Synthesis of novel lignin model compounds labeled with alkynyl and their potential application

In this study, vanillin was applied to yield 2-O-propargyl coniferin, onto which alkynyl groups could be introduced at sites that do not participate in dehydrogenation polymerization (ortho position of the benzene ring), thus avoiding changes in the structure of the lignin side chains and functional groups on the benzene ring. In order to evaluate whether these synthetic monomers can effectively participate in the biosynthesis of lignin, five different dehydrogenation polymers (DHPs) were generated with the help of β-glucosidase, glucose oxidase and peroxidase. The results showed that, compared with DHP synthesized from a monomer without alkynyl labeling, the basic structure of DHP synthesized from 2-O-propargyl coniferin was not changed. Therefore, the alkynyl-labeled lignin monomer 2-O-propargyl coniferin showed good biocompatibility, and it might participate in the biosynthesis of plant lignin while having negligible impact on the structure of lignin. The designed lignin monomer could provide a new idea for the research of the plant lignification process.