Characterization of the Reaction between Sialic Acid (N-Acetylneuraminic Acid) and Hydrogen Peroxide(Biochemistry)

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In a previous report, we had demonstrated the antioxidant activity of the sialic acid N-acetylneuraminic acid (Neu5Ac, NANA). This activity can counteract the cytotoxicity of hydrogen peroxide (H_2O_2), and the antitoxicity is a result of a direct chemical reaction, whereby NANA reduces H_2O_2 in the culture media. The influence of the potential of hydrogen (pH) and temperature in this reaction was investigated. The reaction velocity is remarkably less at low pH and/or low temperature, but it increases with these parameters. Furthermore, the reaction product generated in the slow reaction under acidic conditions (pH 3.1) was analyzed. We detected 4-(acetyl-amino)-2,4-dideoxy-D-glycero-D-galacto-octonic acid (ADOA) as the decarboxylation product of NANA; this is the same product we previously obtained in a faster reaction at neutral pH (pH 7.5). Furthermore, ADOA was generated not only from the reaction with the NANA monomer but also from that with α(2→8) homodimer of NANA (DP2). Thus, it can be considered that the reaction between NANA and H_2O_2 can occur under various pH conditions and for NANA residues in a glycochain.
公益社団法人日本薬学会の論文
2007-03-01