Effect of silymarin on different acute inflammation models and on leukocyte migration.

In-vivo anti-inflammatory activity of silymarin was tested in different acute inflammation experimental models. In carrageenan-induced paw oedema in rats, silymarin given orally reduced in a dose-dependent manner the food-pad abscesses (ED50 = 62.42 mg kg-1). In xylene-induced ear mouse inflammation, silymarin applied topically was more effective than administered intraperitoneally, with effects comparable with those of indomethacin. Silymarin also produced a dose-dependent inhibition of leukocyte accumulation in inflammatory exudates following intraperitoneal injection of carrageenan in mice; silymarin significantly reduced the number of neutrophils. Silymarin was unable to inhibit phospholipase A2 in an in-vitro assay. Besides its known anti-oxidative properties and its ability to act as a radical scavenger, these results suggest that silymarin exerts an important anti-inflammatory action in-vivo by reducing oedema with the effect markedly influenced by the inhibition of neutrophil migration into the inflamed site.