Characterization of the Reaction between Sialic Acid (N-Acetylneuraminic Acid) and Hydrogen Peroxide
作者:Ryosuke Iijima、Hideyo Takahashi、Shiro Ikegami、Masatoshi Yamazaki
DOI:10.1248/bpb.30.580
日期:——
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 (H2O2), and the antitoxicity is a result of a direct chemical reaction, whereby NANA reduces H2O2 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-(acetylamino)-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 H2O2 can occur under various pH conditions and for NANA residues in a glycochain.
在之前的一份报告中,我们证实了神经氨酸 N-乙酰神经氨酸(Neu5Ac,NANA)的抗氧化活性。这种活性可以抵消过氧化氢(H2O2)的细胞毒性,其抗毒性是 NANA 在培养基中还原 H2O2 的直接化学反应的结果。我们研究了氢电位(pH 值)和温度对这一反应的影响。在低 pH 值和/或低温条件下,反应速度明显降低,但随着这些参数的升高,反应速度会加快。此外,还分析了在酸性条件(pH 值为 3.1)下缓慢反应生成的反应产物。我们检测到 4-(乙酰氨基)-2,4-二脱氧-<小>D小>-甘油-<小>D小>-半乳辛酸(ADOA)是 NANA 的脱羧产物;这与我们之前在中性 pH 值(pH 7.5)下快速反应得到的产物相同。此外,ADOA 不仅与 NANA 单体反应生成,还与 NANA 的 α(2→8)同源二聚体(DP2)反应生成。因此,可以认为 NANA 和 H2O2 之间的反应可以在不同的 pH 值条件下发生,也可以在糖链中的 NANA 残基上发生。