Chemical structure and biological activity of a lipid A component from Helicobacter pylori strain 206

The chemical structure of a lipid A. which was obtained as a minor componen t from lipopolysaccharide of Helicobacter pylori strain 206-1, was determin ed to be a glucosamine beta-(1-6) disaccharide 1-(2-aminoethyl)phosphate ac ylated by (R)-3-hydroxyoctadecanoic acid. (R)-3-hydroxyhexadecanoic acid, a nd (R)-3-(octadecanoyloxy)octadecanoic acid at the 2-, 3- and 2 ' -position s, respectively. Compared with the other major lipid A from the same strain , which was previously reported [Suda Y, Ogawa T, Kashihara W rt al. Chemic al structure of lipid A from Helicobacter pylori strain 206-1 lipopolysacch aride. J Biochem 1997: 121: 1129-1133], the structure was very similar with one exception. An (R)-3-hydroxyhexadecanoic acid was present at the 3-posi tion of the novel lipid A component. The structure is apparently identical to one of the proposals by Moran rt al. [Moran AP. Lindner B, Walsh EJ. Str uctural characterization of the lipid A component of Helicobacter pylori ro ugh- and smooth-form lipopolysaccharides. J Bacteriol 1997; 179: 6453-6463] , who concluded the same structure as the so-called major lipid A from the H. pylori strain NCTC 11637 but without isolating a homogenous component. T he endotoxic properties and pro-inflammatory cytokine-inducing activities o f this novel tetra-acyl type Lipid A were lower than those of previously re ported major tri-acyl type lipid A.