From linden flower to linden honey. Part 2: Glycosidic precursors of cyclohexa-1,3-diene-1-carboxylic acids.
The presence of two unusual, recently identified terpene acids, i.e., 4-(1-hydroxy-1-methylethyl)cyclohexa-1,3-diene-1-carboxylic acid (1) and 4-(1-methylethenyl)cyclohexa-1,3-diene-1-carboxylic acid (2), was now also confirmed in (Swiss) linden honey, after solid-phase extraction and HPLC purification. NMR Spectroscopy, in combination with UPLC/MS analysis, showed the presence of several glycosides of 1, which accounted for ca. 0.6 weight-% of the honey, as quantified by UPLC-UV. The major 'glycoside' of 1, compound 5, could be isolated and identified by 2D-NMR experiments as the corresponding beta-gentiobiosyl ester (rather than the classical compound with a glycosidic bond between an aglycone OH group and the sugar). The same diglycosides found in linden honey were also detected in linden nectar; also, chestnut and fir honeys contained these glycosides in minor quantities, but not colza, acacia, or dandelion honeys (Table 2).
Frérot
Eric
E
Firmenich SA, Corporate R&D Division, P.O. Box 239, CH-1211 Geneva 8. eric.frerot@firmenich.com
Velluz
Alain
A
Decorzant
Erik
E
Naef
Regula
R
D002264:Carboxylic Acids / Q000032:analysis / Q000737:chemistry*; D035264:Flowers; D006027:Glycosides / Q000032:analysis / Q000737:chemistry*; D006722:Honey / Q000032:analysis; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry; D032384:Tilia
D002264:Carboxylic Acids; D006027:Glycosides; D010936:Plant Extracts