Anti-inflammatory and analgesic effects of methanol extract of red cultivar Allium cepa bulbs in rats and mice

Abstract Objectives Several cultivars of Allium cepa L. have been studied for anti-inflammatory and analgesic activities but there is inadequate information on such biological activities of the concentrated extracts of the Nigerian grown red cultivar A. cepa bulb. Methods The anti-inflammatory models used in this study were Carrageenan-induced paw oedema and formalin-induced paw lick in rats, while acetic acid-induced abdominal writhing, hot plate reaction, hot water tail flick tests in mice were the analgesic models. Results At 30 min post-induction (pi), the inhibition of paw oedema (62.50%) by 200 mg/kg of methanol extract of red cultivar A. cepa bulb (MERCACB) was significantly (p<0.001) higher than that of indomethacin (15.63%) at 10 mg/kg. The paw oedema inhibition at 60 min pi by MERCACB (76.92%) was significantly higher than that of indomethacin (41.03%). At the early phase of formalin paw-lick test, the pain reaction time (PRT) of rat treated with MERCACB (400 mg/kg) was significantly lower than that of indomethacin and the control groups. The hotplate test revealed that PRT of mice treated with 800 mg/kg of MERCACB were significantly (p<0.01) longer in comparism to indomethacin and control groups. The PRT of mice subjected to thermal pain due to hot water and treated with 800 mg/kg of MERCACB was significantly (p<0.05) longer than that of the control group. Conclusions These findings indicate that MERCACB possesses potent anti-inflammatory and analgesic properties which confirm the traditional use of the plant for the treatment of inflammatory diseases and may be useful as a future therapeutic agent.