Punicalagin ameliorates DSS-induced colitis in mice through strengthening gut barrier, decreasing oxidative stress and downregulating inflammation via AMPK–NF–κB-STAT3 pathway

Abstract

Inflammatory bowel disease is characterized by compromised epithelium barrier function and hyperactive intestinal inflammation. This study aims to investigate the effects of punicalagin, a bioactive ellagitannin in pomegranate, on dextran-sodium sulfate (DSS) - induced colitis in mice and to examine the underlying mechanisms involved. Oral administration of punicalagin (100 mg/kg/day) effectively mitigated the severity of experimental colitis in mice, evidenced by increased colon length, improved intestinal permeability, and decreased histological scores. Punicalagin up-regulated the mRNA expression level of Muc2 in and the protein expression of zonula occludens-1 (ZO-1) and Occludin in colitic mice. Moreover, punicalagin effectively decreased reactive oxygen species (ROS) levels in the colon, and in Caco-2 cells exposed to H2O2in vitro. Mechanistically, punicalagin attenuated inflammation by inhibiting the secretion of interleukin-6 (IL-6) and the phosphorylation of the NF-κB/STAT3 pathway. In addition, punicalagin increased adenosine monophosphate activated protein kinase (AMPK) phosphorylation in the colon of DSS-treated mice and lipopolysaccharide (LPS) -induced RAW 264.7 macrophages. Knocking down AMPKα by siRNA diminished punicalagin's anti-inflammatory function in RAW 264.7 macrophages exposed to LPS. Furthermore, molecular docking analysis, cellular thermal shift assay (CETSA), and drug affinity responsive target stability (DARTS) analysis supported the direct interaction between punicalagin and AMPK. In conclusion, punicalagin could mitigate DSS-induced colitis through enhancing intestinal epithelial barrier, alleviating oxidative stress, and attenuating inflammation partly through modulation of AMPK–NF–κB-STAT3 pathway.