Article Proposes New Approach for Specific Detection of Peroxynitrite

An international collaboration among scientists in the Department of Biophysics at the Medical College of Wisconsin and Lodz University of Technology in Poland resulted in publication of the article, "Phenyl Radical-Mediated Fluorogenic Cyclization for Specific Detection of Peroxynitrite," in Analytical Chemistry. The abstract follows:

Peroxynitrite (ONOO^–), a biological oxidizing and nitrating species responsible for post-translational modification of cellular proteins, has been implicated in numerous pathologies carrying an inflammatory component. Specific detection of ONOO^– in biological systems remains a challenge, and boronates are regarded as the most promising class of probes for the detection and quantitation of ONOO^–. Oxidation of boronate probes by ONOO– results in the formation of minor ONOO–-specific products via a pathway involving a phenyl radical-type intermediate, in addition to the major phenolic product. Here, we report fluorogenic cyclization of the phenyl-type radical formed during oxidation of a boronate probe by ONOO^–, with the production of a fluorescent product, and we propose a new approach for the specific detection of ONOO^– based on this observation. We characterized the kinetics and stoichiometry of the reaction of benzophenone-2-boronic acid with ONOO^– and identified 2-hydroxybenzophenone as the major product and fluorenone (FLN) and 2-nitrobenzophenone as the minor ONOO–-specific products. Hydrogen peroxide neither alone nor in the presence of myeloperoxidase and nitrite produces FLN or 2-nitrobenzophenone. FLN can be selectively detected using fluorescence spectroscopy, providing a chemical principle for the development of next-generation probes for ONOO^–, with noninvasive, fluorescence-based detection of ONOO–-specific products. Fluorescence-based monitoring of FLN was successfully applied for the detection of ONOO^– generated in situ from the decomposition of SIN-1, a thermal source of the superoxide radical anion and nitric oxide.

This publication is licensed under CC-BY 4.0. 

Authors of the article comprise Jacek Zielonka, PhD, DSc, assistant professor in the Department of Biophysics at the Medical College of Wisconsin, and Aleksandra Grzelakowska, PhD, and Radosław Podsiadły, PhD, from Lodz University of Technology.

The research was supported by Lodz University of Technology under the programme “Excellence Initiative - Research University” (FU2N, grant no. W3/1P/2022) (AG), the Polish National Agency for Academic Exchange under the Bekker NAWA program (project no. BPN/BEK/2022/1/00219) (AG), and NIH grant R01 CA280746 (JZ).