Characterization and quantification of phenolic compounds of honeys from Sierra Nevada (Granada)

Honey is a natural substance to which antioxidant, anti-inflammatory and antimicrobial effects, among others, have been attributed. These beneficial effects are attributed especially to its content of bioactive compounds, mainly phenolic compounds, whose content varies greatly depending on the variety, origin, agronomic conditions, harvest season, and climate. Despite some researchers have analysed the content of bioactive compounds in Spanish honeys, there are no previous studies on the content of those compounds in honeys from Sierra Nevada. Thus, the aim of the present study was to characterise 21 honeys from Sierra Nevada (Granada). The characterization of phenolic compounds was performed by high performance liquid chromatography coupled to quadrupole-time of flight mass spectrometry (HPLC-ESI-QTOF-MS). The mass accuracy and true isotopic pattern in both MS and MS/MS spectra provided by QTOF-MS made possible the tentative identification of different compounds in the studied honeys. Six analytical standards were employed for estimating the amount of phenolic compounds present in the honeys. Sixty-four phenolic compounds were characterized, including flavonoids, phenolic acids, and derivatives, among others. Among them, 4 compounds were tentatively identified for the first time in honey: kaempferol-rhamnose, tectoridin and divanillin isomers. Flavonoids represented more than 86.8 % of the bioactive compounds quantified in the honeys. The most abundant compounds were pinobanksin (16.88±3.15 µg/g), genistein/baicalein (13.27±4.91 µg/g), pinocembrin (12.33±2.92 µg/g), chrysin (12.23±2.13 µg/g) and carnosol (9.52±2.90 µg/g). Due to their interesting composition, more studies are necessary to determine if the extreme environmental conditions from Sierra Nevada, such as UV radiation, extreme temperature, or altitude (hypoxia) pose abiotic stress for the plants located there fostering the concentration in phenolic compounds.