Anti-diarrhoeal activity of the aqueous extract of Mezoneuron benthamianum Baill (Caesalpiniaceae)

The effect of the aqueous extract of Mezoneuron benthamianum (MB) on experimentally induced diarrhoea, intestinal propulsive movement (IPM) and intestinal fluid accumulation (enteropooling) were investigated in rats and mice. The extract (400, 800 and 1600 mg/kg, orally) produced a significant (p<0.05) and dose-dependent reduction in propulsion in the castor oil-induced intestinal transit in mice. The mean peristaltic index (%) for these doses of extract, control, (distilled water, 10 ml/kg, p.o.) and morphine, (10 mg/kg, s.c.) were 73.48, 69.34, 57.27, 89.93 and 31.56, respectively. The effect of the extract at the highest dose was significantly (p<0.05) lower than that of the standard drug. This effect was antagonised by yohimbine (1mg/kg, s.c.). In a dose-dependent manner, the extract delayed the onset of diarrhoea, produced a significant decrease in the frequency of defaecation, severity of diarrhoea and protected the mice treated with castor oil. Total diarrhoea scores were 12.0+/-0.63, 10.3+/-2.06, 8.5+/-2.15, 7.1+/-0.91 and 5.8+/-0.79 for control, extract (400, 800 and 1600 mg/kg) and morphine, respectively. The extract significantly decreased the volume (ml) of intestinal fluid secretion induced by castor oil (1.75+/-0.02 to 0.93+/-0.04) compared with 1.90+/-0.05 for control. The inhibitory effect on fluid accumulation by the extract was also attenuated by yohimbine (1.0 mg/kg). Preliminary phytochemical screening 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 LD(50) of the extract when given intraperitoneally was 1021.31 mg/kg. The results obtained show that MB possesses anti-diarrhoeal activity due to its inhibitory effects on gastrointestinal propulsion and intestinal fluid accumulation. The antagonistic actions of yohimbine in the experiments suggest a role for the a(2)-adrenergic receptor system.

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.

Evaluation of antiplasmodial activity of ethanolic seed extract of Picralima nitida

The in vivo antiplasmodial activity of the ethanol seed extract of Picralima nitida grown particularly for the leaf and seed in Niger Delta region of Nigeria was evaluated in Plasmodium berghei berghei infected mice. Picralima nitida (35-115 mg/kg day) exhibited significant (P<0.05) blood schizonticidal activity both in 4-day early infection test and in established infection with a considerable mean survival time though not comparable to that of the standard drug, chloroquine, 5 mg/kg day. The seed extract possesses significant (P<0.05) antiplasmodial activity which correlate with it reported in vitro activity.