Gastritis and ulcers are common inflammatory-based diseases mainly caused by Helicobacter pylori. During gastric inflammation, immune cells release different pro-inflammatory mediators including TNFα, which in turn lead to IL-8 release by gastric epithelial cells through the NF-κB pathway. The side effects of the current anti-H. pylori therapy support the search for new therapeutic approaches. Besides the wide use in the food industry, female inflorescences of Humulus lupulus L., (hop strobiles) show anti-inflammatory and anti-H.pylori activities; however, no studies regarding the anti-inflammatory activity at gastric level have been reported so far.
The aim of this study was to evaluate the anti-inflammatory effect of the water (WE) and hydro-alcoholic (HE) extracts from hops in human gastric epithelial cells (AGS).
Extracts were prepared from H. lupulus cv. Cascade (1:10 ratio drug/solvent) and tested on AGS cells challenged with TNFα. Reporter plasmids were used to assess the NF-κB driven transcription and the IL-8 promoter activity, while IL-8 secretion was evaluated by ELISA assay.
Both WE and HE inhibited IL-8 promoter activity (IC50: 3.59 vs. 2.34 μg/mL, respectively) and the effect was confirmed on NF-κB driven transcription (IC50: 2.25 vs. 2.44 μg/mL, respectively), but only HE inhibited IL-8 release (IC50: 3.95 μg/mL).
The in vitro gastric digestion of HE slightly reduced IL-8 secretion (IC50: 6.40 μg/mL). HE was separated on a MPLC silica column eluted with a stepwise gradient of n-hexane to EtOAc, and then to MeOH; 11 fractions (A-M) were collected. The most active fraction (D) was further purified on a HPLC Gemini 10 µm column eluted with H2O-MeOH (2:8) to obtain pure xanthohumol, which showed anti-inflammatory activity as well.
The present research firstly demonstrates the anti-inflammatory activity of hops at gastric level; if confirmed by future studies, hops extracts may be used to treat or prevent gastric inflammatory diseases.