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-carboxypyrrolidine (CP-H) w ith superoxide radicals and peroxynitrite were studied. The rate const ants were determined as 3.2 x 10(3) and 4.5 x 10(9) M(-1)s(-1), respec tively. It was found that 2mM of spin trap CP-H or 1-hydroxy-2,2,6,6-t etramethyl-4-oxo-pip eri dine (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 quanti fication of peroxynitrite formation. During the reaction of CP-H and T EMPONE-H with superoxide radicals or peroxynitrite the stable nitroxid e radicals 3-carboxyproxyl (CP) and 2,2,6,6-tetramethyl-4-oxo-piperidi noxyl (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 t he reduction of CP by ascorbate was 66-fold slower than corresponding rates of reduction of TEMPONE, Therefore quantification of the formati on of superoxide radicals and of peroxynitrite by CP-H is much less hi ndered 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. (C) 1997 Academic Press.