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Softwood lignin is a complex, three-dimensional, cross-linked aromatic polymer that constitutes a principal structural component of the secondary cell walls in gymnosperm (coniferous) trees. It is biosynthesized through the oxidative radical coupling of a single monolignol precursor, coniferyl alcohol (4-hydroxy-3-methoxycinnamyl alcohol), which yields guaiacyl (G) units characterized by a single methoxy group on the aromatic ring ^[1]. Unlike the lignin of angiosperm (hardwood) species, which contains both guaiacyl and syringyl (S) units derived from sinapyl alcohol, softwood lignin is composed almost exclusively of guaiacyl units, with only trace amounts of p-hydroxyphenyl (H) units occasionally detected ^[1]. The macromolecular architecture of softwood lignin is defined by a variety of interunit linkages, among which the β-O-4′ aryl ether bond is the most abundant, accounting for approximately 50–60% of all linkages, followed by β-5′ (phenylcoumaran), β-β′ (resinol), and 5-5′ (diphenyl) linkages . These covalent bonds connect the phenylpropanoid units into a highly heterogeneous and branched polymer network that is covalently linked to hemicellulose and cellulose through lignin-carbohydrate complexes, thereby contributing to the mechanical rigidity and hydrophobicity of the wood cell wall ^[2]. The absence of syringyl units and the predominance of guaiacyl moieties impart softwood lignin with distinct physicochemical properties, including a higher degree of structural condensation and a greater proportion of carbon-carbon bonds relative to the ether linkages found in hardwood lignin ^[3].