HPTLC-MALDI/TOF/MS vs. HPLC-ESI/MS2 for identification to flavonoids in plant extracts

Flavonoids are secondary metabolites of great structural variety synthesized by plants with various biological activities. In phytochemistry, a first analysis by HPTLC is realized with chemical revelation to know the molecular family in the extract plant. Then if the extracts have an activity, they are frequently analyzed by HPLC-MS to deeper identification. The goal of this work was to develop a method involving a direct coupling of HPTLC to matrix assisted laser desorption and ionization time of flight mass spectrometry (MALDI/TOF/MS) for the characterization of flavonoids present in plant extracts. This coupling in addition to know the molecular family gives a direct molecular identification, when comparing different extracts, that is time saving. In this work, plants analyzed by HPTLC-MALDI/TOF/MS, were chosen recovering different flavonoid families (e.g. Hippophaë rhamnoides [1], Rose [2] – Flavonol; Lamiaceae – Flavone; Apple [3] – Dihydrochalcone; Garcinia Mangostana [4] – Xanthone; wine – Anthocyanidin). HPTLC plates were directly analyzed in positive or negative ionization mode on an Autoflex MS (Bruker Daltonik) in reflectron mode. These identifications were compared to analysis in HPLC-ESI/MS². In the apple extract, after revelation the plate presents a lot of yellow spots with ions at m/z 301 that shows the plenty in derivatives of quercetin. Thus 8 glycoside molecules with quercetin genin have been identified. Moreover coeluted minor compounds have been identified as phloridzin (chalcone) and afzelin. Hyphenation allowed to separate and identify 2 isobarics (Rf 0.3 and 0.41, m/z 447) with different genins confirmed by fragment ions, a quercetin rhamnose (m/z 301) and a kaempferol glucose (m/z 285) in rose extract. The identification of plant samples was in good accordance with studies already performed in our laboratory in HPLC-ESI/MS².

In this context, the direct coupling HPTLC-MALDI/TOF/MS is a powerful and fast tool to determine composition of plant extracts.

Keywords: Flavonoid, HPTLC-MALDI/TOF/MS, HPLC/MS/MS.

References:

[1] Michel T, Destandau E, Elfakir C. On-line hyphenation of centrifugal partition chromatography and high pressure liquid chromatography for the fractionation of flavonoids from Hippophaë rhamnoides L. berries. J Chromatogr A 2011; 1218: 6173 – 6178

[2] Riffault L, Destandau E, Pasquier L, André P, Elfakir C. Phytochemical analysis of Rosa hybrid cv. “Jardin de Granville” by HPTLC, HPLC-DAD and HPLC-ESI-HRMS: Polyphenolic fingerprints of six plant organs. Phytochem 2014; 99: 127 – 134

[3] Grigoras C-G, Destandau E, Fougère L, Elfakir C. Evaluation of apple pomace extracts as a source of bioactive compounds. Ind Crops and Prod 2013; 49: 794 – 804

[4] Michel T, Destandau E, Fougère L, Elfakir C. New “hyphenated” CPC-HPLC-DAD-MS strategy for simultaneous isolation, analysis and identification of phytochemicals: application to xanthones from Garcinia mangostana. Anal Bioanal Chem 2012; 404: 2963 – 2972