Anti-nociceptive activity of methanolic extract of ocimum gratissimum (labiate) on experimental animals

Abstract

The methanolic leaves extract of Ocimum gratissimum was investigated for anti-nociceptive effects in mice. The models used to study the effect on nociception are the acetic acid induced abdominal constriction test, hot- plate method in mice. The extract demonstrated a significant (P< 0.05) anti-nociceptive activity at all the doses (50,100 and 200 mg/kg body weight i.p.) tested group and standard group (piroxicam 20mg/kg) compared to control normal saline. The activity resides more at the highest dose 200mg/kg body weight i.p. that was found to have the highest percentage (92.5 %) of inhibition of the abdominal constriction induced by acetic acid in mice. Also the extract was found to have a significant (p <0.05) inhibitory effect on hot-plate method at all the three doses. The extract caused a significant (p<0.05), dose dependent inhibition of acetic acid-induced writhing and hot-plate method. The intraperitoneal LD50 value of the extract was 1285.5mg/kg body weight in mice. Preliminary phytochemical screening revealed the presence of alkaloids, saponins, tannins and flavonoids. The results suggest the extract contained pharmacologically active principles, and supports the local application of the plant in painful conditions. Further studies may reveal the exact mechanisms of action responsible for the analgesic activities of O. gratissimum leaves extract.