Triterpene glycosides from plants for antibody recognition

Structural analysis of oleanane-type saponins from the roots of Wisteria frutescens

Efficient Synthesis of β-Halogeno Protected L-Alanines and Their β-Phosphonium Derivatives.

Abstract Ring opening of oxazolines, prepared from l -serinates, with trimethylsilyl halides (TMSX) led to β-halogeno-N-benzoyl-α-amino esters in good to excellent yields. Quaternization of triphenylphosphine by the β-bromo or -iodo amino esters gave the corresponding β-phosphonium salts in overall yields of up to 93% and with e.e. >96%. Hydrolysis of the ester function afforded the phosphonium salt bearing an N-benzoyl-α-amino acid substituent, with partial racemization. However, the reaction of the TMSX with the carboxylic salt, prepared by saponification of the starting oxazoline ester, furnished the corresponding β-halogeno-N-benzoyl-α-amino acids in 70–95% yields. Quaternization of tri…

Ferrocenyl glycopeptides as electrochemical probes to detect autoantibodies in multiple sclerosis patients' será

Abstract Glycopeptide analogues of CSF114(Glc), modified at N-terminus with new ferrocenyl carboxylic acid and a new ferrocenyl-thiphosphino amino acid, were used to implement a new electrochemical biosensor for autoantibody detection in multiple sclerosis. The ferrocenyl moiety of these "electrochemical probes" did not affect autoantibody recognition both in SP-ELISA and in inhibition experiments. By electrochemical monitoring the interactions of the modified peptides Fc-CSF114(Glc) and 4-FcPhP(S)Abu-CSF114(Glc) with the autoantibodies, we demonstrated that autoantibodies could be detected with a sensitivity comparable to ELISA method. The new electrochemical probes can be proposed to char…

A novel phosphorus–carbon bond formation by ring opening with diethyl phosphite of oxazolines derived from serine

Abstract A new reaction of oxazolines derived from serine with diethyl phosphite leading to ring opening products with P–C bond formation is reported. This reaction, which proceeds under neutral conditions and without the use of any halogenated intermediate, results in a mixture of racemic α- and β-phosphono alanines in an approximate 1:2 ratio, with isolated yields up to 77%. The mechanism involves the rearrangement of the oxazoline into the corresponding α-benzamido acrylate, followed by addition of the diethyl phosphite to the double bond. Since no significant transesterification is observed, this method constitutes a simple route for α- and β-phosphono amino acids bearing suitable prote…

Triterpene glycosides from Blighia welwitschii and evaluation of their antibody recognition capacity in multiple sclerosis

Multiple sclerosis (MS) in a multifactorial autoimmune disease in which reliable biomarkers are needed for therapeutic monitoring and diagnosis. Autoantibodies (autoAbs) are known biomarker candidates although their detection in biological fluids requires a thorough characterization of their associated antigens. Over the past twenty years, a reverse chemical-based approach aiming to screen putative autoantigens has underlined the role of glycans, in particular glucose, in MS. Despite the progress achieved, a lack of consensus regarding the nature of innate antigens as well as difficulties proposing new synthetic glucose-based structures have proved to be obstacles. Here is proposed a strate…

Triterpene Saponins from Wisteria floribunda “macrobotrys” and “rosea”

Five oleanane-type saponins were isolated from two cultivars of Wisteria floribunda (Willd.) DC. (Fabaceae): From the roots of Wisteria floribunda “macrobotrys”, one new oleanane derivative elucidated as 3- O-β-D-xylopyranosyl-(1→2)-β-D-glucuronopyranosyl-22- O-acetyl-3p,22p,24-trihydroxyolean-12-en-30-oic acid, and two known glycosides, and from the roots of Wisteria floribunda “rosea”, two known ones. Their structures were elucidated by a detailed 600 MHz NMR analysis including 1D and 2D NMR (1H, 13C, COSY, TOCSY, ROESY, HSQC, HMBC) experiments and mass spectrometry. Chemotaxonomic conclusions were proposed.

Cytotoxic glycosides from the roots of Weigela x “Bristol Ruby”

International audience; Seven oleanane-type glycosides were extracted and isolated by various chromatographic methods from the roots of Weigela x "Bristol Ruby" (1-7), six previously undescribed (1-6) and a known one (7). Their structures were assigned by spectroscopic analysis mainly 2D NMR and mass spectrometry (ESIMS). Selected triterpenoid glycosides (1-3, 6, 7) displayed a good cytotoxic activity against a mouse colon cancer cell line CT26.

Oleanane-type glycosides from the roots of Weigela florida “rumba” and evaluation of their antibody recognition

Three triterpene glycosides were isolated from the roots of Weigela florida "rumba" (Bunge) A. DC.: two previously undescribed 3-O-β-d-xylopyranosyl-(1→2)-[β-d-xylopyranosyl-(1→4)]-β-d-xylopyranosyl-(1→4)-β-d-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyloleanolic acid (1) and 3-O-β-d-xylopyranosyl-(1→2)-[β-d-glucopyranosyl-(1→4)]-β-d-xylopyranosyl-(1→4)-β-d-xylopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid (2), and one isolated for the first time from a natural source 3-O-β-d-xylopyranosyl-(1→3)-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranosyloleanolic acid (3). Their structures were elucidated mainly by 2D NMR spectroscopic analysis (COSY, …

Synthesis of organometallic glycopeptides and electrochemical studies to detect autoantibodies in multiple sclerosis patients' sera

Feliciana Real-Fernandez, Amelie Chamois-Colson, Jerome Bayardon, Francesca Nuti, Elisa Peroni, Maria R. Moncelli, Rita Meunier-Prest, Sylvain Juge and Anna Maria Papini Laboratory of Peptide & Protein Chemistry & Biology, Polo Scientifico, University of Florence, I-50019 Sesto Fiorentino (FI), Italy; Laboratoire de Synthese et d’Electrosynthese Organometalliques (LSEO), Universite de Bourgogne, 21068, Dijon, France

Oleanane-type saponins from the roots of Wisteria floribunda macrobotrys

Natural Triterpene Glycosides for Antibody Recognition

Multiple sclerosis is an autoimmune disease that affects the central nervous system. The key role of the glycosylation in disease pathogenesis has been previously studied and the synthetic N-glucosylated peptide CSF114(Glc) proved its efficiency in autoantibody recognition in the sera of multiple sclerosis patients. Herein, pure natural triterpene glycosides containing different glycosyl moieties were isolated and tested in multiple sclerosis patientsʼ sera to better understand the role of glycosylation. They were selected taking into account the nature and complexity of their osidic part. Five triterpene glycosides were isolated from several plants with more than 95 % purity. The interacti…