Anti-nociceptive and anti-inflammatory properties of the leaf extracts of Hedranthera barteri in rats and mice

Abstract

Hedranthera barteri, HB (Apocynaceae) is a shrub in the closed-forest in some parts of West Africa and used among the natives for inflammatory pain relief. This study was carried out to assess the anti-nociceptive and anti-inflammatory effects of its leaf extracts to confirm folkloric claims. Phytochemical screening and acute toxicity were carried out on the leaf of  the plant. Aqueous (AEHB), methanol (MEHB) and chloroform (CEHB)extracts of the leaf were assessed for anti-nociceptive and antiinflammatory properties. The probable mechanism of action of the extracts in analgesia was assessed using naloxone. Student’s t-test was used to test for statistical significance.Phytochemistry of the extracts revealed the presence of alkaloids, cardenolides, saponins and flavonoids. The rats tolerated thermal pain significantly more (P<0.05) with the extracts than the control. The inhibitory rates of the extracts on acetic acid-induced writhing, formalin-induced paw licking (late and early phase) and carrageenan-induced paw oedema when compared with the control were significant. Graded doses of MEHB tolerated thermal pain more significantly (P<0.05), compared with the control. Likewise, the inhibition produced by the graded doses of MEHB on acetic acid-induced writhing,formalin-induced paw licking (early and late phases) and carrageenaninduced paw oedema were significant compared with the control (P<0.05). Pre-treatment with naloxone partially prevented the analgesia induced by MEHB in thermally and chemically induced pains. Hedranthera barteri reduced nociception and inflammation in dose-dependent manner. Interactions with naloxone depicted its partial mediation through opioid receptors. (Afr. J. Biomed. Res. 9:109 - 118, May 2006)

Keywords: Hedranthera barteri, naloxone, nociception, inflammation