ABSTRACT
Aim: Phyllanthus amarus Schum (Euphorbiaceae) is an annual herbal shrub which has been used in traditional medicine in Nigeria to treat some disease conditions. The aim of this study is to evaluate the anti-inflammatory and analgesic activities of the aqueous extract of Phyllanthus amarus in experimental animal models hence confirming its folkloric use. Study Design: Forty healthy white Wister strain albino rats (100–200g) and forty mice (15–30g) of either sex bred in the experimental animal house of the Faculty of Veterinary Medicine, University of Ibadan, Nigeria were used for the study. Forty rats were used for anti-inflammatory study while forty mice used for the analgesic study. In anti-inflammatory study, carrageenan and histamine-induced paw oedema were used while acetic acidinduced writhing test and formalin-induced paw lick test were deployed for analgesic test. Place and Duration of Study: Faculty of Veterinary Medicine, University of Ibadan, Nigeria; 2 months. Methodology: Soft drink extract (SDE) was prepared by dissolving ground plant materials (200g) in 1 L seven up (7 UP®) for 48 h, filtered, lyophilized and then used for the pharmacological investigations. Standard phytochemical methods were used to test for the presence of phytoactive compounds in the plant. Acute toxicity was carried out in mice to determine safe doses for use. The anti-inflammatory activities were conducted using carrageenan and histamine to induce oedema in rats while analgesic activities were embarked upon using acetic acid- induced writhing test and formalin-induced paw lick test. Results: The extract in doses of 100 and 200 mg/kg at 3 hr showed 15.1 and 16.4% inhibition of histamine induced-paw oedema respectively while ibuprofen caused 9.6% inhibition at the same period. In the case of carrageenan induced paw oedema, the extract in doses of 100 and 200 mg/kg at 4 hr showed 10.5 and 12.0% inhibition respectively while ibuprofen only caused 3% inhibition. In the acetic acid- induced writhing test, the extract showed a good analgesic activity characterized by a significant reduction in the number of writhes with 100 and 200 mg/kg doses used when compared to the control group. The result was also similar to the formalin-induced paw lick test. Conclusion: The soft drink leaf extract of Phyllanthus amarus has both analgesic and anti-inflammatory potential. The activities of this extract were comparable to that of ibuprofen, the reference drug used in this study.