Physicochemical characterization and protective effects of raw and nine-steamed Polygonatum cyrtonema polysaccharides on cyclophosphamide-induced immunosuppression in mice

Polygonatum cyrtonema (PC) is a traditional Chinese herb used in both food and medicine with considerable bioactivity. The nine-steam processed pieces of PC are the main form of clinical application, while research has focused on the polysaccharide of their crude form. This study evaluated the physicochemical characteristics and protective effects of polysaccharides from both crude PC (PCP) and nine-steamed PC (NPCP) against cyclophosphamide (CTX)-induced immunosuppression. The findings indicate significant differences in the physicochemical characteristics of PCP and NPCP. The nine steaming treatments reduced the polysaccharide content by 8.15 %, and significantly altered monosaccharide proportion. Both polysaccharides accelerated the recovery of spleen and thymus indexes and restored the levels of TNF-α, IL-1β, IL-6, IgA, IgM, and IgG in the serum of CTX-treated mice in a dose-dependent manner as well as improved the morphology of spleen, thymus, and colon tissues. Furthermore, PCP and NPCP promoted the production of SCFAs and the recovery of intestinal flora in CTX-induced immunosuppressed mice. NPCP exhibited a better protective effect against CTX-induced immunosuppression. The results of this study confirm the importance of the nine-steaming method for PC and provide a basis for the further development of NPCP as a functional food to alleviate CTX-induced immunosuppression.