Background: Terminalia avicennioides is a medicinal plant used traditionally in Nigeria to treat numerous ailments and disorders which include coughs, purgative and emetic. Objective: This study scientifically evaluated the probable mechanism of the anti-emetic activity of methanol root extract of Terminalia avicennioides Guill. & Perr. on histaminergic and serotonergic receptors of isolated rabbit ileum. Methodology: Fresh root bark was extracted using methanol and the antiemetic effect was evaluated by experimenting on a small segment (3 cm) of isolated rabbit ileum, using the data capsule (Ugo Basile) and single chamber isolated tissue apparatus. Varying concentrations of histamine and serotonin (0.05, 0.1, 0.2, and 0.4 mg/ml) were used to obtain contractions as they act on histamine and serotonergic receptors respectively. Results: META (0.05 mg/ml, 0.1 mg/ml, 0.2 mg/ml, and 0.4 mg/ml) exhibited a significant concentration-dependent decrease at p<0.05 in histamine-induced and serotonin-induced contractions on isolated rabbit ileum from the data capsule reading with percentage inhibition of 43.22, 53.96, 75.35, 85.58 % and 21.62, 49.50, 78.67 and 86.96 % respectively for the different concentrations. Conclusion: The study showed that methanol root extract of Terminalia avicennioides acts on cholinergic (muscarinic), histaminergic, and serotonergic receptors of isolated rabbit ileum by inhibitory spasmolytic action against smooth muscle contractility, hence its ability to possess anti-emetic effect to relieve vomiting.

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Background: Peptic ulcer affects up to 10 % of the world’s population. There has been renewed interest in identifying natural drug sources with gastroprotective activity. Unripe Carica papaya fruit is used traditionally for the treatment of various gastrointestinal disorders including peptic ulcer which may have not been well explored. Objective: The aim of this study was to determine the gastroprotective activity of methanol extract of mesocarp of unripe Carica papaya fruit (MECP) on experimentally-induced gastric ulcer in Wistar rats. Methodology: Forty-six (46) wistar rats (150 g to 170 g) were used for the studies. Six (6) were used for acute toxicity testing using OECD method no.423. Graded doses of MECP (500, 1000 and 1500 mg/kg) were administered as gastroprotective agents, omeprazole and cimetidine were standard drugs used for ethanol-induced and acetic acid-induced ulcer models respectively. Thereafter, 20 rats each were used for ethanol-induced and acetic acid-induced ulcer models to induce gastric ulcers. All drugs and extracts administration were via oral route. Subsequently, animals were euthanized; stomachs excised, cut open and measured to examine the extent of ulceration and level of protection by the MECP. Results: Phytochemical screening showed MECP contains alkaloids, flavonoids, saponins, glycosides, tannins and terpenoids. Anthraquinones were absent. Results of acute toxicity test indicated that MECP is relatively safe with LD50 > 5000 mg/kg. In ethanol-induced ulcer model, rats administered with 1000 mg/kg MECP had the least mean ulcer index (0.917 cm2 ± 0.086) with the highest ulcer protection percentage (76.95 %) of all the extract doses, relative to the standard (omeprazole) with 77.93 % protection. Reduction in mean ulcer index was recorded across the MECP groups for analysis of variance, using Dunnetts post-hoc test for multiple comparison, but showed no statistically significant difference between them. For acetic acid-induced ulcer model, MECP at the lowest dose (500 mg/kg) elicited the least mean ulcer index (0.678 cm2± 0.102) with 87.54 % ulcer protection in a similar manner to cimetidine (20 mg/kg) which had 0.600 cm2 + 0.144 mean ulcer index with 88.97 % ulcer protection. All doses of MECP showed reduction in mean ulcer index when compared to (5.442 cm2 ± 0.511) of the untreated group (normal saline) with no statistically significant difference recorded. Conclusion: MECP has gastroprotective and ulcer healing effects on ethanol-induced ulcer and acetic acid-induced ulcer in Wistar rats. This confirms scientifically, the traditional use of mesocarp of unripe Carica papaya fruit in treatment of peptic ulcer