Flavonoid profile and antioxidant activity of nectar honey from various regions of Greece and Algeria

The The first part of this research discuses flavonoid profiles in different honey samples and their possible use as markers for honey floral origin. The flavonoids of forty honey samples from different botanical and geographical areas (thyme honeys from Greece and trifolium, eucalyptus, and linden honey from Algeria) were analysed by reversed-phase IIPLC, coupled with UV-vis diode array detection and mass spectrometry (MS). The flavonoid fraction was isolated by a combination of separation on a non-ionic polymeric resin (Amberlite XAD-4) column and liquid/liquid extraction with ethyl ether. Twenty-eight flavonoids have been detected, eleven of which have been completely identified: the flavanones: naringenin, pinocembrin in and hesperetin; the flavonols: quercetin, isorhamnetin, and kaempferol; and the flavones: luteolin, diosmetin, circiliol, apigenin, and chrysin. The total amount of flavonoids ranged between between 420 and 3028 mcg/100g honey. The highest concentration of flavonoids was found in linden honey (Tilia sp.) from Algeria while the lowest was in adulterated thyme honey (made from sugar-fed bees during thyme nectar flow) from West Crete (Greece). The main flavonoids present in authentic thyme honey were quercetin, naringenin, pinocembrin and an unknown flavone with a MW of 270. Salamina honey samples were the richest in flavonoid content in all the thyme honey tested. In general, the phenolic profiles of the honeys of the same floral origin (thyme) were characteristically similar. This common profile comprising quercetin, naringenin, pinocembrin and an unknown flavone with a MW of 270 can be found in thyme honeys, which could be floral markers for Greek thyme honeys. These results have further revealed that the HPLC analysis of honey flavonoid constituents might be used individually and/or jointly for the authentication of the botanical origins of honeys.