Molecular characteristics and antioxidant activity of bamboo node and internode lignin–carbohydrate complexes

Bamboo nodes and internodes exhibit markedly distinct structural and functional characteristics, and variations in their lignin–carbohydrate complexes (LCCs) directly affect bamboo processing and utilization. In this study, the structural features and antioxidant activities of LCCs extracted from bamboo nodes and internodes were systematically compared. The results demonstrated that node LCCs possessed higher molecular weights (2853–3529 g·mol −1 ), pronounced enrichment of syringyl (S) units, higher levels of p -coumarate ( p CA) modification, and more abundant phenyl glycoside linkages, resulting in highly condensed and thermally stable lignin–polysaccharide networks. In contrast, internode LCCs contained higher proportions of guaiacyl (G) units and ferulate (FA) linkages, exhibited more uniform structural features, and were more susceptible to thermal decomposition. Antioxidant assays further revealed that LCC-Ac displayed IC 50 values of 0.57–0.58 mg·mL −1 against DPPH radicals and 3.88–5.74 μg·mL −1 against ABTS radicals, which were significantly lower than those of the other LCC fractions. Overall, this study elucidates the structure–function relationships of LCCs from bamboo nodes and internodes, providing a theoretical basis for understanding bamboo cell wall recalcitrance and for the development of bamboo-based functional materials.