Anti-Nociceptive and Anti-Inflammatory Activities of the Hydroethanolic Extract of the Leaf of Clerodendrum polycephalum (Lamiaceae)

Abstract

Background-The mainstay of the treatment of pain and inflammation are opioids, steroids, and non-steroidal anti-inflammatory drugs. Though, they are effective and readily available with negative and unpleasant effects, more importantly, hepatotoxicity and nephrotoxicity. Thus, the need for safer and effective therapy in the management of pain and inflammation. Objective-The work sought to investigate the anti-nociceptive and anti-inflammatory activities of the hydro-ethanolic leaf extract of Clerodendrum polycephalum (HeCP) in animals. Methods-HeCP (100, 200 or 400 mg/kg, p.o.) given to mice, 1 h before administer of acetic acid (0.6% v/v, i.p.), formalin (1%v/v, intraplantar) or capsaicin (1% w/v, intraplantar) for nociceptive behavior in mice while carrageenan (1% w/v in saline, intraplantar) or cotton pellet (20 mg implanted into both groin) to induce acute or chronic inflammation in rats. Results-HeCP (100 -400 mg/kg, p.o.) reduced mean writhes number, duration of paw licking or biting in the acetic acid, formalin and capsaicin models, respectively, in mice. However, the initial treatment of mice with L-NNA (neuronal nitric oxide synthase inhibitor), naloxone (opioid receptor antagonist), or glibenclamide (ATP-sensitive K + channel blocker) prevented HeCP induced anti-nociception in mice. In contrast, the initial treatment of mice with, sulpiride (dopamine D 2 -receptor antagonist) failed to reverse HeCP-induced antinociception. In the aspect of anti-inflammatory activity, HeCP caused significantly but not dose-dependent inhibition of edema development in carrageenan-induced inflammation and cotton pellet-induced granuloma formation in rats. Conclusion-Findings from this work indicates that the hydroethanolic leaf extract of Clerodendrum polycephalum has anti-nociceptive and anti-inflammatory possibly due to its polyphenolic constituents.