Isolation of lignin-carbohydrate bonds in wood

木质素经20倍摩尔臭氧臭氧氧化16h后，木粉中的木质素主要为木质素，约占木质素的96%，降解为极低分子量结构，不能生成酸不溶木质素。另一方面，红松木材经臭氧氧化和酸解后，可以分离出分子中含有苄基醚型LCC键的LCC产物。阴离子交换层析后，酸性组分中含有LCC产物，酸性组分是木质素有机酸和多糖酸性糖等多种产物的混合物。许多产品的保留时间与三甲基硅烷化后的LCC产品在GC图谱上的保留时间相近，LCC产品的鉴定非常困难。但在乙酰化反应后，三甲基硅化反应的效果有所改善。从葡萄糖和甘露糖键合的LCC模型化合物中都分离到了LCC产物，也从红松木中分离到了一些在GC图谱上与这些LCC产物具有相同保留时间的产物。从红松木中分离得到的产物在总离子色谱图上的保留时间与从LCC模型化合物中分离出的LCC产物在总离子色谱图上的保留时间相同，并显示出相似的质量碎片模式。因此，这些结果表明，红松木中木素与己糖(如葡萄糖和甘露糖)之间的苄基醚型LCC键是通过臭氧氧化和酸解分离出来的，没有LCC键的断裂。

Mostly lignin, it is about 96% lignin in wood meal, was degraded to very low molecular weight structures which could not give acid insoluble lignin after ozonation for 16 hours with 20 times molar ozone. On the other hand, LCC products which contain a benzyl ether type LCC bond in a molecular were isolated from red pine wood after ozonation followed by acid hydrolysis. LCC products were included in the Acidic fraction after anion exchange chromatography, the Acidic fraction was mixture of many products such as organic acids from lignin and acidic sugars from polysaccharides. Many products gave similar retention time compare with that of LCC products on GC chromatogram after trimethylsilylation, identification of LCC products was very difficult. However, it was improved after acetylation instead of trimethylsilylation. LCC products were isolated from both glucose and mannose bonded LCC model compounds and some products which give same retention time on GC chromatogram with these LCC products were also isolated from red pine wood. These products isolated from red pine wood gave same retention time on total ion chromatogram and showed similar mass fragment pattern, compared with LCC products isolated from LCC model compounds. Therefore, these results suggested that benzyl ether type LCC bonds between lignin and hexoses, such as glucose and mannose, were isolated from red pine wood by ozonation followed acid hydrolysis without LCC bond cleavage.