Synthesis of α-L-rhamnosyl ceramide and evaluation of its binding with anti-rhamnose antibodies

Bioorg Med Chem. 2014 Oct 1;22(19):5279-89. doi: 10.1016/j.bmc.2014.08.002. Epub 2014 Aug 12.

Abstract

An α-L-rhamnosyl ceramide (1, α-L-RhaCer) has been prepared that was recognized by anti-L-rhamnose (anti-Rha) antibodies. During these studies we explored the use of an α-L-rhamnosyl thioglycoside and a trichloroacetimidate as a glycosyl donors. Subsequently, the acceptors desired for glycosylation, 3-O-benzoylazidosphingosine or 3-O-alloxycarbonylsphingosine, were prepared from D-xylose. The thioglycoside donor, 2,3,4-tri-O-acetyl-1-(4-tolyl)thio-α-L-rhamnopyranoside, and the trichloroacetimidate donor, 2,3,4-tri-O-acetyl-1-(2,2,2-trichloroethanimidate)-α-L-rhamnopyranoside, were synthesized in 50% and 78% yield overall, respectively. The synthesis of the glycosylation acceptor employed an addition-fragmentation olefination that was successfully carried out in 53% yield. With the successful synthesis of key intermediates, α-L-RhaCer (1) was prepared without any insurmountable obstacles. Anti-Rha antibodies were prepared in BALB/c mice by immunizing them with rhamnose-ovalbumin (Rha-Ova) with Sigma Adjuvant System (SAS) and the anti-L-Rha antibodies were isolated from the blood sera. Liposomes and EL4 tumor cells were used as model systems to demonstrate the ability of 1 to insert into a lipid bilayer. The interaction of the liposomes or the EL4 cells with α-L-RhaCer (1) and anti-Rha antibodies were investigated by fluorescence microscopy and flow cytometry, respectively, to confirm the ability of glycolipid 1 to be displayed on the tumor cell surface as well as the ability to be recognized by anti-Rha antibodies.

Keywords: Anti-cancer vaccine; Anti-rhamnose antibody; Glycolipid; Rhamnosyl-ceramide.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Antibodies / immunology*
  • Binding Sites
  • Cell Line, Tumor
  • Lymphoma / immunology
  • Lymphoma / metabolism
  • Mannose / analogs & derivatives*
  • Mannose / chemical synthesis
  • Mannose / chemistry
  • Mannose / immunology
  • Mice
  • Molecular Structure
  • Rhamnose / chemistry
  • Rhamnose / immunology*

Substances

  • Antibodies
  • alpha-L-rhamnosyl ceramide
  • Mannose
  • Rhamnose