Study on Dendrobium officinale O-acetyl-glucomannan (Dendronan): Part IV. Immunomodulatory activity in vivo

• Cultured Dendrobium officinale exhibited immunomodulatory activities reported for the wild varieties.
• The purified polysaccharide fraction is confirmed as one of the main bioactive component of Dendrobium officinale.
• β-(1→4)-Man linkage and O-acetyl structure might be the feature structures responsible for immunomodulatory activity.

As part of a series of studies on the bioactivities and structures of polysaccharides from Dendrobium officinale, this study investigates the immunomodulatory activities of Dendrobium officinale and its two polysaccharide fractions (crude and purified, respectively) in cyclophosphamide induced mice. All three materials protected the body from immunosuppression in a dose-dependent manner. Biological activities related to immunomodulations investigated included stimulating the proliferation of splenocytes, balancing the ratio of spleen lymphocyte subsets and the secretion of serum cytokines, up-regulating the serum IgM, IgG and haemolysin formation, and accelerating the phagocytotic function of peritoneal macrophage. The degree of modulations were higher in purified Dendrobium officinale polysaccharide than crude polysaccharide, indicating that the purified polysaccharide was one of the key bioactive components in Dendrobium officinale, the main structure of which has been identified as O-acetyl-glucomannan (Dendronan)