Gastroprotective effect and structure of a rhamnogalacturonan from Acmella oleracea

► A methyl esterified rhamnogalacturonan was isolated and characterized from Acmella oleracea. ► The rhamnogalacturonan is partially substituted by side-chains of type II arabinogalactans. ► The polysaccharide reduced ethanol-induced gastric lesions in rats with an ED50 of 1.5 mg/kg. ► Rhamnogalacturonan of A. oleracea may be a gastroprotective agent.