Improving Effect of a Combined Extract of Rhei Rhizoma and Glycyrrhizae Rhizoma through Anti-oxidative Stress in Reflux Esophagitis rats

Abstract

Objectives : The present study was designed to evaluate the anti-inflammatory and anti-oxidative stress activities through regulation of Nrf2-mediated genes by Rhei rhizoma and Glycyrrhiza rhizoma combined extract (RGE) in reflux esophagitis.Methods : The antioxidant activity of RGE in vitro was measured in terms of radical scavenging capacity such as DPPH and ABTS. RGE was administered at 350 mg/kg body weight prior to induction of reflux esophagitis. Reflux esophagitis was induced that tied the pylorus and the transitional junction between the forestomach and the corpus in Sprague-Dawley rats.Results : RGE scavenged DPPH and ABTS effectively and IC₅₀of RGE each were 4.9 μg/ml and 45.6 μg/ml. Our results show that RGE administration markedly ameliorated mucosal damage upon histological evaluation. In serum and esophagus tissue, RGE significantly suppressed the oxidative stress biomarkers. Reflux esophagitis induced rats exhibited down-regulation of antioxidant-related proteins in the esophagus; however, the levels with treatment of RGE were significantly higher than those of vehicle reflux esophagitis rats. RGE treatment caused significant reductions in activation of NF-κB transcription factor. Thus, RGE significantly exhibited potent anti-inflammatory activities by suppressing the protein expression levels of pro-inflammatory proteins such as COX-2 and iNOS and inflammatory cytokines such as TNF-αin the esophagus tissue.Conclusions : Reflux esophagitis caused considerable levels of oxidative stress in the esophageal mucosa and the administration of RGE reduced the esophageal mucosa damage through the regulation of Nrf2 and NF-κB pathways. Our findings can considered as supplementary therapy in the prevention or treatment of reflux esophagitis.