Analgesic, antipyretic and anti-inflammatory properties of Mezoneuron benthamianum Baill (Caesalpiniaceae).

The analgesic, antipyretic and anti-inflammatory effects of the aqueous extract of Mezoneuron benthamianum (MB) were evaluated in mice, rats and rabbits using the mouse writhing, tail flick, hot plate and formalin-induced pain tests; 2-4-Dinitrophenol (DNP), D-Amphetamine and E-coli Lipopolysaccharide-induced pyrexia and carrageenan, egg albumin and xylene-induced oedema. The extract (400-1600 mg/kg) and acetylsalicylic acid (100 mg/ kg) produced a significant (P < 0.05) inhibition of the second phase response in the formalin pain model, while only the highest dose (1600 mg/kg) of the extract showed a comparable antinociceptive effect in the first phase. The extract also showed a dose-dependent inhibition of acetic acid induced abdominal writhing. The tail flick latency and the hot plate pain threshold were dose dependently enhanced by the extract but these were significantly lower than that produced by morphine (2 mg/kg). The 2,4-DNP and D-Amphetamine (10 and 5 mg/kg, i.p.respectively) increased the rectal temperatures of rats within 30 minutes of their administration. The extract at doses of 400,800 and 1600 mg/kg produced significant lowering of the elevated body temperature in rats. The extract (800 mg/ kg) administered orally to rabbits passaged with E. coil lipopolysacharride was able to relieve the pyrogen induced fever. The antipyretic effect produced by the extract was comparable to a standard antipyretic drug, aspirin. The extract (400-1600 mg/kg) administered 1h after carrageenan-induced paw swelling did not inhibit the oedema. No inhibitions were observed with the egg albumin and xylene induced oedema models. Phytochemical analysis revealed the presence of flavonoids, tannins, cardiac glycosides, anthraquinones, and saponins. Administration of the extract up to 2 g/kg (orally) did not produce any toxic effect in the acute toxicity studies in mice. The LD50 of the extract when administered intraperitoneally was 1021.31 mg/kg. The data obtained show that MB extract possesses analgesic and antipyretic activities but lacks an anti-inflammatory property.