Brassica rapa L. Polysaccharides Alleviate Cyclophosphamide-Induced Intestinal Mucosal Injury in Mice by Modulating Oxidative Stress, Immune Responses, and Gut Microbiota

This study systematically evaluated the modulatory effects of Brassica rapa L. polysaccharides (BRP) on intestinal mucosal injury in a CTX-induced mouse model. The results showed that high-dose BRP (HBRP) significantly alleviated oxidative damage, with CAT activity increased by approximately 2-fold, SOD increased by 1.3-fold, GSH-Px increased by 70%, and MDA levels decreased by 65%. Meanwhile, liver injury was improved, as ALT and AST decreased by 35% and 55%, respectively. CTX markedly suppressed immune function, while BRP intervention significantly restored cytokine levels, with IL-1β increased by up to 2.5-fold, TNF-α by 1.3-fold, and IL-4 by 2.1-fold. In addition, BRP significantly modulated gut microbiota composition. The number of unique ASVs decreased from 316 in the normal control (NC) group to 63 in the model control (MC) group and recovered to 140 in the HBRP group. At the phylum level, Bacillota increased from 55% to 97% (MC) and decreased to 65% after BRP intervention, while Bacteroidota recovered to 25%. At the genus level, Candidatus_Arthromitus decreased from 40% to nearly 0%, whereas beneficial bacteria such as Ligilactobacillus and norank_f__Muribaculaceae were restored. Overall, BRP effectively alleviates CTX-induced intestinal injury in a dose-dependent manner through antioxidant, immunomodulatory, and gut microbiota–regulating mechanisms.