Antinociceptive activity of the ethanolic extract of the root bark of Cassia sieberiana (Fam. Caesalpinaceae)

Abstract

The aqueous ethanolic extract of the root bark of C. sieberiana, a plant widely used in Ghanaian traditional medicine for pain relief of abdominal origin, dysmenorrhea, ulcers and general body pains, was investigated for antinociceptive effect in a thermal model for pain and anti-colitic actions in rats. Algesia in the form of thermal stimuli was induced using the hotplate model and colitis by intra-colonic instillation of 2, 4, 6-tri-nitrobenzene sulphonic acid (TNBS). Both morphine (1 - 5 mg/kg, i.p.) and C. sieberiana extract (10 - 40 mg/kg, p.o.) caused dose dependent anti-nociceptive effects in rats on the hotplate. The mean maximal analgesic effects occurred 30 minutes after administration of either morphine (1 - 5 mg/kg, i.p.) or extract. There was no statistical difference between the analgesic potency of the extract (EC50: 9.7±3.9) and that of morphine (EC50: 6.5±0.5). However, the analgesic action of C. sieberiana (40 mg/kg, p.o.) was less sensitive than that of morphine to the effect of naloxone (0.5 mg/kg, i.p.) which caused 14.7% and 75.3% reductions of the effects of C. sieberiana and morphine respectively. In rats with TNBS-induced colitis, whereas treatment with both Prednisolone (10 mg kg-1 p.o.) and 5-Aminosalicylic acid (5-ASA) (100 mgkg-1 i.r.) significantly reduced the inflammatory features of the damaged colons, the extract (160 mg kg-1 p.o.) effect was less obvious. We conclude that the aqueous ethanolic extract of C. sieberiana possesses potential analgesic compounds but lacks compounds with promise for anticolitic actions