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

doi:10.1016/j.foodchem.2013.09.093

Food Chemistry

Volume 146, 1 March 2014, Pages 492-499

https://doi.org/10.1016/j.foodchem.2013.09.093 Get rights and content

Highlights

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Pectic polysaccharides from prunes were extracted, purified and characterised.
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Two purified fractions, SF-50E and SF-50R, were obtained.
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Fractions were constituted by rhamnogalacturonans with type I arabinogalactans.
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Crude water extract and SF-50E were tested for their gastroprotective properties.
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Tested polysaccharides acted as a gastroprotective agents in rats.

Abstract

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.

Introduction

Prunes are the dried fruits from Prunus domestica L. which is originated from the Caucasus regions, bordering the Caspian Sea (Stacewicz-Sapuntzakis, Bowen, Hussain, Damayanti-Wood, & Farnsworth, 2011). This specie belongs to the genus Prunus (Rosaceae family), that comprises other plants that also produce edible fruits such as peach (Prunus persica), cherries (Prunus cerasus and Prunus avium) and apricot (Prunus insitia) (Stephen, 1983).

Prunes have a large economic impact especially in California, which is responsible for an average of 70% of the world’s prune supply, and was estimated to produce 120,000 tons of prunes in 2012 (Perez & Pollack, 2012). Thought the main usage of prunes is for direct consumption, there are several other applications for it in the culinary and industry, such as in the production of prune juice, prune puree, mixtures with cereal or even ground meat, and for the development of products that replace fat in baking (Stacewicz-Sapuntzakis et al., 2011).

Prunes are also used as a remedy for various diseases. Recent studies also showed clinical evidence of its activity in the treatment of constipation, osteoporosis, hypertension and dyslipidemia (Stacewicz-Sapuntzakis et al., 2011). It was also shown that fibres from prunes lowered plasma and liver lipids (Tinker, Davis, & Schneeman, 1994) and probably were the most important components responsible for satiety promoted by prunes consumption (Farajian, Katsagani, & Zampelas, 2010).

Carbohydrates are the main macronutrient in prunes, and consist 62.7% of their total weight (Stacewicz-Sapuntzakis et al., 2011). Despite this high content and their importance for some biological functions attributed to prunes, up to now, only the presence of a xyloglucan was reported in prunes (Ito & Kato, 2002). Thus, this paper reports the isolation, composition, and structural features of two rhamnogalacturonans with type I arabinogalactan side chains from prunes, as well as the anti-ulcer activity of both crude and a purified fractions. To our knowledge, neither the structure of these pectic polysaccharides isolated from prunes nor their gastroprotective activity has been reported yet.

Section snippets

Plant material

Pitted prunes (P. domestica) from cultivar d’Agen were purchased in a local market in Curitiba/PR (LA VIOLETERA®).

General analytical methods

Fractions were carboxy-reduced by the carbodiimide method (Taylor & Conrad, 1972) using NaBH₄ as the reducing agent, giving products with the –COOH groups of its uronic acid residues reduced to –CH₂OH.

The degree of acetylation (DA) was determined after spectrophotometric quantification of acetyl following the method of Hestrin (1949), employing galactose pentaacetate as a standard.

Extraction and purification of polysaccharides

Results and discussion

Polysaccharides were extracted from prunes with cold and hot water, giving fractions PWC (0.5% yield) and PWH (8.1% yield), respectively. Monosaccharide analysis of these fractions indicated Ara:Gal:Glc as neutral sugars in the 16:15:3 and 23:21:2 molar ratios, respectively. The content of uronic acids was determined spectrophotometrically and showed values of 66% and 54%, respectively.

A freeze-thaw treatment was applied in fractions PWC and PWH, however, no cold-water insoluble polysaccharides

Acknowledgements

This research was supported by Projeto Universal (Process 475747/2010-0) provided by CNPq foundation (Brazil) and by PRONEX-Carboidratos. C.H. Baggio is recipient of post-doctoral scholarship from the CNPq. The authors are grateful to Dr. Guilherme L. Sassaki and Arquimedes Santana-Filho for recording the NMR spectra.

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

Highlights

Abstract

Introduction

Section snippets

Plant material

General analytical methods

Extraction and purification of polysaccharides

Results and discussion

Acknowledgements

Phytochemistry

Food Chemistry

Carbohydrate Polymers

Eating Behaviors

Analytical Biochemistry

Carbohydrate Research

Journal of Biological Chemistry

Carbohydrate Research

Fitoterapia

Phytochemistry

Bioresource Technology

Ethnopharmacology

Carbohydrate Research

Carbohydrate Polymers

Carbohydrate Research