Leaves Aqueous Extract of <i>Boerhavia coccinea</i> Induces Antinociceptive Effect but Increases Nitric Oxide Production in Macrophages

Abstract

Pain treatment is one of the most challenging situations of the modern medicine. To overcome the actual limitations, new strategies should be developed and phytotherapy represents a promising alternative. Boerhavia coccinea is a medicinal plant used for the treatment of pain. The present work was undertaken to evaluate the antinociceptive effects of crude aqueous extract of the leaves of Boerhavia coccinea (AE) on acute pain and examine its mechanism of action. The analgesic effect of AE was evaluated at doses 50, 100, 200 and 400 mg/kg using the formalin-induced nociception in mice. The specific analgesic effect of AE was verified by testing its effect of AE on the sleep induced by diazepam. The anti-inflammatory effects of AE were also tested in vivo (100 and 200 mg/kg) on CFA-induced inflammation and in vitro (1 to 300 μg/ml) on the production of NO by non-activated or activated (LPS, 1 μg/l) macrophages. The effect of AE in non-stimulated macrophages was evaluated in absence and in presence of L-NAME (100 μg/ml) or dexathetasone (30 μg/ml). AE administered orally significantly (p st phase and 90% at the 2nd phase, but did not show any anti-inflammatory effect. AE at 50 mg/kg increased the latency to sleep and reduced sleep duration. AE drastically (p < 0.001) increased the NO production by non-activated or activated macrophages by up to 5654%. L-NAME and dexamethasone potentiated the activation effect of AE on NO production. In conclusion, AE possess potent antinociceptive effect that is not related to any anti-inflammatory activity. Instead, this extract increases the nitric oxide production by an unknown mechanism.