Analgesic and Anti-inflammatory Activities of the Residual Aqueous Fraction of Carissa edulis Root Bark (Vahl) in Experimental Animals

Background: Carissa edulis is a spiny evergreen shrub that may reach a height of 5 feet and an equal breadth. The bark is grey and smooth with straight woody double-pronged spine often in pairs. The plant is a native of South Africa. It grows in tropical African region and Arabia. It has been used in the traditional treatment of malaria, headache, glandular inflammation, rheumatism and chest complaints among others for many years and their efficacy is widely acclaimed among the Hausa communities of northern Nigeria. Hence, there need for verification of these folkloric claims. Objectives: The current study aimed at evaluating the analgesic and anti-inflammatory activities of the residual aqueous fraction of the ethanol root bark extract of C edulis in mice and rat models. Methodology: Acetic acid-induced writhing and tail immersion test in mice were used to assess analgesic properties, while anti-inflammatory effect was tested using carrageenan-induced paw oedema in rats. Results: The fraction (150, 300 and 600 mg/kg) and standard drugs significantly (p<0.05) reduced the number of writhes and prolonged the pain reaction time, in acetic acid-induced writhing and tail immersion models respectively. Similarly, the fraction (300 and 600 mg/kg) and ketoprofen (10 mg/kg) exhibited significant (p<0.05) decrease in the paw oedema at 1, 2, 3 and 4 hour intervals, while at 150 mg/kg, the decrease was significant at only third hour. Discussion: The study has shown that the residual aqueous fraction of C. edulis possesses analgesic and anti-inflammatory activity, thus, justified the traditional use of the plant in pain and inflammatory conditions. Keywords: Carissa edulis, writhes, inflammation, analgesic, fractio