Isolation, Structural Elucidation and Gastroprotective Activity of Triterpenoids from Ficus exasperata Bark in Experimentally Induced Gastric Ulcer Models

Ficus exasperata, known as sandpaper leaf tree, is used in traditional medicine across the North Central and South West zones of Nigeria for the management of gastric ulcers, abdominal pain, and gastrointestinal disorders. Previous studies have indicated promising biological activity, but isolation and characterisation of the specific gastroprotective constituents from Nigerian samples have not been systematically reported. This study isolated and structurally elucidated triterpenoid compounds from methanol bark extract of F. exasperata collected from Niger State, and evaluated their gastroprotective activity in experimental rat models. Column chromatography over silica gel yielded three triterpenoid fractions, and structure elucidation was performed by spectroscopic methods including 1H-NMR, 13C-NMR, and HRMS. Gastroprotective activity was assessed in ethanol-induced and indomethacin-induced gastric ulcer models in Wistar rats. Ulcer index, mucus secretion, and gastric acid secretion were measured as outcome parameters. Two isolated ursane-type triterpenoids, identified as ursolic acid and beta-amyrin, demonstrated significant gastroprotection at 50 mg/kg, reducing ulcer index by 67 and 58% respectively. Mucus secretion was significantly enhanced while gastric acid output was reduced compared to ulcer control groups. Omeprazole at 20 mg/kg reduced ulcer index by 74% under the same conditions. These results confirm the gastroprotective activity of F. exasperata bark triterpenoids and support their further development as candidate leads for antiulcer drug discovery. Keywords: Ficus exasperata, triterpenoids, gastroprotective, gastric ulcer, Niger State.