Structure identification and in vitro immunomodulatory activities of polysaccharide AHL26-P from Arachis hypogaea (Tianfu 26) leaves

Peanut leaves, an underutilized agricultural by-product of peanut cultivation, represent a sustainable source of bioactive polysaccharides. In this study, a novel polysaccharide (AHL26-P) was obtained from peanut leaves of Tianfu 26. The chemical structure and biological activities of AHL26-P was elucidated, with emphasis on its immunomodulatory and anti-tumor effects. The results showed that AHL26-P had a heavy average molecular weight (Mw) of 8476 Da. The backbone of AHL26-P consisted of (1 → 4)-Glcp, (1 → 3,6)-Glcp, (1 → 4,6)-Glcp, (1 → 2,6)-Galp, (1 → 6)-β-D-Galp, and four branched chains were terminated by two →2)-α-D-Glcp and two →1)-α-D-Xylp, respectively. Immunoreactivity studies revealed that the proliferation rates of B, T, and RAW 264.7 cells treated with 10 μg/mL of AHL26-P were 79.72 %, 49.36 %, and 86.00 %, respectively. The results of anti-tumor assay revealed that AHL26-P could directly inhibit the proliferation of Mouse Forestomach Carcinoma cell (MFC) and ascites tumor (S180). These results enriched the theoretical research system of peanut leaf polysaccharide and provided a foundation for developing functional foods with immune-enhancing properties.