Studies on phytochemical constituents, toxicity, analgesic and anti-inflammatory activities of Vernonia glaberrima

Vernonia glaberrima has been reportedly used in traditional medicine as an analgesic, anti-inflammatory, antibacterial and antimalarial agent. The analgesic and anti-inflammatory effects of the methanol leaf extract of V. glaberrima were evaluated using acetic acid-induced writhing test in mice and carrageenan-induced paw oedema in rats, respectively. The results of the study indicated that the extract (75mg/kg) exhibited significant (P<0.05) analgesic effect with 62.7% inhibition when compared to the standard drug, piroxicam (10mg/kg) with 44.3% inhibition. It also inhibited the carrageenan-induced paw inflammation at the first hour (30%) compared to piroxicam (20%), although the duration of activity was better sustained with piroxicam. The median lethal dose (LD50) of the extract (i.p.) was found to be 1265mg/kg suggesting the extract to be fairly toxic. Preliminary phytochemical screening of the extract revealed the presence of alkaloids, saponins, tannins, flavonoids, steroids and terpenes. The results of this study suggest that the methanol extract of V. glaberrima contains bioactive principles which possess analgesic and anti-inflammatory activities and thus validates the use of the plant in traditional medicine for the management of pain and inflammation.