title: Synthesis of α-L-rhamnosyl ceramide and evaluation of its binding with anti-rhamnose antibodies.
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.
authors.affiliation: Department of Chemistry, The University of Toledo, 2801 W. Bancroft Street, MS602, Toledo, OH 43606, United States.
authors.forename: David E
authors.initials: DE
authors.lastname: Long
authors.affiliation: Department of Chemistry, The University of Toledo, 2801 W. Bancroft Street, MS602, Toledo, OH 43606, United States.
authors.forename: Partha
authors.initials: P
authors.lastname: Karmakar
authors.affiliation: Department of Medicinal and Biological Chemistry, The University of Toledo, 2801 W. Bancroft Street, MS602, Toledo, OH 43606, United States. Electronic address: katherine.wall@utoledo.edu.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Wall
authors.affiliation: Department of Chemistry, The University of Toledo, 2801 W. Bancroft Street, MS602, Toledo, OH 43606, United States. Electronic address: steve.sucheck@utoledo.edu.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Sucheck
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology*; D001665:Binding Sites; D045744:Cell Line, Tumor; D008223:Lymphoma / Q000276:immunology / Q000378:metabolism; D008358:Mannose / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology; D051379:Mice; D015394:Molecular Structure; D012210:Rhamnose / Q000737:chemistry / Q000276:immunology*
chemical_list: D000906:Antibodies; C000596498:alpha-L-rhamnosyl ceramide; D008358:Mannose; D012210:Rhamnose
keywords: Anti-cancer vaccine; Anti-rhamnose antibody; Glycolipid; Rhamnosyl-ceramide