Nω-Hydroxy-L-arginine and Its Homologues. Chemical and Biological Properties. A Review

N ω -Hydroxy-L-arginine (NOHA) is a stable intermediate in NO formation from L-arginine catalyzed by NO synthase (NOS). Apparently, NOHA can be released and serve as a stable reserve NO donor (as a substrate of NOS) or transported and exert its own biological effects. It shows endothelium-dependent as well as endothelium-independent vasorelaxant activity. The latter case indicates that NOHA can be metabolized by pathways independent of NOS. These possibilities are discussed in detail. Of the available NOHA homologues homo-NOHA is a good substrate of NOS while nor-NOHA seems to be a very poor substrate of this enzyme. On the contrary, nor-NOHA exerts arginase inhibitory activity 20 times higher than NOHA whereas homo-NOHA is inactive. Detailed investigation of biological activities of NOHA and its homologues seems to be promising from the pharmacological point of view. A review with 43 references.