Effect of daphnetin, the coumarin derivative isolated from Daphne genus, on Helicobacter pylori adhesion to gastric epithelial cells.

Background: Adherence of Helicobacter pylori to the surface of the gastric mucosa is the initial and crucial step for its survival and colonization in the harsh conditions of the stomach. We had previously demonstrated that daphnetin has anti-adhesion effect.

Purpose: This study aims to explore the mechanisms of daphnetin to reduce H. pylori adhesion to gastric epithelial cells (GES-1).

Methods: Fluorescence microscopy and urease assay were used to observe and validate the anti-adhesion effect of daphnetin. Terminal deoxynucleotidyl transferase dUTP nick end labeling, comet assay and agarose gel-based assay were conducted to evaluate the level of DNA damage. Quantitative real-time polymerase chain reaction, western blotting, electrophoretic mobility shifts assay and enzyme-linked immunosorbent assay were performed to investigate the mechanisms of the anti-adhesion effect of daphnetin.

Results: Our results showed that daphnetin decreased H. pylori adhesion to GES-1 in time- and dose-dependent manners. The mechanisms by which daphnetin inhibits H. pylori adhesion involved the inducing of DNA double-strand breaks, the up-regulating of recA transcription leading to RecA binding at 1018-1597 site in the babA promoter, the decreasing of babA/babB transcription ratio, the decreasing of BabA expression and its interaction with Lewis b antigen.

Conclusion: Our results suggested that daphnetin significantly inhibits H. pylori adhesion to GES-1 through the RecA-BabA pathway. To our knowledge, this is the first report on the mechanisms of daphnetin affecting H. pylori adhesion to GES-1.