Propriétés analgésiques et non-ulcérogéniques de l’extrait aqueux des écorces du tronc de Morinda Lucida (Rubiaceae) chez la souris

Abstract

Morinda lucida (root, leaves and bark stem) is a plant widely used in traditional medicine in Africa, particularly in Cameroon for the treatment of dysmenorrhea, gastric ulcer, rheumatic and throat pains (inflammation of tonsil). The aim of this study was evaluated the analgesic and ulcerogenis effects of the aqueous extract of the stem bark Morinda lucida in mice. The effects of the aqueous extract of the stem bark of Morinda lucida were tested on models of acute pain induced by acetic acid (0.6%) and formalin (2.5%) in mouse fasted since 12 hours. The ulcerogenic effect of this plant was evaluated by administration of different doses of the aqueous extract to mouse fasted since 48 hours. For each test, 30 mouse was used and divided into 5 groups of 6 animals (3 males and 3 females): one negative control group receiving distilled water; one positive control receiving indomethacin (50 mg/kg); 3 experimental groups receiving the aqueous extract at doses of 100; 200 and 400 mg/kg. The oral administration of aqueous extract of Morinda lucida significantly (***p<0.001) dose dependently reduced the number of abdominal constrictions induced by injection of acetic acid. A maximum inhibition of 80.20% was obtained at the dose of 400 mg/kg. Also, this extract significantly and dose dependently inhibited both phases (*p<0.05; ***p<0.001) of pain induced by formalin injection; the first phase was reduced up to 53.7% while the second phase was reduced up to 75.88%. The oral administration of the aqueous extract of this plant doesn’t caused gastric ulcer. On the contrary, it significantly (*p<0.05; **p<0.01) and dose dependently stimulated the mucus secretion. In sum, the aqueous extract of stem bark of Morinda ludica possesses analgesic (central and peripheral) and non-ulcerogenic properties.