Structural Characterization of Cranberry Arabinoxyloglucan Oligosaccharides.
Cranberry ( Vaccinium macrocarpon) products are widely available in North American food, juice, and dietary supplement markets. The use of cranberry is popular for the prevention of urinary tract infections (UTIs) and other reported health benefits. Preliminary findings by our research group indicate that arabinoxyloglucan oligosaccharides are present in cranberry products and may contribute to the antiadhesion properties of urine produced after cranberry consumption, but relatively little is known regarding the oligosaccharide components of cranberry. This report describes the isolation from two cranberry sources and the complete structure elucidation of two arabinoxyloglucan oligosaccharides through the use of carbohydrate-specific NMR spectroscopic and chemical derivatization methods. These compounds were identified as the heptasaccharide beta-d-glucopyranosyl-(1->4)-[alpha-d-xylopyranosyl-(1->6)]-beta-d-glucopyranosyl-(1->4)-beta-d-glucopyranosyl-(1->4)-[alpha-l-arabinofuranosyl-(1->2)-alpha-d-xylopyranosyl-(1->6)]-beta-d-glucopyranose (1) and the octasaccharide beta-d-glucopyranosyl-(1->4)-[alpha-l-arabinofuranosyl-(1->2)-alpha-d-xylopyranosyl-(1->6)]-beta-d-glucopyranosyl-(1->4)-beta-d-glucopyranosyl-(1->4)-[alpha-l-arabinofuranosyl-(1->2)-alpha-d-xylopyranosyl-(1->6)]-beta-d-glucopyranose (2). Selected fractions and the isolated compounds were subjected to antimicrobial, cell viability, and E. coli antiadhesion assays. Results indicated that enriched fractions and purified compounds lacked antimicrobial and cytotoxic effects, supporting the potential use of such compounds for disease prevention without the risk for resistance development. Preliminary antiadhesion results indicated that mixtures of oligosaccharides exhibited greater antiadhesion properties than purified fractions or pure compounds. The potential use of cranberry oligosaccharides for the prevention of UTIs warrants continued investigations of this complex compound series.