Crude Polysaccharide Extracts from Fresh and Dried Cistanche deserticola Attenuate Cyclophosphamide-Induced Immunosuppression in Mice

Primary drying is a routine operation for Cistanche deserticola, a traditional tonic whose polysaccharides serve as functional ingredients, yet whether it reshapes their fine structure and alters their biological effects remains unclear. Two crude polysaccharide extracts from fresh (FCDPE) and dried (DCDPE) C. deserticola were preliminarily characterised via gel-permeation chromatography, gas chromatography–mass spectrometry and infrared spectroscopy. Both extracts were predominantly composed of carbohydrates (total carbohydrate contents of 80.82% and 82.24%, respectively) and showed comparable main-peak apparent molecular weights; FCDPE retained a markedly higher arabinose proportion, whereas DCDPE was glucose-dominated and showed systematically smaller minor high-molecular-weight fractions. In cyclophosphamide-immunosuppressed mice, both preparations were associated with partially restored proportions of circulating CD3+ and CD19+ cells and with attenuated splenic and colonic injury relative to the model group. Microbiota profiling and faecal metabolomics revealed preparation-specific signatures: Lachnospiraceae were enriched in the FCDPE group, and Peptococcaceae were enriched in the DCDPE group, in contrast to the Enterobacteriaceae enrichment of the model group. Amino acids, oligopeptides and acylcarnitines were elevated in the FCDPE group, ceramides and succinate were decreased in both groups, together with the five lysophospholipid features shared by the two comparisons; and steroid biosynthesis was the most enriched pathway in both comparisons, although after Benjamini–Hochberg correction, it remained significant only in the DCDPE comparison (adjusted p = 0.029; adjusted p = 0.44 in the FCDPE comparison). Primary drying of C. deserticola therefore alters the composition of these crude extracts, and these compositional changes are accompanied by distinct microbial and metabolic signatures and by convergent, though partial, recovery of the measured immune readouts. These microbial and metabolic associations are exploratory and hypothesis-generating rather than confirmatory.