title: Oxidation of sialic acid using hydrogen peroxide as a new method to tune the reducing activity.
abstract: Functionalized sialic acids are useful intermediates to prepare a wide range of biological products. As they often occur at a non-reducing terminal of oligosaccharides, the most used technique to activate them is by periodate-mediated oxidation of their glycerol side chain. Here, we describe an alternative, non toxic, and environmentally-friendly method to activate the sialic acid residues by hydrogen peroxide oxidation. Four oxidative systems involving H2O2, EDTA, iron chloride, and UV light were studied and the products obtained were analyzed by LC-MS and NMR, before and after a derivatization reaction. At first, we observed, for each system, an irreversible decarbonylation reaction at the reducing end. Then, the decarbonylated sialic acid (DSA) was oxidized and fragmented into a mix of carbonyls and carboxyl acids, more or less fast according to the experimental conditions. Analysis of the reaction indicated an apparent radical mechanism and heterolytic alpha-hydroxy-hydroperoxide cleavages. The modest reducing activity was mainly explained as a consequence of over-oxidation reactions.
authors: Université de Lyon, Université Lyon 1, Faculté de Pharmacie-ISPB, EA 4446 Biomolécules Cancer et Chimiorésistances, SFR Santé Lyon-Est CNRS UMS3453-INSERM US7, 8 Avenue Rockefeller, F-69373 Lyon Cedex 8, France; Reaction and Coupling Chemistry Laboratory, MTech, Sanofi Pasteur, 31/33 quai Armand Barbès, 69250 Neuville-sur-Saône, France. Electronic address: christophe.neyra@sanofi.com.
authors: C
authors: C
authors: Neyra
authors: Reaction and Coupling Chemistry Laboratory, MTech, Sanofi Pasteur, 31/33 quai Armand Barbès, 69250 Neuville-sur-Saône, France. Electronic address: joseph.paladino@sanofi.com.
authors: J
authors: J
authors: Paladino
authors: Université de Lyon, Université Lyon 1, Faculté de Pharmacie-ISPB, EA 4446 Biomolécules Cancer et Chimiorésistances, SFR Santé Lyon-Est CNRS UMS3453-INSERM US7, 8 Avenue Rockefeller, F-69373 Lyon Cedex 8, France.
authors: M
authors: M
authors: Le Borgne
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004492:Edetic Acid / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D019158:N-Acetylneuraminic Acid / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D021241:Spectrometry, Mass, Electrospray Ionization; D014466:Ultraviolet Rays
chemical_list: D016877:Oxidants; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D007501:Iron; D019158:N-Acetylneuraminic Acid
keywords: Decarbonylation; Hydrogen peroxide; N-Acetylneuraminic acid; Oxidation; Reductive amination; Sialic acid