Ultrasound-assisted enzyme extraction of Dendrobium Officinale polysaccharides: Extraction process, characterization, immunomodulatory effects

Dendrobium Officinale is a traditional Chinese medicinal and edible herb, and polysaccharides being its principal active components. We employed ultrasonic-assisted enzymatic extraction to obtain polysaccharides from Dendrobium Officinale (DOP) and optimized the extraction process using the GA-BP method. Subsequently, DOP was characterized using HPLC, SEM, and HPGPC. Finally, an immunocompromised mouse model induced by cyclophosphamide was adopted to evaluate the immunomodulatory effects. The results showed that the optimal extraction process of ultrasound-assisted enzyme method was 102 min ultrasonic extraction time, 48 °C extraction temperature, 1:80 material-liquid ratio, and 1600 U/g enzyme additions. The predicted polysaccharide yield was 29.64 %, and the actual polysaccharide yield was 29.71 ± 0.31 %. DOP is a white powder with pore-like structure, whose polysaccharide content is 90.66 ± 2.47 %, and with a composition of D-mannose, glucose, galactose, arabinose in a molar ratio of 74.17: 47.80: 9.03: 1. DOP has demonstrated the ability to improve the general condition of mice with cyclophosphamide-induced immunosuppression. It mitigates damage to the thymus and spleen tissues, increases white blood cell counts, regulates the ratio of T lymphocytes and the levels of related factors, enhances macrophage phagocytic function to improve nonspecific immune responses, and boosts the levels of immunoglobulins IgA and IgG to enhance specific immune function. Therefore, DOP can alleviate immunosuppression induced by cyclophosphamide.