Evaluation of the Stem Bark Extract Picralima nitida for Antinociceptive Property

Aims: To investigate the antinociceptive property of Picralima nitida stem bark methanol extract. Place and duration of study: Department of Veterinary Physiology and Pharmacology, Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria from February to July, 2020.

Methodology: The extraction was done by cold maceration of the pulverised P. nitida stem bark in 80% methanol for 48 hours. Acute toxicity study was done using up and down method. The antinociceptive study was carried out using tail flick and hot plate antinociceptive models. The extract was used at the doses of 100, 200 and 400 mg/kg while pentazocine 3 mg/kg was used as the standard reference drug (positive group) and 5 ml/kg distilled water was used for the negative group.

Results: In the tail flick test, P. nitida at the doses of 100 and 400 mg/kg with the standard drug pentazocine significantly (P = 0.05) increased the pain reaction time (PRT), increasing the PRT from 1.80 ± 0.08 sec in the negative group (distilled water 5 ml/kg) to 2.90 ± 0.18 sec at the dose of 200 mg/kg group of mice representing 62.06% increase. Also, in the hot plate model, the PRT was increased from 2.03 ± 0.02 sec in distilled water treated group of mice to 9.58 ± 0.99 sec in the 400 mg/kg dose of the extract.

Conclusion: The stem bark methanol extract of P. nitida demonstrated a good level of antinociceptive activity in the models used in this study.