Effects of sanguiin H-6, a component of Sanguisorbae Radix, on lipopolysaccharide-stimulated nitric oxide production.

The present study was conducted to evaluate the effect of sanguiin H-6, a component of Sanguisorbae Radix, on the production of nitric oxide (NO), using macrophages activated by lipopolysaccharide (LPS). Sanguiin H-6 inhibited nitrite production, taken as an index for NO, in a concentration-dependent fashion. This compound decreased inducible NO synthase (iNOS) activity, with the inhibitory effect at a concentration of 25 microM being equal to that of the known iNOS inhibitor aminoguanidine at 50 microM. However, unlike aminoguanidine, sanguiin H-6 was associated with improved cell viability. Reverse transcription-polymerase chain reaction analysis revealed that the expression of iNOS mRNA in activated macrophages was suppressed by sanguiin H-6 in a concentration-dependent manner. In addition, sanguiin H-6 even at a low concentration showed a clear scavenging effect on the NO generated from sodium nitroprusside (an NO donor). These findings indicate that not only does sanguiin H-6 act directly as an NO scavenger, but it also inhibits NO production in LPS-activated macrophages by the concomitant inhibition of iNOS mRNA induction and enzyme activity.