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 thionit rites RSNO have been synthesized by nitrosation of cysteamine and merc aptoethanol derivatives and characterized. H-1 and C-13 NMR spectrosco pies have proven to be excellent probes for the nitrosation of thiols. In water, at physiological pH, the compounds decomposed into nitric o xide NO and the corresponding disulfides. The rate at which NO was rel eased was very sensitive to modifications at the alpha and beta carbon atoms. Tertiary thionitrites were more stable than primary thionitrit es. 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 nit ric oxide in biological systems, at rates that can be finely tuned and controlled over a wide range.