An integrated high resolution mass spectrometric and bioinformatic approach for the rapid identification of flavonoids in plant extract

Abstract

An integrated and fully automated high resolution mass spectrometric and bioinformatic approach was set‐up for the rapid and unequivocal identification of flavonoids and other phenol compounds in plant extract. The approach consists of the following steps: 1) direct infusion of the extract into an Orbitrap mass analyzer (resolution 100,000; negative ion‐mode, ESI source); 2) automated identification of the monoisotopic masses and of the corresponding isotopic patterns by a Boolean logic algorithm; 3) searching the experimental monoisotopic masses (tolerance 5 ppm) in a database of flavonoids (http://www.phenol‐explorer.eu/compounds; http://www.metabolome.jp/download/flavonoid/) implemented with phenol compounds (i.e. chalcons). Final identification is achieved by matching the isotopic pattern and by MS/MS fragmentation studies. In particular, experimental MS/MS fragments are matched with those retrieved by the data base http://www.massbank.jp and by the predicted ions obtained by the software ACD/MS‐fragmenter. The method was firstly validated by mixtures of standard polyphenols and was then applied for the identification of phenols and flavonoids contained in an EtOH extract of Angelica keiskei. The method can also be used for semiquantitative analysis using Trolox as internal standard. [Supported by USDA ARS #58‐1950‐7‐707, USA and BioGreen 21 #20070301034009 RDA, Korea]