Investigation of the chemical structure and biological activity of oligosaccharides isolated from rough-type Xanthomonas campestris pv. campestris B100 lipopolysaccharide

The rough-type lipopolysaccharide, (LPS) of the phytopathogenic bacterium Xanthomonas campestris pv. campestris B 100 was isolated utilizing the hot phenol-water method and successively de-acylated by treatment with hydrazine and hot potassium hydroxide. Four compounds were separated by preparative high-performance anion-exchange chromatography and studied by sugar analysis and by ID and 2D homonuclear and heteronuclear H-1-, C-13- and P-31-NMR spectroscopy as well as ESI FT-MS. The two main products were a heptasaccharide and a pentasaccharide of the structures (alpha-D-Manp-(1 -> 3)-alpha-D-Manp-(1 -> 4)-beta-D-Glcp-(1 -> 4)-alpha-D-Manp-3P-(1 -> 5)-alpha-Kdo-(2 -> 6)-beta-D-GlcpN-4P-(1 ->)6)-alpha-D-GlcpN-1P (1) and beta-D-Glcp-(1 -> 4)-(alpha-D-Manp-3P-(1 -> 5)-alpha-Kdo-(2-6)-alpha-D-GlcpN-4P-(1 -> 6)-alpha-D-GlcpN-1P (2), respectively. The products in smaller amounts were a heptasaccharide and pentasaccharide possessing the above structures plus a phosphate group at C-4 of the Kdo residue (compounds 3 and 4). Both, heptasaccharide 1 and pentasaccharide 2 were able to induce an oxidative burst in cell cultures of the non-host plant tobacco.