Polysaccharides from prunes: Gastroprotective activity and structural elucidation of bioactive pectins

Prunes are the dried fruits from Prunus domestica. After the purification steps, two homogeneous polysaccharides were characterised, SF-50R and SF-50E and contained Ara:Gal:Rha:GalA in 47.8:31.5:10.7:10.0 and 39.6:50.3:5.1:5.0 molar ratios, respectively. Methylation analysis and 13C NMR spectroscopy indicated that both fractions are constituted by rhamnogalacturonans with type I arabinogalactans as side chains, differing mainly in the proportions of the rhamnogalacturonan backbone, in the length of the (1 → 4)-β-galactan chain and in the proportion of the arabinan side chain. Crude water extract (PWH) and fraction SF-50E were evaluated for their gastroprotective properties against ethanol-induced acute gastric lesions in rats. Oral administration of PWH (3 and 10 mg/kg) reduced the gastric lesion area by 67 ± 11% and 60 ± 12%, respectively, while fraction SF-50E (10 and 30 mg/kg) inhibited the lesion area by 84 ± 12% and 83 ± 12%, respectively. These results indicated that prune's polysaccharides act as gastroprotective agents in rats.