Structural characterization and immunomodulatory activity of two novel polysaccharides derived from the stem of Dendrobium officinale Kimura et Migo

Abstract

Two novel polysaccharide fractions, DOPW-1 and DOPW-2, were successfully isolated from the crude polysaccharide of Dendrobium officinale Kimura et Migo and purified using diethylaminoethyl (DEAE)-cellulose 52 and Sephacryl S-300HR column chromatography. Their average molecular weight, monosaccharide composition, and linkage were investigated and a possible structure of the repeat units was inferred. DOPW-1 and DOPW-2 exhibited better immunomodulatory activity than that of the major, water-soluble polysaccharide fraction (DOPW), significantly (P < 0.05) promoting macrophage proliferation and increasing macrophage phagocytosis and nitric oxide production. Fluorescence microscopy of fluorescein isothiocyanate (FITC)-labelled DOPW-1 revealed that polysaccharide may attach to the surface of RAW 264.7 cells or enter the inside of the cells. These findings suggested the potential for exploiting DOPW-1 and DOPW-2 not only as novel potential immunomodulators but also as intuitive tools for research on the molecular mechanisms underlying polysaccharide efficacy.

Keywords

• Dendrobium officinale Kimura et Migo
• Polysaccharide
• Purification
• Structure
• Immunomodulatory activity
• Fluorescence microscopy