Gastroprotective effect of a type I arabinogalactan from soybean meal

A highly purified type I arabinogalactan (AG) from soybean meal was prepared. It contained galactose, arabinose, galacturonic acid and rhamnose in a 52:41:4:3 molar ratio and had Mw 124,000 g/mol. Methylation analysis and 13C NMR spectroscopy indicated that AG is constituted by a (1→4)-linked β-Galp main chain with substituents of α-Araf at O-3, which are in turn substituted at O-5, O-3,5, and O-2,5. It is probably linked to O-4 of some rhamnosyl units of a type I rhamnogalacturonan, formed by repeating (1→4)-α-D-GalpA-(1→2)-α-L-Rhap groups. AG significantly inhibited ethanol-induced gastric lesions in rats at an ED50 of 35 mg/kg, indicating that it has a gastroprotective effect.