Anti-nociceptive and anti-inflammatory potentials of Vernonia amygdalina leaf extract via reductions of leucocyte migration and lipid peroxidation

BACKGROUND: Vernonia amygdalina is well known as a medicinal plant in folk medicine as antidiabetic, anthelmintic, antimalarial, laxative/purgative, and expectorant among others. AIM: This study was conducted to investigate the antinociceptive and anti-inflammatory effects of V. amygdalina. MATERIALS AND METHODS: Methanol extract of V. amygdalina leaf (MEVA) was evaluated for antinociceptive effect and possible mechanisms of action in the presence of naloxone (1 mg/kg), atropine (2 mg/kg), and prazosin (1 mg/kg) using acetic acid writhing test in mice. The anti-inflammatory effect was evaluated in carrageenan hind paw edema and carrageenan air pouch models. Protein concentration, malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) assays were carried out for its antioxidative activities in inflammation. Hematoxylin and eosin staining was used to assess the level of inflammation. RESULTS: From the acetic acid writhing test results, MEVA (50,100 mg/kg) showed significant antinociceptive effect. Naloxone, atropine and prazosin did not significantly reverse the antinociceptive effect of MEVA (50 mg/kg). MEVA (50, 100, and 200 mg/kg) showed dose-dependent inhibition of edema (41.4, 63.0, and 68.6%) at 4 h post-carrageenan injection. In the carrageenan air pouch model, MEVA (200 mg/kg) significantly (P < 0.05) reduced infiltrating leukocytes, protein concentration and MDA levels, while GSH and SOD were unaffected. The histological study showed a reduction in the infiltration of inflammatory cells in MEVA-treated groups. CONCLUSION: V. amygdalina showed antinociceptive activity and anti-inflammatory effect via reductions of leukocyte migration and lipid peroxidation.