1: J Chromatogr A. 2008 Nov 7;1210(1):45-54. Epub 2008 Sep 20.

Analysis of minor flavonoids in Piper hostmannianum var. berbicense using liquid 
chromatography coupled with atmospheric pressure chemical ionization mass
spectrometry.

Portet B, Fabre N, Rozenberg R, Habib-Jiwan JL, Moulis C, Quetin-Leclercq J.

Université de Toulouse, UMR-152 IRD-UPS Laboratoire de Pharmacochimie des
Substances Naturelles et Pharmacophores Redox, Faculté des Sciences
Pharmaceutiques, Université Paul-Sabatier, F-31062 Toulouse cedex 09, France.
benedicte.portet@voila.fr

The fragmentations of hydroxylated flavanones, chalcones and dihydrochalcones
were investigated by direct loop injection using an ion trap mass spectrometry
equipped with atmospheric pressure chemical ionization (APCI) probe. Some of them
have been isolated from the leaves of Piper hostmannianum var. berbicense and
standards were used to confirm their fragmentation behaviour. In negative ion
mode, fragmentations of these three types of flavonoids revealed specific
diagnostic ions which allowed us to identify aglycones in a crude plant extract. 
The major fragment ion obtained in MS/MS experiment for methoxylated chalcones is
the neutral loss of a methyl radical whereas a H(2)O molecule is lost in the case
of methoxylated dihydrochalcones. Methoxylated chalcones and flavanones isomers
could be differentiated by the relative intensity ratio of [M-H-CH(3)]*(-) and
[M-H-C(2)H(2)O](-) ions. Based on UV and MS data, a decision tree that includes
UV lambda(max) absorptions and MS/MS diagnostic ions was built in order to obtain
structural information of unknown compounds present in the extract. This tree was
used to identify flavonoids in the ethyl acetate extract of P. hostmannianum var.
berbicense leaves after analysis by high-performance liquid chromatography-diode 
array detection-atmospheric pressure chemical ionization ion trap multistage mass
spectrometry. A total of 11 flavonoids were tentatively characterized based on
the MS fragmentations pattern observed in MS(n) experiments.


PMID: 18838145 [PubMed - indexed for MEDLINE]

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