Metabolic stability of superoxide adducts derived from newly developed cyclic nitrone spin traps

Abstract

Reactive oxygen species (ROS) are by-products of aerobic metabolism involved in the onset and evolution of various pathological conditions. Among them, superoxide radical is of special interest as the origin of several damaging species such as H 2 O 2 , hydroxyl radical, or peroxynitrite (ONOO -). Spin trapping coupled with ESR is a method of choice to characterize these species in chemical and biological systems and the metabolic stability of the spin adducts derived from reaction of superoxide and hydroxyl radicals with nitrones is the main limit to the in vivo application of the method. Recently, new cyclic nitrones bearing a triphenylphosphonium or cyclodextrin moiety have been synthesized and their spin adducts demonstrated increased stability in buffer. In the present manuscript, we studied the stability of the superoxide adducts of four new cyclic nitrones in the presence of liver subcellular fractions and biologically relevant reductants using an original set up combining a stoppedflow device and an ESR spectrometer. The kinetics of disappearance of the spin adducts were analyzed using an appropriate simulation program. Our results highlight the interest of new spin trapping agents CD-DEPMPO and CD-DIPPMPO for specific detection of superoxide with high stability of the superoxide adducts in the presence of liver microsomes.3

Synthesis and Characterization of the Perthiatriarylmethyl Radical and Its Dendritic Derivatives with High Sensitivity and Selectivity to Superoxide Radical

“…To test this hypothesis, the detection of O 2 .− by both PST‐NA and DMPO was compared in the presence of various concentrations of ascorbate. Because the O 2 .− spin adduct of DMPO is easily decomposed into the hydroxyl spin adduct, the total concentrations of both spin adducts are used to reflect the trapped O 2 .− levels. As shown in Figure A, the initial total concentration was determined to be approximately 4.6 μ m after 90 s incubation of DMPO (100 m m ) with the X/XO system in PBS.…”

“…A further increase in the ascorbate concentrations (10–20 μ m ) led to much lower initial concentrations and faster decays of the spin adducts, and their EPR signals were not detectable in the presence of 20 μ m ascorbate. Accordingly, ascorbate at relatively high concentrations not only impedes O 2 .− trapping by DMPO, but also promotes the decay of the spin adducts …”

Heteroatom–Heteroatom Bond Formation in Natural Product Biosynthesis

“…191–193 For example, the antiproliferative activity of avrainvillamide (66 , Scheme 10B), a nitrone-containing alkaloid isolated from a strain of Aspergillus , involves the formation of stable covalent adducts between cysteine thiols in proteins and an electrophilic, conjugated nitrone. 194,195 Notwithstanding the scarcity of natural products bearing the nitrone group, the enzymatic synthesis of this functionality has recently been investigated in the context of prenylated indole alkaloids (PIAs) biosynthesis.…”

N-tert-butylmethanimine N-oxide is an efficient spin-trapping probe for EPR analysis of glutathione thiyl radical

“…CDs have a propensity for forming non-covalent inclusion complexes with a variety of hydrophobic organic molecules3536, including nitroxides37383940. The spin-trapping of superoxide anion radical (O 2 −• ) with a series of STs in the presence of β-Me-CD has been shown to proceed with inclusion of the corresponding spin-adducts in the cavity of the cyclodextrin, thus increasing their half-lives414243444546.…”