Polysaccharides from Dioscorea batatas Induce Tumor Necrosis Factor-α Secretion via Toll-like Receptor 4-Mediated Protein Kinase Signaling Pathways

The bioactive polysaccharides (named ZPF1) from yam (Dioscorea batatas) were chemically determined, suggesting repeating β-1,4-mannan as mainly having a feature of acetylation on C2−OH and C3−OH, around 28%. The ZPF1 participated in the stimulation of murine wild-type macrophages predominantly in tumor necrosis factor-α (TNFα). Toll-like receptor 4 is proved to be one of the cellular receptors in ZPF1-mediated TNFα secretion. Reactive oxygen species transmission and PI3-kinase are found necessary for regulating TNFα secretion by ZPF1 stimulation. Moreover, we found that extracellular signal-regulated kinase 1/2, Jun N-terminal kinase 1/2, and p38 mitogen-activated protein kinase play important roles in the regulation of TNFα secretion in ZPF1-stimulated macrophages.