Pachymoside A A novel glycolipid isolated from the marine sponge Pachymatisma johnstonia

Crude extracts of the North Sea marine sponge Pachymatisma johnstonia showed promising activity in a new assay for inhibitors of bacterial type III secretion. Bioassay-guided fractionation resulted in the isolation of the pachymosides, a new family of sponge glycolipids. A major part of the structural diversity in this family of glycolipids involves increasing degrees of acetylation and differing positions of acetylation on a common pachymoside glycolipid template. All of the metabolites with these variations in acetylation pattern were converted into the same peracetylpachymoside methyl ester (2) for purification and spectroscopic analysis. Pachymoside A (1) is the component of the mixture that has natural acetylation at the eight galactose hydroxyls and at the C-6 hydroxyls of glucose-B and glucose-D. Chemical degradation and transformation in conjunction with extensive analysis of 800 MHz NMR data was used to elucidate the structure of pachymoside A (1).