NMR and UPLC-qTOF-MS/MS characterisation of novel phenylethanol derivatives of phenylpropanoid glucosides from the leaves of strawberry (Fragaria x ananassa cv. Jonsok).
BACKGROUND
Strawberry (Fragaria x ananassa) is rich in polyphenols, particularly anthocyanins, flavonols, condensed tannins and ellagic tannins. In addition to the fruits, the leaves of strawberry also contain a wide range of phenolic compound classes, but have not been investigated to the same extent as the fruit.


OBJECTIVE
To characterise a metabolite group present in the leaves of strawberry, that was not amenable for identification based on earlier information available in the literature.


METHODS
Methanolic extracts of strawberry leaves were analysed by UPLC-qTOF-MS/MS and iterative quantum mechanical NMR spectral analysis.


RESULTS
The structures of phenylethanol derivatives of phenylpropanoid glucosides Eutigoside A ( F4) and its two isomeric forms 2-(4-hydroxyphenyl)ethyl-[6-O-(Z)-coumaroyl]-beta-D-glucopyranoside (F6) and 4-(2-hydroxyethyl)phenyl-[6-O-(E)-coumaroyl]-beta-D-glucopyranoside (F1) were resolved by NMR and UPLC-qTOF-MS/MS. In addition, two other derivatives of phenylpropanoid glucosides similar to Eutigoside A but possessing different phenolic acid moieties, namely Grayanoside A ( F5) and 2-(4-hydroxyphenyl)ethyl-[6-O-(E)-caffeoyl]-beta-D-glucopyranoside (F14), were similarly identified. Also, accurate characteristic coupling constants for the subunits are reported and their usefulness in structural analysis is highlighted.


CONCLUSIONS
Chemical analysis of the leaves of strawberry (Fragaria x ananassa cv. Jonsok) resulted in the identification of a compound class, phenylethanol derivatives of phenylpropanoid glycosides, not previously found in strawberry.
Hanhineva
Kati
K
Department of Biosciences, University of Kuopio, Kuopio, Finland. kati.hanhineva@uku.fi
Soininen
Pasi
P
Anttonen
Mikko J
MJ
Kokko
Harri
H
Rogachev
Ilana
I
Aharoni
Asaph
A
Laatikainen
Reino
R
Kärenlampi
Sirpa
S
D002109:Caffeic Acids / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003374:Coumarins / Q000032:analysis* / Q000737:chemistry*; D031985:Fragaria / Q000737:chemistry*; D005960:Glucosides / Q000032:analysis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D000432:Methanol / Q000737:chemistry; D010636:Phenols / Q000737:chemistry; D010626:Phenylethyl Alcohol / Q000032:analysis* / Q000737:chemistry; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry*; D020005:Propanols / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
C546804:2-(4-hydroxypheny)ethyl-(-O-(E)-caffeoryl)-b-D-glucopyranoside; D002109:Caffeic Acids; D003374:Coumarins; D005960:Glucosides; D010636:Phenols; D010936:Plant Extracts; D020005:Propanols; C505498:eutigoside A; D010626:Phenylethyl Alcohol; D000432:Methanol