Antinociceptive, anti-inflammatory and antiulcerogenic activities of ethanol root extract of Strophanthus hispidus DC (Apocynaceae)

Abstract

Strophanthus hispidus DC (Apocynaceae) is a medicinal plant widely used in traditional African medicine in the treatment of rheumatic afflictions, ulcer, conjunctivitis, leprosy and skin diseases. This study sought to investigate the antinociceptive, anti-inflammatory and antiulcer properties of the ethanol root extract of S. hispidus. Antinociceptive activity was evaluated using acetic acid-induced writhing and formalin tests in mice. The carrageenan- and egg albumin-induced rat paw edema tests were used to investigate the anti-inflammatory actions, whereas the antiulcer activity was investigated using ethanol-, HCl- and pyloric ligation-induced gastric ulcer models in rats. S. hispidus [100-800 mg/kg orally (po)] produced significant (p<0.05) inhibition of writhing reflex with peak effect of 74.13% inhibition observed at 800 mg/kg. Similarly, S. hispidus significantly (p<0.05) attenuated formalin-induced early and late phase of nociception with peak effect of 61.84% and 89.43%, respectively, at 200 mg/kg. S. hispidus (25-800 mg/kg po) caused significant (p<0.05) inhibition of edema development in the carrageenan and egg albumin models with peak effect (93.40% and 90.10% inhibition of edema formation) observed at 50 mg/kg. With respect to antiulcer activity, S. hispidus (100-800 mg/kg) showed potent antiulcer activity with respective peak effects of 96% (ethanol-induced), 99% (HCl-induced) and 70.60% inhibition of ulcer. The findings in this study suggest that the ethanol root extract of S. hispidus possesses antinociceptive, anti-inflammatory and antiulcerogenic activities. This justifies the use of the extract in folklore medicine for the treatment of ulcer and inflammatory disorders.