The colonic mucosa of patients with active UC has high levels of prostaglandin E2 (PGE2) and leukotriene B4 (LTB4). Mesalazine can inhibit the synthesis of prostaglandins in a dose-dependent manner and reduce the release of PGE2 in human colonic mucosa.

In addition, mesalazine can also inhibit the lipoxygenase activity of neutrophils. The addition of mesalazine to culture human colonic mucosal cells can produce dose-response inhibition of two important inflammatory mediators, chemotaxis LTB4 and leukotrienes.

At high doses, mesalazine can inhibit certain functions of human neutrophils, such as migration, degranulation, phagocytosis and synthesis of oxygen free radicals. In addition, mesalazine can also inhibit the synthesis of platelet activating factor (PAF), which plays an important role in the occurrence of inflammation. Works better on the connective tissue of the inflamed bowel wall. For ulcerative colitis, ulcerative proctitis and Crohn's disease. It has a significant inhibitory effect on the inflammation of the intestinal wall. Mesalazine can inhibit the synthesis of prostaglandins that cause inflammation and the formation of the inflammatory mediator leukotrienes, thereby significantly inhibiting the inflammation of the intestinal mucosa.