Phenyl Radical-Mediated Fluorogenic Cyclization for Specific Detection of Peroxynitrite

Area of Science:

• Biochemistry
• Chemical Biology
• Analytical Chemistry

Background:

• Peroxynitrite (ONOO-) is a reactive species involved in inflammatory diseases.
• Detecting ONOO- in biological systems is difficult.
• Boronate probes are promising for ONOO- detection.

Purpose of the Study:

• To develop a novel, specific method for detecting peroxynitrite (ONOO-).
• To utilize the ONOO--mediated formation of a phenyl radical intermediate for fluorescence detection.
• To characterize the reaction products of a boronate probe with ONOO-.

Main Methods:

• Investigated the oxidation of benzophenone-2-boronic acid by ONOO-.
• Identified reaction products using spectroscopic techniques.
• Monitored fluorenone (FLN) formation via fluorescence spectroscopy.
• Validated the method for detecting ONOO- generated in situ.

Main Results:

• ONOO- oxidation of the boronate probe yields a phenyl radical intermediate.
• This intermediate undergoes cyclization to form fluorescent fluorenone (FLN).
• FLN and 2-nitrobenzophenone are minor, ONOO--specific products, distinct from the major phenolic product.
• FLN formation is specific to ONOO- and not observed with hydrogen peroxide.

Conclusions:

• A new fluorescence-based detection principle for ONOO- has been established.
• This method relies on the specific detection of the ONOO--generated fluorenone product.
• This approach enables noninvasive, fluorescence-based monitoring of ONOO- in biological contexts.