Role of Salviae Miltiorrhizae Radix extract and its compounds in enhancing nitric oxide expression.

Excessive production of nitric oxide (NO) and its peroxidant product, peroxynitrite, has been implicated in the pathology of acute and chronic renal failure, and inhibitors of NO production have been shown to exert protective and ameliorative effects against renal epithelial cell damage mediated by enhanced generation of NO. Salviae Miltiorrhizae Radix has exhibited a beneficial effect in the improvement of renal failure. In order to clarify the mechanism responsible, we investigated whether Salviae Miltiorrhizae Radix extract and several of its related compounds, including caffeic acid and its polymers which were isolated by our research group, can regulate the generation and release of NO. The results demonstrated that Salviae Miltiorrhizae Radix extract and these compounds suppressed NO effectively in the systems employing activated macrophages and the arginine-hydrogen peroxide, and that, furthermore, the activity shown by the compounds was higher than that shown by the extract. In addition, direct scavenging of NO was also observed. The present findings suggest that Salviae Miltiorrhizae Radix extract and its compounds are potent NO inhibitors, and that their inhibitory effect on the generation and release of NO may contribute to the previously reported pharmacological effect of Salviae Miltiorrhizae Radix in improving renal function.