Effect of cranberry (Vaccinium macrocarpon) oligosaccharides on the formation of advanced glycation end-products

BACKGROUND: The formation and accumulation of advanced glycation end-products (AGEs) are implicated in several chronic human illnesses including type-2 diabetes, renal failure, and neurodegenerative diseases. The cranberry (Vaccinium macrocarpon) fruit has been previously reported to show anti-AGEs effects, attributed primarily to its phenolic constituents. However, there is lack of similar data on the non-phenolic constituents found in the cranberry fruit, in particular, its carbohydrate constituents. Herein, a chemically characterized oligosaccharide-enriched fraction purified from the cranberry fruit was evaluated for its potential anti-AGEs and free radical scavenging effects. OBJECTIVE: The aim of this study was to evaluate the in vitro anti-AGEs and free radical scavenging effects of a chemically characterized oligosaccharide-enriched fraction purified from the North American cranberry (Vaccinium macrocarpon) fruit. METHOD: The cranberry oligosaccharide-enriched fraction was purified from cranberry hull powder and characterized based on spectroscopic and spectrometric (NMR, MALDI-TOF-MS, and HPAEC-PAD) data. The oligosaccharide-enriched fraction was evaluated for its anti-AGEs and free radical scavenging effects by the bovine serum albumin-fructose, and DPPH assays, respectively. RESULTS: Fractionation of cranberry hull material yielded an oligosaccharide-enriched fraction named Cranf1b-CL. The H-1 NMR and MALDI-TOF-MS revealed that Cranf1b-CL consists of oligosaccharides ranging primarily from 6-mers to 9-mers. The monosaccharide composition of Cranf1b-CL was arabinose (25%), galactose (5%), glucose (47%) and xylose (23%). In the bovine serum albumin-fructose assay, Cranf1b-CL inhibited AGEs formation in a concentration-dependent manner with comparable activity to the synthetic antiglycating agent, aminoguanidine, used as the positive control (57 vs. 75%; both at 500 mu g/mL). In the DPPH free radical scavenging assay, Cranf1b-CL showed superior activity to the synthetic commercial antioxidant, butylated hydroxytoluene, used as the positive control (IC50 = 680 vs. 2200 mu g/mL, respectively). CONCLUSION: The in vitro anti-AGEs and free radical scavenging effects of cranberry oligosaccharides support previous data suggesting that these constituents may also contribute to biological effects of the whole fruit beyond its phenolic constituents alone. Also, this is the first study to evaluate a chemically characterized oligosaccharide fraction purified from the North American cranberry fruit for anti-AGEs and free radical scavenging properties.