Portulaca oleracea extracts and their active compounds ameliorate inflammatory bowel diseases in vitro and in vivo by modulating TNF-α, IL-6 and IL-1β signalling

Abstract

Portulaca oleracea L. (P. oleracea) is an herb that is widely used in traditional medicine to treat various diseases. However, its effects on inflammatory diseases, such as inflammatory bowel disease (IBD), are not yet well characterized. Here, we investigated the impact of the ethyl acetate (EtOAc) and ethanol (EtOH) extracts of P. oleracea on lipopolysaccharide (LPS)-induced inflammatory responses and phosphorylation of ERK, JNK, and p38 expression in RAW264.7 macrophages. In addition, the inhibitory effects of these extracts and fractions on 3% dextran sulphate sodium (DSS)-induced ulcerative colitis were examined using an ICR mouse model. DSS-induced colitis, including body weight loss, reduced colon length, and histological colon injury, was significantly ameliorated in mice fed the P. oleracea extracts (200 and 500 mg/kg). In particular, P. oleracea extracts also inhibited pro-inflammatory cytokine (TNF-α IL-6, and 1L-1β) production in mice with DSS-induced colitis; the P. oleracea extracts displayed higher and/or similar inhibitory activity to sulfasalazine at high concentrations. Furthermore, the chemical structures of active compounds separated from the EtOAc extract of P. oleracea were elucidated using nuclear magnetic resonance (NMR) spectroscopy (see Figure in supplementary materials), resulting in the identification of three known compounds. Among these active compounds, cis-N-feruloyl-3′-methoxytyramine (2) exhibited the strongest effects on preventing DSS-induced IBD in animal models. Thus, extract of P. oleracea and their active compounds represents a new therapeutic approach for patients with inflammatory bowel diseases