ABSTRACT

The anti-inflammatory and tonic properties of methanol extract of Arachis hypogea leaves were studied in vitro and in vivo. Qualitative phytochemical screening revealed the presence of alkaloids, glycosides, fats and oils, phenols and lignins. Acute toxicity test showed that the extract was not toxic up to 500mg/kg body weight. There was a non-significant difference (p>0.05) in the rat paw oedema induced by egg-albumin for 1hr in group administered 10mg/kg b.w of aspirin (group 2) and those administered 200mg/kg and 400mg/kg of methanol extract of Arachis hypogea leaves (groups 3 and 4) respectively, when compared with the control (group 1) rats that were administered 5ml/kg b.w normal saline. However, there was a significant decrease (p<0.05) in the paw width of the rats after induction for 2,3,4,5 and 6hrs in groups 2, 3 and 4 when compared with group 1. In vitro study showed a significant (p<0.05) dose-dependent inhibition of platelet aggregation by the extract at the tested concentrations. Also, the extract significantly (p<0.05) decreased the hemoglobin concentrations in groups 3 and 4 when compared with groups 1 and 2. Tonicity studies using rabbit jejunum showed a significant (p<0.05) relaxation effect on that smooth muscle. At 14.28µg/ml, 29µg/ml and 57.14µg/ml, the extract inhibited in vitro acetylcholine-induced contraction of the rabbit jejunum by 84.21%, 86.84% and 89.47% respectively, which compared closely with the effect of atropine (90.21% at 0.28µg/ml). In conclusion, the results of this study strongly indicated that the methanol extract of Arachis hypogea leaves possesses anti-inflammatory and smooth muscle relaxant properties, suggesting that it contains substances with potent parasympatholytic and anti-inflammatory properties by relieving oedema and inhibiting platelet aggregation, prostaglandin synthase activity and reducing erythrocyte osmotic fragility.