Synthesis and preliminary biological evaluation of carba analogues from Neisseria meningitidis A capsular polysaccharide

Org Biomol Chem. 2012 Sep 7;10(33):6673-81. doi: 10.1039/c2ob25222h.

Abstract

The Gram-negative encapsulated bacterium Neisseria meningitidis type A (MenA) is a major cause of meningitis in developing countries, especially in the sub-Saharan region of Africa. The development and manufacture of an efficient glycoconjugate vaccine against MenA is greatly hampered by the poor hydrolytic stability of its capsular polysaccharide, consisting of (1→6)-linked 2-acetamido-2-deoxy-α-d-mannopyranosyl phosphate repeating units. The replacement of the ring oxygen with a methylene group to get a carbocyclic analogue leads to the loss of the acetalic character of the phosphodiester and consequently to the enhancement of its chemical stability. Here we report the synthesis of oligomers (mono-, di- and trisaccharide) of carba-N-acetylmannosamine-1-O-phosphate as candidates for stabilized analogues of the corresponding fragments of MenA capsular polysaccharide. Each of the synthesized compounds contains a phosphodiester-linked aminopropyl spacer at its reducing end to allow for protein conjugation. The inhibition abilities of the synthetic molecules were investigated by a competitive ELISA assay, showing that only the carba-disaccharide is recognized by a polyclonal anti-MenA serum with an affinity similar to a native MenA oligosaccharide with average polymerization degree of 3.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carbasugars / chemical synthesis
  • Carbasugars / chemistry*
  • Carbasugars / immunology
  • Enzyme-Linked Immunosorbent Assay
  • Hexosamines / chemical synthesis
  • Hexosamines / chemistry*
  • Hexosamines / immunology
  • Humans
  • Meningitis, Meningococcal / prevention & control
  • Mice
  • Neisseria meningitidis, Serogroup A / chemistry*
  • Neisseria meningitidis, Serogroup A / immunology
  • Oligosaccharides / chemical synthesis
  • Oligosaccharides / chemistry*
  • Oligosaccharides / immunology
  • Phosphates / chemical synthesis
  • Phosphates / chemistry
  • Phosphates / immunology
  • Serum / immunology

Substances

  • Carbasugars
  • Hexosamines
  • Oligosaccharides
  • Phosphates
  • N-acetylmannosamine