One major component of the Salmonella enterica sv. Minnesota Re deep rough mutant (strain R595) lipopolysaccharide is hepta-acyl lipid A (LAhepta). In a recent publication [Tanamoto K-l, Azurru S. Salmonella-type heptaacylated lipid A is inactive and acts as an antagonist of lipopolysaccharide action on human line cells. Journal of Immunology 2000; 164: 3149-3156] the corresponding synthetic hepta-acyl lipid A (compound 516) was reported to be agonistically inactive but to rather suppress pro-inflammatory activation by the endotoxic hexa-acyl lipid A (LAhexa, compound 506) and S-form LPS from Escherichia coli in the human macrophage-like cell lines THP-1 and U937. These results, however, were in contrast to previous findings with human mononuclear cells (hMNC) isolated from peripheral blood, in which compound 516 was found to be an agonist, expressing low, but significant, cytokine-inducing activity as compared to LAhexa. We have investigated the structure of natural LAhepta from the S. enterica sv. Minnesota Re deep rough mutant strain (R595) by TLC immunoblot, MALDI-TOF mass spectrometry and NMR spectroscopy. Using these techniques, the structural identity between Lahepta and the synthetic compound 516 was confirmed. In corroboration of previous findings with studies employing compound 516, purified LAhepta was found to induce the production of TNF-a, IL-1b and IL-6 in hMNC, thus displaying moderate agonistic activity. Furthermore, we showed that LAhepta agonistically activated nuclear translocation of NF-kB in THP-1 cells, thus clearly ruling out the possibility that LAhepta is an antagonist and that its biological activity is influenced by the type of human myeloid cells used for testing endotoxicity (hMNC versus THP-1 cells).

Lipopolysaccharide, LPS, structure, strain, lipid A, Salmonella enterica, Re

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
0,2,3	lXPam
0,2	lR3HOMyr
0,3	lR3HOMyr
0,6,2,3	lXLau
0,6,2	lR3HOMyr
0,6,3,3	lXMyr
0,6,3	lR3HOMyr
0,6,4	P
0,6	bDGlcpN	102.9	55.1	74.4	72.5	76.2	61.2
0	aDGlcpN	95.2	52.8	74.6	69.4	73.5	69.7
	P


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
0,2,3	lXPam
0,2	lR3HOMyr
0,3	lR3HOMyr
0,6,2,3	lXLau
0,6,2	lR3HOMyr
0,6,3,3	lXMyr
0,6,3	lR3HOMyr
0,6,4	P
0,6	bDGlcpN	4.51	3.78	5.06	4.16	3.34	3.82
0	aDGlcpN	5.34	4.06	5.09	3.40	4.01	3.74-3.95
	P


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
0,2,3	lXPam
0,2	lR3HOMyr
0,3	lR3HOMyr
0,6,2,3	lXLau
0,6,2	lR3HOMyr
0,6,3,3	lXMyr
0,6,3	lR3HOMyr
0,6,4	P
0,6	bDGlcpN	102.9/4.51	55.1/3.78	74.4/5.06	72.5/4.16	76.2/3.34	61.2/3.82
0	aDGlcpN	95.2/5.34	52.8/4.06	74.6/5.09	69.4/3.40	73.5/4.01	69.7/3.74-3.95
	P

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

CCCCCCCCCCCCCCCC(=O)O[C@H](CCCCCCCCCCC)CC(=O)N[C@H]1[C@@H](OP(=O)(O)O)O[C@H](CO[C@@H]2O[C@H](CO)[C@@H](OP(=O)(O)O)[C@H](OC(=O)C[C@@H](CCCCCCCCCCC)OC(=O)CCCCCCCCCCCCC)[C@H]2NC(=O)C[C@@H](CCCCCCCCCCC)OC(=O)CCCCCCCCCCC)[C@@H](O)[C@@H]1OC(=O)C[C@H](O)CCCCCCCCCCC

2036.81 g/mol (C₁₁₀H₂₀₈N₂O₂₆P₂)