The Antiinflammatory Activity of N-Hexane Insoluble Fraction of Plantago Lanceolata Leaves and Its Major Compound on Mice

Instead of a normal physiological process as body's response to infection and injury, inflammation is also known to underlay a wide variety of diseases, such as tumors, asthma, arthritis, hepatitis, gastritis, and atherosclerosis. Although many antiinflammatory drugs have been discovered, the efforts to develop antiinflammatory agents are still challenging. Medicinal plants provide a huge compound diversity and have inspired drugs discovery for decades. Plantago lanceolata has been used traditionally to cure various inflammatory-related disorders. Previous study found that dichloromethane extract of P. lanceolata leaves demonstrates in vitro antiinflammatory activity. Here, we evaluated the in vivo antiinflammatory activities of n-hexane-insoluble fraction of P. lanceolata leaves dichloromethane extract (HIFPL) and its isolated major compound.

HIFPL was prepared by n-hexane partition of the dichloromethane extract of P. lancelata leaves to remove chlorophylls and other non-polar inert constituents. The first in vivo experimental model employed mice paw edema induced by carrageenan (s.c.). The reduction of the paw edema and the expression of COX-2 were measured. The effectively of HIFPL as COX-2 inhibitor was also assessed in enzymatic assay. The second in vivo experimental model used mice leukocytes migration induced by thioglycollate (i.p.). The reduction of the leukocytes migration and the level of adhesion molecules were measured in the peritoneum lavage.

We demonstrated that HIFPL (doses 40, 80, 160 mg/kgBW; p.o.) exerts antiinflammatory activities in mice. It decreased the paw edema volume and the COX-2 expression level. Nevertheless, HIFPL showed unselective COX-2 inhibitor as it also inhibited COX-1 with a higher potency. Interestingly, HIFPL effectively inhibited leukocyte migration, at least partly, by inhibiting the expression of MCP-1 and IL-8. We also found that ursolic acid is the major compound in HIFPL. In line with HIFPL, ursolic acid exerted antiinflammatory activity in the mice leukocytes migration assay by lowering the level of MCP-1 and IL-8.