Perfil de substâncias fenólicas de méis brasileiros por cromatografia líquida de alta eficiência e avaliação do potencial antioxidante

Abstract

The evaluation of the antioxidant activity was carried out for four samples of wild honeys and five samples of orange honeys and the results were satisfactory both for the honey samples as well as for their extracts. The total phenolic contents were found to be higher for the wild samples in comparison with the citrus honeys. Total flavonoid content was found to be much less significant than that of phenolics, suggesting that, as far as brazilian honeys are concerned, phenolics are more abundant than flavonoids. The fact that the wild honeys show higher contents of phenolics may explain the higher antioxidant activity of those honeys, as indicated by the radical uptake ability (EC50). This ability could support their use as functional food. This work describes the identification of phenolics and flavonoids in three samples of wild honeys, three samples of eucalyptus honeys and seven samples of citrus honeys from different geographical regions, including atlantic Forest. The samples were analyzed by HPLC-PDA and UV-VIS spectrometry. The results obtained show that there is a large variation in the phenolic profiles of the different samples. The analysis of the chromatographic profile and of the UV-VIS spectra at 230-400 nm allowed the identification of phenolic acids and flavonoids in a single run of 25 minutes. In the wild honey samples were identified protocatechuic, para-hydroxybenzoic, vanylic, paracoumaric, para-methoxybenzoic and cinnamic acids and the flavonoids morin, quercetin, kaempferol and isoquercetin. In the eucalyptus honeys were identified protocatechuic, para-hydroxybenzoic and syringic acids together with the flavonoid tricetin. Finally, in the samples of citrus honeys the main acids identified were protocatechuic, parahydroxybenzoic and para-coumaric along with the flavonoids morin, quercetin, rutin and isoquercetin. This is the first report of the flavonoids isoquercetin and kaempferol (only one atlantic Forest sample) in brazilian honeys. Besides the chemical analyses described here, the polen analysis of the monofloral honeys (eucalyptus and citrus) were carried out in order to define and guarantee their botanical origin as well as their properties. Taking into consideration the participation of anemophilic and poliniferous polens as well as the quantitative relationship between nectariferous plants and their properties, a diagnosis is obtained which is very close to the real origin of the honey.