Researchers from the Netherlands tested the capacity of several genetically distinct Helicobacter pylori strains to form carcinogenic N-nitrosamines.
Both N-nitroso compounds and colonization with H. pylori represent known risk factors for the development of gastric cancer.
Endogenous formation of N-nitroso compounds is thought to occur predominantly in acidic environments, such as the stomach.
At neutral pH, bacteria can catalyze the formation of N-nitroso compounds.
Bacteria were grown in the presence of 0-1000 µM morpholine and nitrite (in a 1:1 molar ratio), at pH 7, 5, and 3.
| Further in vivo studies are needed to confirm these results.
| Helicobacter |
Incubation of Neisseria cinerea (positive control) with 500 µM morpholine and 500 µM nitrite resulted in a significant increase in formation of N-nitrosomorpholine.
However, the team found that there was no significant induction of N-nitrosomorpholine formation by any of the H. pylori strains, at any of the 3 pH conditions.
Author I. T. M. Vermeer, of Maastricht University, commented on behalf of the group, "H. pylori does not induce formation of the carcinogenic N-nitrosomorpholine in vitro.
"The previously reported weak nitrosation capacity of H. pylori is not sufficient to nitrosate the more difficultly nitrosatable morpholine. This probably also holds true for other secondary amines."
"These results imply that the increased incidence of gastric cancer formation that is associated with gastric colonization by H. pylori is unlikely to result from the direct induced formation of carcinogenic nitrosamines by the bacterium.
"However, this has to be further confirmed in in vivo studies," it was concluded.