Structure-oriented UHPLC-LTQ-orbitrap-based approach for the identification of isoflavonoids from Amphimas pterocarpoides

Hyphenated techniques and especially UHPLC-MS methods are nowadays widely employed in natural products research. However, the complex nature of plant extracts complicates considerably the analysis and the identification of their constituents. Nevertheless, new MS analyzers with increased resolving power and accuracy such as the orbital trap (Orbitrap) could facilitate this process. The objective of this study is the development of a new structure-oriented approach based on fast UHPLC-HRMS/MS methodologies for the identification of flavonoids in crude extracts. Additionally, aims to assist dereplication procedures and orient the focused isolation of natural products. As a proof of concept, Amphimas pterocarpoides methanolic extract was selected. Based on a chromatographic and spectrometric features (Rt, UV, accurate m/z, proposed EC, RDBeq., RIA) as well as HRMS/MS spectra, several isoflavonoids were identified. In order to verify the proposed structures 11 isoflavonoids were selectively isolated and unambiguously identified using 1&2D NMR techniques. A further study these isolated isoflavonoids was carry out in HRMS/MS level, employing ESI and APCI sources, in both modes and useful information regarding their fragmentation patterns as well as their diagnostic ions were obtained. The proposed Orbitrap-based dereplication strategy could comprise a novel approach for the analysis of crude extracts.