Antinociceptive, anti-inflammatory and antipyretic activities of the leaf methanol extract of Ruta graveolens L. (Rutaceae) in mice and rats

Ruta graveolens has been used to treat toothache, earache, rheumatism and fever with little scientific evidence corroborating these uses.The leaf methanol extract of Ruta graveolens was evaluated for antinociceptive activity using the acetic acid writhing and hot-plate tests in mice, also anti-inflammatory and antipyretic activities using the carrageenan-induced oedema and E. coli-induced pyrexia tests in rats, respectively.R. graveolens (100 mg/kg, i.p.), significantly reduced the number of acetic acid-induced writhes by 54 %. R. graveolens (400 mg/kg, i.p.), significantly delayed the reaction time in mice to thermal stimulation 15, 30, 45, and 60 min after treatment. Combined treatment of the lowest and sub-effective doses of the leaf methanol extract (25 mg/kg, i.p.), and indomethacin (10 mg/kg, i.p.) significantly reduced the number of acetic acid-induced writhes in mice. The leaf methanol extract of R. graveolens (50 - 400 mg/kg, i.p.), significantly reduced carrageenan-induced oedema over the 4 h period of testing. Combined treatment of the lowest doses of R. graveolens (25 mg/kg, i.p.) and indomethacin (2 mg/kg, i.p.) produced a significant reduction in carrageenan-induced oedema over the 4 h period of testing. R. graveolens (100 -400 mg/kg, i.p.) significantly reduced E. coli-induced pyrexia over the 5 h period of testing. Given together, the lowest dose of R. graveolens (25 mg/kg, i.p.) and pentoxifylline (10 mg/kg, i.p.) produced a significant reduction in pyrexia induced by E. coli (50 µg/kg, i.m.) over the 5 h period of measurement. The LD50 value obtained for R. graveolens was greater than 4000mg/kg (p.o), suggesting that the plant species may be safe in or nontoxic to mice.The data obtained indicate that R. graveolens has antinociceptive, anti-inflammatory and antipyretic activities, justifying the use of the plant species by traditional medicine practitioners in the management and treatment of pain, inflammation and fever.