Chemistry of N-hydroxy- l-arginine

Abstract

The synthesis of N-hydroxy-l-arginine can be accomplished by a relatively simple and straightforward procedure. Also, a variety of arginine derivatives can be synthesized using minor modifications of this procedure. N-Hydroxy-l-arginine is subject to decomposition under either basic or oxidizing conditions. In fact, one of the dominant chemical features of N-hydroxy-l-arginine (or N-hydroxyguanidines), which would be significant to those interested in exploring its role either as a biosynthetic intermediate in NO generation or as an independently acting species, is its ability to act as a reducing agent. Even a cursory inspection of N-hydroxy-l-arginine indicates that the N-hydroxyguanidine function is electron rich and could be easily oxidized. Oxidation of N-hydroxy-l-arginine is, indeed, facile and can lead to either the release of HNO (from a two-electron oxidation) or the formation of an apparent radical species (from one-electron oxidation). The ability of N-hydroxy-l-arginine to act as a one-electron reducing agent (or hydrogen atom-donor) may be important in the biosynthesis of the NO radical since an odd-electron step is required.17 Regardless, it is likely that N-hydroxyguanidines can act as electron sources and may participate in redox reactions with biological oxidants. The physiological relevance of such processes, however, remains to be determined.