Tanshinone IIA from Salvia miltiorrhiza induces heme oxygenase-1 expression and inhibits lipopolysaccharide-induced nitric oxide expression in RAW 264.7 cells.

Tanshinone IIA exerts anti-inflammatory effects and influences electron transfer reaction in mitochondria. In the present study, we demonstrated that tanshinone IIA increased intracellular production of reactive oxygen species (ROS), which in turn induces heme oxygenase-1 (HO-1) expression in RAW 264.7 macrophages. Tanshinone IIA inhibited COX-2 and iNOS expression in lipopolysaccharide-activated RAW 264.7 macrophages. Inhibition of HO-1 or scavenging of CO significantly reversed the inhibition of LPS-stimulated nitrite accumulation by tanshinone IIA, suggesting a novel role of HO-1 in the anti-inflammatory effect of tanshinone IIA.