NEW THIONITRITES - SYNTHESIS, STABILITY, AND NITRIC-OXIDE GENERATION

In order to study the influence of substitutions at the alpha and beta carbon atoms on the stability of the S-NO bond, water-soluble thionitrites RSNO have been synthesized by nitrosation of cysteamine and mercaptoethanol derivatives and characterized. H-1 and C-13 NMR spectroscopies have proven to be excellent probes for the nitrosation of thiols. In water, at physiological pH, the compounds decomposed into nitric oxide NO and the corresponding disulfides. The rate at which NO was released was very sensitive to modifications at the alpha and beta carbon atoms. Tertiary thionitrites were more stable than primary thionitrites. The beta-substituents decreased the rates of decomposition in the following order: OH > NHCOCH3 > NH3+. S-Nitrosocysteamine derivatives were greatly stabilized at low pH. The compounds described here might be convenient and useful as vehicles for spontaneous generation of nitric oxide in biological systems, at rates that can be finely tuned and controlled over a wide range.