Cletus Anes Ukwubile - Department of Pharmacognosy, Faculty of Pharmacy, University of Maiduguri, Maiduguri, Nigeria.
Troy Salvia Malgwi - Department of Pharmacognosy, Faculty of Pharmacy, University of Maiduguri, Maiduguri, Nigeria.
Nnamdi David Menkiti - Department of Chemistry, Faculty of Science, Ahmadu Bello University, Zaria, Nigeria.

Background: Strychnos spinosa is a tree whose parts are popularly used in Southeast Nigeria to treat pains, infections, inflammations, hypertension, malaria fever, and ulcers. This study isolates the bioactive compounds in methanol stembark extract and evaluates the antinociceptive and anti-inflammatory potentials of S. spinosa.  Methods: Bioactive compounds were isolated using silica gel column chromatography, and their structures were elucidated using Fourier-transform infrared spectroscopy, gas chromatography/mass spectrometry, liquid chromatography/mass spectrometry, and nuclear magnetic resonance spectroscopy apparatus. The antinociceptive activity was determined using the acetic acid-induced writhing mice model, hot plate method, and tail immersion. In contrast, the anti-inflammatory activity was assessed using carrageenan-induced paw-edema in mice.  Results: The structural elucidation of the major bioactive compounds showed that the compounds are ۱۸-methylnonadecanoate ester, ۲-pyridin-۳yl-ethanimidamide, ۲-ethylformanilide, and acetamide. The extract at the doses of ۲۰۰, ۴۰۰, and ۸۰۰ mg/kg, intraperitoneal significantly decreased (P<۰.۰۵) pains in acetic acid-induced writhing in mice, hot plate, and tail immersion assays in a dose-dependent fashion. In the hot plate and tail immersion assays, the extract produced significant pain inhibition of >۵۰% after ۱۲۰ min at a ۴۰۰ mg/kg dose. In contrast, the stembark extract of S. spinosa produced the highest inhibition of paw edema formation at a dose of ۴۰۰ mg/kg in ۶ h in the carrageenan-induced paw edema model.  Conclusion: The results affirmed using S. spinosa stembark extract in traditional medicine to treat pain and inflammation. This was possible due to the presence of the isolated compounds.

Bioactive compounds, Column chromatography, Strychnos spinosa, Antinociceptive, Anti-inflammatory