Suppression of NO production in activated macrophages in vitro and ex vivo by neoandrographolide isolated from Andrographis paniculata

In this study, we investigated the in vitro and ex vivo suppressive effects of Andrographis paniculata on nitric oxide (NO) production in mouse peritoneal macrophages elicited by bacillus Calmette-Guein (BCG) and, stimulated by lipopolysaccharide (LPS). Incubation of BCG-induced macrophages with the methanol extract of A. paniculata reduced LPS stimulated NO production. The diterpene lactones andrographolide and neoandrographolide were isolated as active components from the extract. These compounds suppressed NO production in a concentration-dependent manner in the concentration range from 0.1 to 100 muM and their IC50 values were 7.9 and 35.5 muM. Neoandrographollide also suppressed NO production by 35 and 40% when the macrophages were collected after oral administration of neoandrographolide at doses of 5 and 25 mg/kg/d and LPS stimulated NO production was examined. However, andrographolide did not reduce NO production on oral administration at the same doses. These results indicate that neoandrographolide, which inhibited NO production both in vitro and ex vivo may play an important role in the use of A. paniculata as an anti-inflammatory crude drug.