Effect of piperine on the inhibition of nitric oxide (NO) and TNF-alpha production.

Effect of piperine which is an alkaloid present in plants such as Piper nigrum and Piper longum on the production of nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) level was analyzed using in vitro as well as in vivo systems. The level of nitrite in the LPS stimulated Balb/C mice (95.3 microM) was reduced in the piperine treated animals (25 microM) significantly. Nitrite level in the Concanavalin-A (Con-A) treated control animals (83.1 microM) was also significantly reduced to 18.5 microM in the piperine treated mice. The drastically elevated levels of TNF-alpha in the lipopolysaccharide (LPS) stimulated animals (625.8 pg/mL) was lowered in the piperine treated animals (105.8 pg/mL). Piperine also inhibited the Con-A induced TNF-alpha production. Piperine could inhibit the nitrite production by in vitro activated macrophages (116.25 microM) to the normal level (15.67 microM) at concentration of 5 microg/mL. In vitro L929 bioassay also revealed the inhibition of TNF-alpha production by the piperine treatment.