ABSTRACT
The study evaluated anticoagulant properties of the methanol extract of Newbouldia laevis leaves using blood clotting time, bleeding time and thrombin-induced clotting assay as standard procedures. Oral acute toxicity studies showed that the extract had a high safety margin, up to 2000 mg/kg in Wistar rats. The methanol leaf extract of N. laevis significantly (p<0.05) prolonged blood clotting times from the baseline value of 11.0 ± 0.6 s for the blood sample to 18.0 ± 0.7 s and 32.0 ± 1.0 s at 5 % and 10 % concentrations respectively. The crude extract also exhibited appreciable in vivo and in vitro anticoagulant potency. High doses of the extract were most significant (p<0.01) in inducing rabbit bleeding which became prolonged to 55.8 ± 1.4 s and 73.1 ± 0.8 s at 100 and 200 mg/kg respectively compared to the baseline (18.0 ± 0.2 s) and effects of the reference anticoagulants. Aspirin was found to have produced bleeding intervals of 47.0 ± 0.3 s and 70.1 ± 0.2 s at 1.0 and 2.0 mg/kg while heparin (0.75 and 1.5 mg/kg) induced bleeding times of 41.6 ± 0.8 s and 61.0 ± 1.7 s respectively. The vehicle (distilled water) induced a transient baseline bleeding time of 18.0 ± 0.2 s. However, the leaf extract of N. laevis also potentiated elevation in thrombin-induced clotting time in a dose dependent manner but at a reduced potency compared to heparin. Phytochemical analysis revealed the presence of reducing sugars, alkaloids, tannins, flavonoids, resin, phenols, proteins and acid compounds in the crude extract. The results demonstrated that the methanol leaf extract of N. laevis possesses pharmacologically active anticoagulant principles that could be isolated and evaluated for clinical or physiological purposes.
ABSTRACT
Aerial parts of Bridelia micrantha, a semi-deciduous tree are widely used in African traditional medical practice in the treatment of painful inflammatory conditions of the joints. This study evaluated the anti-inflammatory activities of the methanol leaf extract of Bridelia micrantha using acute, sub-acute and chronic models of inflammation in Wistar rats. In the carrageenan-induced acute inflammation model, 400 mg/kg of extract produced 71.79 % edema inhibition while 200 mg/kg of the extract produced 55.13 % inhibition relative to 56.41 % inhibition of the rat paw edema with 200 mg/kg of Acetylsalicylic Acid (ASA) within 5 h. In the histamineinduced rat paw edema model, the extract exhibited 72.97 % protection at 400 mg/kg compared to 83.33 % edema inhibition with phenylbutazone (100 mg/kg) after 6 h. In the sub-acute model using formaldehyde-induced paw edema, 400 mg/kg of extract showed 59.77 % (0.35±0.03) inhibition after 24 h, while 54.02 % inhibition was produced by 200 mg/kg of extract and 200 mg/kg of ASA produced 56.32 % (0.38±0.04) inhibition when compared with the negative control group (0.87±0.05). In the cotton pellet-induced granuloma test, 400 mg/kg of extract gave 52.55 % (40.57±1.3) protection, while 200 mg/kg extract gave 47.25 % protection and 200 mg/kg ASA gave 49.38 % (43.25±1.8) when compared with normal saline treated group (85.5±3.2) after 7 days. The results obtained in this study showed that Bridelia micrantha leaf extract exhibited potent anti-inflammatory activities thus authenticating its acclaimed anti-inflammatory efficacy. It was concluded that the extract of Bridelia micrantha may be a potential anti-inflammatory agent in alleviating edema associated with arthritis and musculo-skeletal pains in humans.