Identification of flavonoid markers for the botanical origin of Eucalyptushoney

European Eucalyptus honeys showed a common and characteristic HPLC profile in which the flavonoids myricetin (3,5,7,3',4',5'-hexahydroxyflavone), tric etin (5,7,3',4',5'-pentahydroxyflavone), quercetin (3,5,7,3',4'-pentahydrox yflavone), luteolin (5,7,3',4'-tetrahydroxyflavone), and kaempferol (3,5,7, 4'-tetrahydroxyflavone) were identified. Their contents, and relative amoun ts, in the analyzed honey samples were quite constant and supported their f loral origin. In addition, ellagic acid and the propolis-derived flavonoids pinobanksin, pinocembrin, and chrysin were detected in most samples. The c ontents of these nonfloral phenolics were much more variable as could be ex pected for their propolis origin. Myricetin, tricetin, and luteolin had not been identified as floral markers in any other honey sample previously ana lyzed in our laboratory (chestnut, citrus, rosemary, lavender, acacia, rape seed, sunflower, heather, lime tree, etc,) or reported in the literature, s uggesting that these could be useful markers. Only in some individual heath er samples produced in Portugal has tricetin previously been detected in mi nor amounts. These samples, however, were contaminated with Eucalyptus as r evealed by their pollen analysis and the lack of tricetin or their glycosid es in heather floral nectar. It remains to be established if myricetin, tri cetin, and luteolin originate from Eucalyptus floral nectar where the corre sponding glycosides should be present.