMR 测量。通过从ring-1标记光谱中减去未标记光谱获得的差异光谱表明，ring-1负责134 ppm处的宽信号和螺二烯酮结构在56.11 ppm（固态）、54.70 ppm（EL中的EL）处的信号。溶液状态）和 54.72 ppm（溶液状态的 ELAc）。通过溶液状态定量测定，螺二烯酮结构的比例为0.68％(EL)和0.72％(ELAc)13C 差谱，以及 HSQC 测得的 Cα'-H 与 G2-H 的体积比为 2.3% (ELAc)。