Polysaccharide CharacterizationImmunomodulatory activity
A B S T R A C TThe crude polysaccharide from the stem of Dendrobium officinale (DOP) was obtained by water extraction and ethanol precipitation. Two fractions of DOP, DOP-1 and DOP-2, were fractioned by DEAE cellulose and Sephacryl S-400 gel filtration column chromatography.Their molecular weights and monosaccharide compositions were studied. The immunomodulatory activity of DOP, DOP-1 and DOP-2 was evaluated with in vitro cell models.The results showed that the 533.7 kDa DOP-1 and 159.5 kDa DOP-2 were mainly composed of mannose and glucose. Both DOP and its purified fractions significantly (P < 0.05) promoted splenocyte proliferation, enhanced natural killer cell-mediated cytotoxicity, and increased the phagocytosis and nitric oxide production of macrophages. Moreover, these two fractions caused a significant (P < 0.05) stimulation of cytokine secretion of both splenocytes and macrophages. These findings suggest that Dendrobium officinale polysaccharides should be explored as novel potential immunomodulators.
The immunoactivity was evaluated of Dendrobium officinale Kimura & Migo, a Chinese herbal plant, and its crude polysaccharides. Different dosages of D. officinale and its polysaccharides were orally administered to healthy BALB/c mice. The control group was given distilled water. After 4 weeks, immune parameters, including cellular immunity (delayed-type hypersensitivity and natural killer cell activity), humoral immunity (serum hemolytic complement activity), nonspecific immunity (peritoneal macrophage phagocytosis) and interferon-γ production by splenocytes were measured. The results showed that D. officinale and its polysaccharides can significantly enhance cellular immunity and nonspecific immunity in mice. Humoral immunity was also enhanced after oral administration of D. officinale, but the polysaccharides had no influence. Both D. officinale and its polysaccharides markedly increased IFN-γ production by murine splenocytes. Six fractions were isolated from the polysaccharides; the molecular weight of the major fraction was 533,700 Da, and composed of mannose, glucose and rhamnose in a molar ratio of 7.3:1.3:1.0.
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