FEMS Immunol Med Microbiol. 2003 May
15;36(1-2):9-17.
Antibacterial actions of fatty acids and monoglycerides against
Helicobacter pylori.
Sun CQ, O'Connor CJ, Roberton AM.
Source
Department of Chemistry, The University of
Auckland, Private Bag 92019, Auckland, New Zealand.
Abstract
The bactericidal potencies of saturated and
unsaturated fatty acids (FAs) and monoglycerides (MGs) against Helicobacter
pylori were determined following short incubations with freshly harvested cells
over a range of pHs. FAs and their derivatives with an equivalent-carbon number
of 12 were the most potent: lauric acid had a
minimum bactericidal concentration (MBC) at pH 7.4 of 1 mM, myristoleic and linolenic acid were the most
potent unsaturated FAs (MBCs of 0.5 mM, pH 7.4), and monolaurin was the most
potent MG (MBC 0.5 mM). Potencies of saturated FAs were increased sharply by
lowering pH, and a decrease of only 0.5 pH units can cause a change from
non-lethal to lethal conditions. Conversely, the bactericidal action of monolaurin
was not pH-dependent. The bactericidal potencies of unsaturated FAs increased
with degree of unsaturation. When more than one FA or FA plus MGs were present,
their combined action was additive. Urea and endogenous urease did not protect
H. pylori from the bactericidal action of FAs. These
results suggest that H. pylori present in the stomach contents (but not
necessarily within the mucus barrier) should be rapidly killed by the
millimolar concentrations of FAs and MGs that are produced by pre-intestinal
lipase(s) acting on suitable triglycerides such as milk fat.
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