oxidized by ONOO– to BC-OH. However, in this reaction 3-benzothiazol-2-yl-chromen-2-one (BC-H) is formed in the minor pathway, as a peroxynitrite-specific product. BC-OH is also formed in the reaction of BC-BA with HOCl, and subsequent reaction of BC-OH with HOCl leads to the formation of a chlorinated phenolic product, which could be used as a specific product for HOCl. We conclude that BC-BA shows
最近开发了含有对氧化剂敏感的硼酸酯基团的香豆素衍生物,用于荧光检测炎症氧化剂。在此,我们报道了 3-(2-苯并噻唑基)-7-香豆素硼酸频哪醇酯 ( BC-BE ) 的合成和表征,作为检测过氧亚硝酸盐 (ONOO – ) 的荧光探针,具有高稳定性和快速检测能力。响应时间。 BC-BE探针在磷酸盐缓冲液中水解为 3-(2-苯并噻唑基)-7-香豆素硼酸 ( BC-BA ),即使在延长的孵育时间(24 小时)后,该物质在溶液中仍保持稳定。 BC-BA被 H 2 O 2缓慢氧化,形成酚类产物 3-苯并噻唑-2-基-7-羟基-苯并吡喃-2-酮 ( BC-OH )。另一方面, BC-BA探针与ONOO -快速反应。 BC-BA探头检测ONOO的能力是使用真实的ONOO和共同生成 O 2 • -和• NO 稳态通量的系统来测量的。 BC-BA被 ONOO –氧化为BC-OH 。然而,在此反应中,3-苯并噻唑-2-基-苯并吡喃-2-酮
Nitroxyl (HNO) Reacts with Molecular Oxygen and Forms Peroxynitrite at Physiological pH
boronate probes were detected under these conditions. Using the competition kinetics method and a set of HNO scavengers, the value of the second order rate constant of the HNO reaction with oxygen (k = 1.8 x 10(4) m(-1) s(-1)) was determined. The rate constant (k = 2 x 10(4) m(-1) s(-1)) was also determined using kinetic simulations. The kinetic parameters of the reactions of HNO with selected thiols, including
硝基的质子化一电子还原产物硝基氧(HNO)仍然是一个神秘的活性氮物质。其化学反应性和生物学活性仍未完全理解。HNO供体显示出与NO供体不同的生物学效应。尽管文献中描述了HNO与分子氧的反应性,但尚未明确鉴定该反应的产物。在这里,我们报告在有氧条件下在生理pH水溶液中HNO供体的分解导致形成过氧亚硝酸盐(ONOO(-))作为主要中间体。我们已经借助硼酸酯探针(例如香豆素7-硼酸或荧光素甲酯的4-硼烷苄基衍生物)专门检测和定量了ONOO(-)。除了主要的酚醛产品外,在这些条件下检测到过氧亚硝酸盐特定的硼酸盐探针氧化副产物。使用竞争动力学方法和一组HNO清除剂,确定了HNO与氧气反应的二级速率常数(k = 1.8 x 10(4)m(-1)s(-1))的值。速率常数(k = 2 x 10(4)m(-1)s(-1))也使用动力学模拟确定。报道了HNO与选定的硫醇,包括半胱氨酸,二硫苏糖醇,N-乙酰半
Boronic acid with high oxidative stability and utility in biological contexts
作者:Brian J. Graham、Ian W. Windsor、Brian Gold、Ronald T. Raines
DOI:10.1073/pnas.2013691118
日期:2021.3.9
enhance oxidative stability. We found that a boralactone, in which a carboxyl group serves as an intramolecular ligand for the boron, increases stability by 104-fold. Computational analyses revealed that the resistance to oxidation arises from diminished stabilization of the p orbital of boron that develops in the rate-limiting transition state of the oxidation reaction. Like simple boronicacids and boronate
尽管它们具有理想的属性,但硼酸在生物环境中的影响很小。一个重要的问题是它们的氧化不稳定性。在生理 pH 值下,苯硼酸及其硼酸酯被活性氧以与硫醇相当的速率氧化。在考虑氧化反应的机理和动力学后,我们推断硼上电子密度的降低可以提高氧化稳定性。我们发现硼内酯,其中羧基作为硼的分子内配体,稳定性增加了 10 4-折叠。计算分析表明,抗氧化性是由于硼在氧化反应的限速过渡态中形成的 p 轨道的稳定性减弱而引起的。与简单的硼酸和硼酸酯一样,硼酸内酯与 1,2-二醇(如糖类中的那些)共价且可逆地结合。然而,其复合物的动力学稳定性至少高出 20 倍。硼酸内酯还与蛋白质中的丝氨酸侧链共价结合。这些属性赋予硼内酯在化学生物学和药物化学领域前所未有的效用。
Synthetic exploration of electrophilic xanthylation <i>via</i> powerful <i>N</i>-xanthylphthalimides
Similarly, xanthamide and thioxanthate groups could also be transformed into desired nucleophiles via this electrophilic reagent strategy. The broad substrate scope, excellent functional group compatibility and late-stage functionalization of bioactive or functional molecules made them very attractive as general reagents which will allow rapid incorporation of SC(S)R (R = OEt, Oalkyl, NEt2 and SEt) into