Polysaccharide from Ma-chi-xian (Portulacae oleracea L., POLP) was prepared and the therapeutic effect on dextran sodium sulfate-induced colitis mice was investigated in this study. The results of clinical activity score and H&E staining confirmed the therapeutic effect of POLP. POLP could diminished the symptoms of colitis and improve colon histopathological structure of the colitis mice. The expression levels of four cytokines were determined. The concentrations of PGE2 and IL-6 were downregulated by POLP treatment. The COX-2 protein expression levels and the STAT3 phosphorylation levels were detected. The results showed that these two protein levels were all increased in colitis and decreased after POLP treatment, indicating that these two proteins were closely related with the protective effect of POLP. Because the synthesis of PGE2 is catalyzed by COX-2 and phosphorylation of STAT3 can induce the expression of COX-2, it was concluded that STAT3 was a key protein related to the POLP exerting its activity in colitis.
Keywords: DSS; POLP; STAT3; colitis.