Objective: To investigate the antinociceptive and anti-inflammatory potentials of the leaf extract and fractions of Lupinus arboreus in rodents. Methods: The methanol extract (ME) and fractions of Lupinus arboreus leaf were studied using acetic acid-induced (writhing reflex) pain, pressure-induced (rat tail immersion) pain, thermally-induced (hot plate) pain as well as formaldehyde- and egg albumin-induced rat paw oedema for antinociceptive and anti-inflammatory studies respectively. Acute toxicity and lethality (LD50) test and phytochemical analysis were also carried out. Results: The extract (30 and 60 mg/kg i.p) exhibited a dose-related significant (p<0.05) antinociceptive activity in mice. At 60mg/kg, Hexane fraction (HEF) and Ethylacetate fraction (EAF) exhibited significant (p<0.05) pain inhibition of 73 and 64 % respectively, while methanol extract fraction (MEF) produced non significant (p>0.05) 24 % pain inhibition. In both albumin (acute) and formaldehyde (chronic) induced oedema in rats, the extract (30, 60 mg/kg i.p) produced a significant (p<0.05) dose-related inhibition. Similarly, HEF and EAF at 60 mg/kg produced a significant (p<0.05) oedema inhibition. The MEF (60 mg/kg) showed no significant (p>0.05) effect. The intraperitoneal acute toxicity test revealed LD50 of 77.4mg/kg, while the phytochemical studies showed the presence of steroids, terpenes, flavonoids, glycosides, saponins, alkaloids, tannins, resins, protein and reducing sugar. Conclusion: The results demonstrated that the leaves of L. arboreus possess antinociceptive and anti inflammatory effects in rodents.
