Spin trapping of superoxide radicals and peroxynitrite by 1-hydroxy-3-carboxy-pyrrolidine and 1-hydroxy-2,2,6, 6-tetramethyl-4-oxo-piperidine and the stability of corresponding nitroxyl radicals towards biological reductants.
The reactions of new spin trap 1-hydroxy-3-carboxy-pyrrolidine (CP-H) with superoxide radicals and peroxynitrite were studied. The rate constants were determined as 3.2 x 10(3) and 4.5 x 10(9) M-1s-1, respectively. It was found that 2mM of spin trap CP-H or 1-hydroxy-2,2,6,6-tetramethyl-4-oxo-piperidine (TEMPONE-H) provide almost the same spin trapping efficacy. In contrast to TEMPONE-H the reaction of CP-H with peroxynitrite was inhibited by 20 mM DMSO. This simplifies the quantification of peroxynitrite formation. During the reaction of CP-H and TEMPONE-H with superoxide radicals or peroxynitrite the stable nitroxide radicals 3-carboxy-proxyl (CP) and 2,2,6,6-tetramethyl-4-oxo-piperidinoxyl (TEMPONE) are formed. It was found that the rate of reduction of CP by glutathione or by smooth muscle cells was two-fold slower and the reduction of CP by ascorbate was 66-fold slower than corresponding rates of reduction of TEMPONE. Therefore quantification of the formation of superoxide radicals and of peroxynitrite by CP-H is much less hindered by a variety of biological reductants than in case of TEMPONE-H. Thus, CP-H is more suitable for spin trapping of superoxide radicals and peroxynitrite in biological systems than the TEMPONE-H.
Dikalov
S
S
Institute of Chemical Kinetics & Combustion, Novosibirsk, Russia. Dikalov@kinetics.nsk.su
Skatchkov
M
M
Bassenge
E
E
D000818:Animals; D001205:Ascorbic Acid / Q000737:chemistry; D003545:Cysteine / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy; D005978:Glutathione / Q000737:chemistry; D009130:Muscle, Smooth / Q000737:chemistry; D009566:Nitrates / Q000737:chemistry*; D010084:Oxidation-Reduction; D010880:Piperidines / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry; D019097:Spin Trapping; D013481:Superoxides / Q000737:chemistry*
D009566:Nitrates; D010880:Piperidines; D011759:Pyrrolidines; D013481:Superoxides; C039642:peroxynitric acid; C103674:1-hydroxy-2,2,6,6-tetramethyl-4-oxopiperidine; D005978:Glutathione; D003545:Cysteine; D001205:Ascorbic Acid