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.

Background: Non-alcoholic fatty liver disease (NAFLD) is triggered by gut-liver axis disorders; enzyme-ultrasound assisted extraction (EAUE) better retains bioactive mulberry polysaccharides (MP) than hot water extraction. This work optimized EAUE by RSM and GA-BP to compare the gut-hepatic protective capacity of two MP preparations and reveal their microecological regulatory mechanism. Methods: We optimized EAUE conditions and characterized the structural features of EAUE-derived MP (MPEU). A 30-day concurrent modeling and MP-administration mouse trial was conducted with biochemical detection and 16S rRNA sequencing to assess MPEU and hot water extraction MP (MPHW) in vivo activity. Results: RSM yielded predictions closer to experimental values, and its optimal extraction conditions were determined as extraction time 107 min, liquid-to-solid ratio 33:1, enzyme addition amount 350 mg, and extraction temperature 52 °C, yielding MP at 10.06 ± 0.03%. MPEU retained complete glycosidic structures and outperformed MPHW in mitigating hepatic steatosis, intestinal damage and inflammation, by restoring SCFA-producing commensal bacteria and suppressing pro-inflammatory flora. Conclusion: In this study, RSM is preferable for EAUE optimization. Structurally intact MPEU exerts stronger NAFLD relief via remodeling gut microecology, promising as nutritional functional food ingredients.