Solid-phase extraction of antioxidant compounds from commercial cranberry extract and its antiradical activity

This study is concerned with the fractionation and determination of major antioxidant compounds (phenols, flavonoids, anthocyanins and vitamin C) in commercial cranberry extract. The total content of phenolics, flavonoids and total and monomers of anthocyanins, determined spectrophotometrically, was 1.67 mg/g, 0.41 mg/g, 5.12 mg/g and 3.32 mg/g. The content of vitamin C, determined volumetrically, was 121.74 mg/g. Commercial cranberry extract was dissolved in 80 % acetone and the solution was fractionated using solid phase extraction (SPE) in order to abstract vitamin C, neutral and acidic phenols. The free radical scavenging activity of the cranberry extract and its fractions was investigated on stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) and reactive hydroxyl radicals employing electron spin resonance (ESR) spectroscopy. The most effective fractions were those containing vitamin C (AADPPH= AAOH=100%), neutral (AADPPH=89.50% and AAOH=43.11%) and acidic (AADPPH=83.98% and AAOH=38.58%) phenols. The presence of vitamin C, abstracted from cranberry extract, was determined by Fe(III)-mediated ascorbate oxidation which yields characteristic ESR doublet spectrum of ascorbyl radical