Prune protection: NMR looks at pectins

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  • Published: Nov 15, 2013
  • Author: David Bradley
  • Channels: NMR Knowledge Base
thumbnail image: Prune protection: NMR looks at pectins

Spectroscopic prunes

Prune, photo by David Bradley. Prunes, the dried carcass of the plum are infamous for their interaction with the gastrointestinal tract. Now, carbon-13 NMR spectroscopy has been used in studies of gastroprotective compounds, pectins, found in prunes. The compounds are rhamnogalacturonans with type I arabinogalactans as side chains and insights into their structures and physiological effects could offer new insights into the biochemistry of the gut.

Prunes, the dried carcass of the plum are infamous for their interaction with the gastrointestinal tract. Now, carbon-13 NMR spectroscopy has been used in studies of gastroprotective compounds, pectins, found in prunes. The compounds are rhamnogalacturonans with type I arabinogalactans as side chains and insights into their structures and physiological effects could offer new insights into understanding gastric protection.

Thaisa Moro Cantu-Jungles, Daniele Maria-Ferreira, Luisa Mota da Silva, Cristiane Hatsuko Baggio, Maria Fernanda de Paula Werner, Marcello Iacomini, Thales Cipriani and Lucimara Cordeiro of the Federal University of Paraná, Brazil, explain how the dried fruit of Prunus domestica are big business, particularly in California, USA, which produces around 120,000 tonnes annually, representing 70% of the world supply. Prunes are often consumed directly, in syrup, as their juice or in various cuisines, particularly those of North Africa, the Middle East and surrounding regions. They have also been developed into products that can be used as a substitute for animal fat or vegetable oils in baking.

Alimentary, my dear

Prunes are commonly used as a folk remedy for constipation and there is some limited evidence of efficacy in treating osteoporosis, high blood pressure and dyslipidaemia. Prunes have also been linked to a reduction in plasma and liver fats. Carbohydrates represent almost two-thirds of the weight of prunes. But, until now the presence of only one compound has been discussed in the scientific literature, xyloglucan. The Brazilian team has thus reported the isolation, composition, and structural features of two rhamnogalacturonans with type I arabinogalactan side chains from prunes. They have also investigated the anti-ulcer activity of both crude and purified fractions.

The team carried out purification of prune extract from pitted fruit and characterised two homogeneous polysaccharides, SF-50R and SF-50E, which contain the sequence Ara:Gal:Rha:GalA in two distinct molar ratios (47.8:31.5:10.7:10.0 and 39.6:50.3:5.1:5.0, respectively). They carried out methylation analysis and carbon-13 NMR spectroscopy, which they explain indicates that both fractions are constituted by the rhamnogalacturonans described above.

Anti-ulcer activity

Crude water extract of prune and SF-50E were both tested for their gastroprotective properties in acute, ethanol-induced gastric lesions in female, laboratory (Wistar) rats, the team reports. Oral administration of crude extract at 3 and 10 milligrams per kilogram reduced gastric lesion area by 67 ± 11% and 60 ± 12%, respectively, However, the SF-50E at 10 and 30 mg/kg shrank the lesion area by 84 ± 12% and 83 ± 12%, respectively. Thus, the team suggests that it is the presence of the polysaccharides in prunes that offer a gastroprotective effect against stomach ulcer, in rats at least.

"Regarding the next step, our research group are planning to purify and test other polysaccharides from prunes and also from other tropical and exotic fruits," Cordeiro told SpectroscopyNOW.

Related Links

Food Chem 2014, 146, 492-499: "Polysaccharides from prunes: Gastroprotective activity and structural elucidation of bioactive pectins"

Article by David Bradley

The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

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