Gastroprotective Effects of β-sitosterol and β-sitosterol-3-O-β-D-glucopyranoside from Bridelia ferruginea Stem Bark

The methanol extract of Bridelia ferruginea Benth. (Euphorbiaceae) stem bark (BFME) was partitioned in chloroform-methanol-water (2:2:1) mixture to obtain the Chloroform (CF) and Aqueous Methanol (AMF) fractions. The BFME, CF and AMF were screened for antiulcer activity using indomethacin-induced ulcer as activity guide. The CF provided the highest gastroprotection and was subsequently fractionated in a silica gel (60-200 mesh) column eluted with different mixtures of n-hexane and ethyl acetate (100:0; 95:5; 90:10; 80:20) to obtain six fractions (I-VI). Fractions III and VI offered the highest protection against indomethacin-induced ulcer and were further purified in a sephadex LH-20 column eluted with methanol to yield two compounds, BF1 and BF2. Using Nuclear Magnetic Resonance (¹H-NMR, ¹³C-NMR) and electron impact mass spectroscopies, BF1 and BF2 were confirmed to be β-sitosterol and β-sitosterol-3-O-βD glucopyranoside respectively. The BFME, fractions, β-sitosterol and β-sitosterol-3-O-β-D-glucopyranoside elicited dose-related and significant (P<0.05) protection against various ulcers in rats. β-sitosterol, 100 and 300 mg/kg, produced 79.70, 82.18, 42.31, 44.87, 65.97, 70.83, 80.22 and 87.91% gastroprotection; while β-sitosterol-3-O-β-D-glucopyranoside, 100 and 300 mg/kg, caused 69.80 and 74.26, 33.33, 35.26, 84.03, 95.83, 83.52 and 85.71% gastroprotection against indomethacin-, ethanol-, cold restraint stress- and pylorus ligation- induced ulcers, respectively. Results demonstrated gastroprotective effects of B. ferruginea stem bark, attributable to β-sitosterol and β-sitosterol-3-O-β-D-glucopyranoside.