Structural elucidation of a pectin from roots of Polygala tenuifolia and its neuritogenesis inducing activity in PC12 cells

Pectin is a family of heteropolysaccharides and highly valued for its various bioactivities. Here, a pectin, RP01-1, was purified from roots of Polygala tenuifolia with the molecular weight of 79.1 kDa. Its structure was characterized as alternate 1, 2, 4-linked α-Rhap and 1, 4-linked α-GalpA constituted the backbone, with branches of terminal (T) -, 1, 4- and 1, 3, 6-linked β-Galp, T-, 1, 5- and 1, 3, 5-linked α-Araf substituted at C-4 of 1, 2, 4-linked α-Rhap. The fluorescence spectroscopic analysis indicated that RP01-1 induced neurite outgrowth in PC12 cells and primary cortex neurons in dose dependent manner with no significant cytotoxicity. To disclose the mechanism of this phenomenon, we found that RP01-1 might induce neuritogenesis in PC12 cells via increasing BDNF expression, and promoting the phosphorylation of AKT, ERK, CREB. The results suggest that AKT, ERK, CREB related signaling pathways might implicate in neuritogenesis-inducing activity of RP01-1.