Antinociceptive Activities and the Mechanisms of Anti-Inflammation of Asiatic Acid in Mice

Asiatic acid (AA), a pentacyclic triterpene compound in the medicinal plant Centella asiatica, was evaluated for antinociceptive and anti-inflammatory effects. Treatment of male ICR mice with AA significantly inhibited the numbers of acetic acid-induced writhing responses and the formalin-induced pain in the late phase. In the anti-inflammatory test, AA decreased the paw edema at the 4th and 5th h after λ-carrageenan (Carr) administration and increased the activities of catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx) in the liver tissue. AA decreased the nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) levels on serum level at the 5th h after Carr injection. Western blotting revealed that AA decreased Carr-induced inducible nitric oxide synthase (iNOS), cyclooxygenase (COX-2), and nuclear factor-κB (NF-κB) expressions at the 5th h in the edema paw. An intraperitoneal (i.p.) injection treatment with AA also diminished neutrophil infiltration into sites of inflammation as did indomethacin (Indo). The anti-inflammatory mechanisms of AA might be related to the decrease in the level of MDA, iNOS, COX-2, and NF-κB in the edema paw via increasing the activities of CAT, SOD, and GPx in the liver.