Anti-nociceptive and anti-inflammatory activities of methanol root extract of Andropogon gayanus Kunth (Poaceae) in rodents

Abstract

Andropogon gayanus is widely used in traditional medicine for various ailments such as postpartum pain, bronchitis and oedema. Objective: This study evaluated the anti-nociceptive and anti-inflammatory activities of methanol root extract of A. gayanus in experimental rodents. Methods: Phytochemical screening tests and acute toxicity studies were carried out. Analgesic activity using acetic acid-induced writhing response and hot plate test in mice, formalin-induced pain and carrageenan-induced paw oedema in rats were evaluated at doses of 250, 500 and 1000 mg/kg of the extract. Results: Oral median lethal dose was >5000 mg/kg in both mice and rats. The extract significantly (p<0.01) decreased the number of writhing movements at all tested doses. It also significantly (p<0.05) increased the mean reaction times. A significant (p<0.05) decrease in mean pain scores was also observed in both phases of the formalin test at 1000 mg/kg. The extract at 1000 mg/kg significantly (p<0.05) reduced the oedema at the 1st hour, while at the 5th hour, all doses tested significantly reduced the oedema. Conclusion: The methanol root extract of Andropogon gayanus possesses antinociceptive and anti-inflammatory activitiesAndropogon gayanus is widely used in traditional medicine for various ailments such as postpartum pain, bronchitis and oedema. Objective: This study evaluated the anti-nociceptive and anti-inflammatory activities of methanol root extract of A. gayanus in experimental rodents. Methods: Phytochemical screening tests and acute toxicity studies were carried out. Analgesic activity using acetic acid-induced writhing response and hot plate test in mice, formalin-induced pain and carrageenan-induced paw oedema in rats were evaluated at doses of 250, 500 and 1000 mg/kg of the extract. Results: Oral median lethal dose was >5000 mg/kg in both mice and rats. The extract significantly (p<0.01) decreased the number of writhing movements at all tested doses. It also significantly (p<0.05) increased the mean reaction times. A significant (p<0.05) decrease in mean pain scores was also observed in both phases of the formalin test at 1000 mg/kg. The extract at 1000 mg/kg significantly (p<0.05) reduced the oedema at the 1st hour, while at the 5th hour, all doses tested significantly reduced the oedema. Conclusion: The methanol root extract of Andropogon gayanus possesses antinociceptive and anti-inflammatory activities. Keywords: