Structural characterization and immunomodulating activity of polysaccharide from Dendrobium officinale

A neutral heteropolysaccharide (DOP-1-1) consisted by mannose and glucose (5.9:1) with an average molecular weight at about 1.78 x 10(5) Da was purified from Dendrobium officinale. Based on Fourier transform infrared spectrum (FT-IR) and nuclear magnetic resonance (NMR) spectra, it suggested that partial structure of DOP-1-1 is an O-acetylated glucomannan with beta-D configuration in pyranose sugar forms. The immunomodulatory activity of DOP-1-1 was evaluated by secretion level of cytokine (interleukin (IL)-1 beta and IL-10) and tumor necrosis factor (TNF)-alpha; in vitro. Our results suggested that DOP-1-1 could stimulate cytokine production (TNF-alpha, IL-1 beta) in cells. These findings demonstrated that the purified polysaccharide from D. officinale presented significant immune-modulating activities. Furthermore, by Western-blot we can found that the signaling pathways of DOP-1-1 induced immune activities involving ERK1/2 and NF-kappa B. As to antioxidant activity, DOP-1-1 hadn't showed remarkable scavenging capacity of 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) in contrast with other studies of polysaccharides from D. officinale. (C) 2015 Elsevier B.V. All rights reserved.