Chemical constituents of selected unifloral Greek bee-honeys with antimicrobial activity.

(±)-3-Hydroxy-4-phenyl-2-butanone (1) and (+)-8-hydroxylinalool (2) were isolated from Greek honey samples and their structures were determined by spectroscopic and mass spectrometry methods. The enantiomeric ratio of 1 and 2 was determined using chiral GC-MS. Compound 1 has recently been proposed as a possible chemical marker of thyme honey, but although 1, in our hands, was identified only in monofloral thyme honey amongst the honey samples, it was not found in all studied thyme honey samples and additionally its origin was not directly associated with thyme, proving that compound 1 should not be considered as an unambiguous marker of thyme honey. Compound 2 was isolated and identified as the (+)-6S isomer only in monofloral citrus honey. The combination of (+)-8-hydroxylinalool with methyl anthranilate and caffeine could be proposed as a fingerprint marker for the description of citrus honey. All studied honey extracts and the isolated compounds were also tested for their antimicrobial activity.