Inhibitory effect of piperine on Helicobacter pylori growth and adhesion to gastric adenocarcinoma cells.

Background: Piperine is a compound comprising 5-9% of black pepper (Piper nigrum), which has a variety of biological roles related to anticancer activities. Helicobacter pylori has been classified as a gastric carcinogen, because it causes gastritis and gastric cancer by injecting the virulent toxin CagA and translocating VacA. The present study investigated the inhibitory action of piperine on H. pylori growth and adhesion.

Methods: Inhibition of H. pylori growth was determined by the broth macrodilution method, and adhesion to gastric adenocarcinoma cells validated by urease assay. Motility test was performed by motility agar and the expression of adhesion gene and flagellar gene in response to the piperine treatment was assessed by RT-PCR and immunoblotting.

Results: Administrated piperine suppressed the level of H. pylori adhesion to gastric adenocarcinoma cells in a dose dependent manner and the inhibition was statistically significant as determined by Student's t-test. In addition, piperine treatment effects on the flagellar hook gene flgE and integral membrane component of the export apparatus gene flhA expression to be suppressed and piperine diminished the H. pylori motility.

Conclusions: flhA, encodes an integral membrane component of the export apparatus, which is also one of the regulatory protein in the class 2 genes expression and flgE is one of them that encodes hook part of the flagella. Suppression of both genes, leads to less motility results in the organism attracted less towards to the gastric epithelial cells might be the possible reason in the adhesion inhibition. To our knowledge, this is the first report published on the inhibitory effects of piperine against the adhesion of H. pylori to gastric adenocarcinoma cells.