Characterisation of the phenolic and flavonoid fractions and antioxidant power of Italian honeys of different botanical origin

BACKGROUND: Twenty-seven Italian honey samples of different floral origin were analysed for total phenolic and flavonoid contents by a spectrophotometric method and for antioxidant power and radical-scavenging activity by the ferricreducing/antioxidant power(FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays respectively. In addition, the phenolic and flavonoid profiles were analysed using high-performance liquid chromatography with UV detection (HPLC-UV). RESULTS: The results of this study showed that honey contains copious amounts of phenolics and flavonoids. HPLC-UV analysis showed a similar qualitative polyphenolic profile for all honey samples analysed. The main difference among samples was in the contribution of individual analytes, which was affected by floral origin. Total phenolic and flavonoid contents varied from 60.50 to 276.04 mg gallic acid equivalent kg(-1) and from 41.88 to 211.68 mg quercetin equivalent kg(-1) respectively. The antioxidant capacity was high and differed widely among samples. The FRAP value varied from 1.265 to 4.396 mmol Fe2+ kg(-1), while the radical-scavenging activity expressed as DPPH-IC50 varied from 7.08 to 64.09 mg mL(-1). Correlations between the parameters analysed were found to be statistically significant (P < 0.05). CONCLUSION: The present study shows that honey contains high levels of phenolics and flavonoids and that the distribution of these compounds is influenced by the honey's floral origin. (C) 2009 Society of Chemical Industr