Abstract

ANTI-INFLAMMATORY AND ANTINOCICEPTIVE EFFECTS OF THE STEM BARK AQUEOUS EXTRACT OF RAUWOLFIA VOMITORIA (APOCYNACEAE)

Youmbie Djanche Duplex Bonheur, Dzeufiet Djomeni Paul Désiré, Nkwengoua Ernestine, Mezui Christophe, Dimo Théophile*.

ABSTRACT

Rauwolfia vomitoria (Apocynaceae) has been used traditionally in Cameroon and other countries as remedy against gastritis, chest pain, epilepsy, carious teeth, rheumatic pain, headache and inflammation. This study was aimed to investigate the anti-inflammatory and antinociceptive activities of the stem bark aqueous extract of Rauwolfia vomitoria which is empirically used in Cameroon to treat rheumatic pain, so as to justify its traditional use in the above mentioned pathological conditions. Anti-inflammatory activity test was done on female wistar rats at three differents doses (100, 200 and 300 mg/kg body weight) by using carrageenan, serotonin, histamine, dextran and formalin paw edema tests. The antinociceptive activity test was performed employing tail immersion test on rats, hot plate method, acetic acid induced writhing test, and formalin-induced pain test on swiss albino mice on both sexes at the doses of 100, 200 and 300 mg/kg body weight. The extract significantly reduced the oedema induced by carrageenan within 30 min with 300 mg/kg body weight being the most potent. The extract at the same dose also significantly inhibited the oedema induced by serotonin, histamine, dextran and formalin with the maximum percentage of inhibition of 36.89, 32.75, 39.67 and 38.35% respectively. The extract significantly reduced the number of writhing with the percentage of inhibition of 56.63 % at the dose of 300 mg/kg. In the hot plate and tail immersion tests, aqueous extract increased significantly the latency reaction time from 11.58 s to 16.62 s (44.27%) and from 8.31 s to 12.41 s (48.31%) respectively at the dose of 300 mg/kg. It also significantly inhibited pain and inflammation induced by formalin in neurogenic (37.64%) and inflammatory (46.44%) phases at the dose of 300 mg/kg. Qualitative phytochemical screening revealed presence of alkaloids and flavonoids, which are involved in anti-inflammatory and antinociceptive activities. The results indicated that aqueous extract might have central and peripheral analgesic properties as well as anti-inflammatory activities.

Keywords: Rauwolfia vomitoria; anti-inflammatory activity; antinociceptive activity; inflammation; pain.