Structure characterization and immunomodulating effects of polysaccharides isolated from Dendrobium officinale

Abstract

A crude polysaccharide fraction (cDOP) has been determined to be the characteristic marker of Dendrobium officinale, an expensive tea material in Asia, but its chemistry and bioactivity have not been studied. In work reported here, cDOP was de-starched (DOP, 90% yield), and separated into two polysaccharides, DOP-1 and DOP-2, which were characterized by monosaccharide composition and methylation analyses, and spectral analyses (FT-IR and 1 H and 13 C NMR). Both are composed of mannose and glucose, at similar ratios; and have a similar structure with a backbone of 1,4-linked β-D-mannopyranosyl and β-D-glucopyranosyl residues. Significant differences were observed only in their molecular weights. Bioassay using mouse macrophage cell line RAW 264.7 indicated that DOP and its two sub-fractions enhance cell proliferation, TNF-α secretion, and phagocytosis in a dose-dependent manner. They also induced the proliferation of lymphocytes alone and with mitogens. DOP-1 and DOP-2 are thus proven to be major, active polysaccharide markers of D. officinale.

Character and laxative activity of polysaccharides isolated from Dendrobium officinale

“…HPLC and LC-MS analyses indicated that DOP was mainly composed of D-glucose (830.98 mg/g) and D-mannose (59.19 mg/kg), in accordance with a previous study (Wei et al, 2016). As an essential glyconutrient for human health, mannose is a popular nutritional and health-beneficial food supplement (Hu et al, 2016).…”

“…D. officinale has been widely used in porridge, soup and dishes as a highquality health food in diets and was approved by the China Food and Drug Administration (CFDA) (Meng et al, 2013;Wei et al, 2016). Phytochemical analyses showed that D. officinale was mainly composed of polysaccharides, with some low molecular weight compounds such as bibenzyls, phenanthrenes and flavanones (Chen et al, 2012).…”

Structural characterisation and immunomodulatory effects of polysaccharides isolated from Dendrobium aphyllum

“…4a, most of the absorption bands could be assigned in accordance with the previous literature (Xing et al, 2015;Wei et al, 2016). 4a, most of the absorption bands could be assigned in accordance with the previous literature (Xing et al, 2015;Wei et al, 2016).…”

“…The phenol-sulphuric acid assay, with glucose as a standard, was used to determine the total sugar content, and the modified carbazole and sulphuric acid method, with D-glucuronic acid as the standard, was used to determine the uronic acid content (Masuko et al, 2005;Westwood et al, 2011). The O-acetyl content was determined by phenolphthalein endpoint titration (Wei et al, 2016). The O-acetyl content was determined by phenolphthalein endpoint titration (Wei et al, 2016).…”

“…Total starch was beyond detection, and protein content was low in cDAP and DAP a , indicating highly pure fractions isolated. The O-acetyl group in DAP may affect acetylation activity through the action of specific enzymes or proteins in vivo (Wei et al, 2016). The O-acetyl group in DAP may affect acetylation activity through the action of specific enzymes or proteins in vivo (Wei et al, 2016).…”