Direct oxidation of boronates by peroxynitrite: Mechanism and implications in fluorescence imaging of peroxynitrite

Abstract

In this study, we show that boronates, a class of synthetic organic compounds, react rapidly and stoichiometrically with peroxynitrite (ONOO−) to form stable hydroxy derivatives as major products. Using stopped-flow kinetic technique, we measured the second order rate constants for the reaction with ONOO−, hypochlorous acid (HOCl), and hydrogen peroxide (H2O2), and found that ONOO− reacts with 4-acetylphenylboronic acid nearly a million times (k = 1.6 × 106 M−1 s−1) faster than H2O2 (k = 2.2 M −1 s−1) and over two hundred times faster than HOCl (k = 6.2 × 103 M−1 s−1). Nitric oxide (•NO) and superoxide (O •2−) together, but not alone, oxidized boronates to the same phenolic products. Similar reaction profiles were obtained with other boronates. Results from this study will likely help develop a novel class of fluorescent probes for detection and imaging of ONOO− formed in cellular and cell-free systems.

NADPH Oxidase–Derived Peroxynitrite Drives Inflammation in Mice and Human Nonalcoholic Steatohepatitis via TLR4-Lipid Raft Recruitment

“…52 Our data support the peroxynitrite mechanism owing to the faster-rate kinetics of formation reported for peroxynitrite (10 10 mol per second), but the TLR4-induced NADPH oxidase activation in NASH cannot be ruled out owing to the complex innate immune regulations associated with the pathophysiology of the disease itself. 49 In summary, we show that TLR recruitment into lipid rafts is an early event in both rodent and human NASH pathogenesis. TLR4 recruitment was initiated by NADPH oxidase, and the molecular basis of this early event was dependent on the formation of peroxynitrite.…”

“…48 FBA reacts with peroxynitrite at a rapid rate and stoichiometrically to form phenol (k Z 1.6 Â 10 6 mol per second). 49 FBA is also highly specific to react with peroxynitrite and can be used for inferring the source of tyrosine nitration because it does not inhibit myeloperoxidase-dependent tyrosine nitration. We used the effectiveness of FBA as a candidate drug to attenuate peroxynitrite-mediated recruitment of TLR4 into hepatic lipid rafts.…”

Composition of the redox environment of the endoplasmic reticulum and sources of hydrogen peroxide

“…Further experiments, however, proved their strong reactivity towards peroxynitrite and hypochlorous acid as well [134]. Although the SNAP-tag technology allows ER-targeting of boronate probes [135], they react slowly and irreversibly with hydrogen peroxide.…”

Boronate probes for the detection of hydrogen peroxide release from human spermatozoa

“…•-, nitrous oxide (NO) or hypochlorite ( -OCl) [12,13]. This class of probe has found wide use for the in vivo detection of H 2 O 2 [14], including research into ROS production in cryopreserved mouse spermatozoa [15].…”