Gastroprotective Activity Of Methanol Extract Of Mesocarp Of Unripe Carica Papaya Linn. Fruit On Experimentally-induced Gastric Ulcer In Wistar Rats

Abstract

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