Fmoc-protected iminosugar modified asparagine derivatives as building blocks for glycomimetics-containing peptides Francesca Nuti, a,b Ilaria Paolini, a,b Francesca Cardona, b,c Mario Chelli, a,b Francesco Lolli, a,d Alberto Brandi, b,c Andrea Goti, b,c Paolo Rovero a,e and Anna M. Papini a,b, * a Laboratory of Peptide & Protein Chemistry & Biology, Polo Scientifico e Tecnologico, University of Florence, I-50019 Sesto Fiorentino (FI), Italy b Department of Organic Chemistry ‘‘Ugo Schiff’’, Polo Scientifico e Tecnologico, University of Florence and CNR-ICCOM, Via della Lastruccia 13, I-50019 Sesto Fiorentino (FI), Italy c Laboratorio di Progettazione, Sintesi e Studio di Eterocicli Biologicamente attivi, Polo Scientifico e Tecnologico, University of Florence, I-50019 Sesto Fiorentino (FI), Italy d Department of Neurological Sciences, University of Florence, Viale Morgagni 85, I-50134 Firenze, Italy e Department of Pharmaceutical Sciences, Polo Scientifico e Tecnologico, University of Florence, Via Ugo Schiff 6, I-50019 Sesto Fiorentino (FI), Italy Received 15 November 2006; revised 30 March 2007; accepted 5 April 2007 Available online 10 April 2007 Abstract—CSF114(Glc) is the first synthetic Multiple Sclerosis Antigenic Probe able to identify autoantibodies in a statistically sig- nificant number of Multiple Sclerosis patients. The b-turn conformation of this glucopeptide is fundamental for a correct presen- tation of the epitope Asn(Glc). To verify the influence of sugar mimics in antibody recognition in Multiple Sclerosis, we synthesized Fmoc-protected Asn derivatives containing alkaloid-type sugar mimics. The corresponding glycomimetics-containing peptide deriv- atives of the CSF114-type sequence were tested in competitive and solid-phase non-competitive ELISA on Multiple Sclerosis patients’ sera. Ó 2007 Elsevier Ltd. All rights reserved. 1. Introduction The importance of carbohydrate recognition in biologi- cal events is well established on many experimental find- ings. How post-translational protein modifications, in particular glycosylation, can have a role in the origin of autoimmune responses is still not characterized but almost all of the key molecules involved in innate and adaptive immune responses are glycoproteins. More- over, in the last years, a number of autoimmune diseases have been associated with glycosylation defects. 1 Our interest was to further investigate the role of glyco- syl moiety in autoantibody (auto-Ab) recognition in Multiple Sclerosis (MS) using different glycomimetic derivatives of CSF114 peptide sequence. CSF114(Glc) is a structure-based designed glucosylated peptide, char- acterized by a b-turn, 2 able to identify autoantibodies 3 in a statistically significant number of MS patients com- pared to healthy blood donors and other autoimmune diseases. 4 We demonstrated that the presence of a b-D- glucopyranosyl moiety on an Asn residue at position 7 of CSF114(Glc) is fundamental for auto-Ab recogni- tion. In fact, no Abs could be identified by the corre- sponding unglycosylated peptide sequence. Moreover, the specific autoantibody recognition is most likely dri- ven by direct interactions of the antibody binding site with the Asn-linked sugar moiety and not with the CSF114 peptide sequence. These data let us to assess that in MS, autoantibody recognition is strictly corre- lated with specific glycosylated epitopes. 3 To extend auto-Ab recognition to glycosylated epitopes in MS and to verify the influence of sugar mimics, we 0968-0896/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.bmc.2007.04.007 Keywords: Iminosugars; Glycopeptides; Multiple Sclerosis; Solid-phase peptide synthesis. * Corresponding author. Tel.: +39 055 4573561; fax: +39 055 4573584; e-mail: annamaria.papini@unifi.it Bioorganic & Medicinal Chemistry 15 (2007) 3965–3973