Effect of lupeol from Vernonia glaberrima (Asteraceae) on pain and inflammation

Background Steroids have been reported to possess analgesic and anti-inflammatory activities, and Vernonia glaberrima also possesses analgesic and anti-inflammatory properties. Aim The aim of the study was to evaluate the effect of lupeol isolated from the n-hexane soluble fraction of the methanol leaf extract of V. glaberrima on pain and inflammation. Method Lupeol was re-isolated from the leaf of V. glaberrima by using chromatographic procedures; it was subjected to analgesic and anti-inflammatory studies by using acetic acid-induced writhing test in mice and formalin-induced pain and inflammation in rats, respectively. The intraperitoneal lethal dose (LD[sub.50]) of lupeol was determined by using Lorke's method. Results The results of the study showed that lupeol significantly (p < 0.05) decreased writhing response at doses 12.5 mg/kg, 25.0 mg/kg and 50.0 mg/kg corresponding to percentage inhibition of 83.60%, 83.63% and 80.02%, respectively. This was higher than piroxicam, the standard drug (73.8%), at 10 mg/kg. The compound was also able to significantly (p < 0.05) reduce nociceptive response in both phases of the formalin test, and there was a remarkable reduction of oedema by the compound at the second, third and fourth hours. The median LD[sub.50] of the compound was estimated to be greater than 5000 mg/kg. Conclusion The findings of this study indicated that lupeol from the leaf of V. glaberrima has good analgesic and anti-inflammatory activity that validates the ethnomedicinal use of the plant in the treatment of pain and inflammatory conditions.