A structure-oriented approach for the accelerated and focused isolation of possible bioactive natural products based on UHPLC-HRMS/MS methods

The high impact of Natural Products (NP) in medicine is proven and well sustained [1]. NP are characterized by unique structural diversity and critical drug-like features which rank them as the most promising candidates for possible future drugs [2]. However, several factors constrain their development related mostly to the time-consuming and labor procedures required for their isolation, the high cost and the dereplication problem [3]. In the present work, we propose a structure-oriented approach using UHPLC-HRMS/MS (LTQ-Orbitrap) methodologies trying to release the entire procedure from repeated and unuseful isolation steps and pursuing the targeted determination of the possible bioactive compound. This approach is applied in crude extracts and is based on fast UHPLC methods, high resolution mass spectra and ms/ms accurate mass measurements. As a proof of concept, the Cameroonian tree Amphimas pterocarpoides Harms (Leguminosae) was selected and flavonoids – isoflavonoids were chosen as the chemical class of interest. Based on a chromatographic (Rt, polarity) and spectrometric features (UV, accurate m/z, proposed ECs, RDB values and RIAS) as well as ms/ms spectra, the compounds of interest were defined and structurally elucidated. 12 of the 17 traced flavonoids were selectively isolated and characterized using 1 and 2D NMR techniques verifying our concept. Applying this approach, the identification of target-compounds is achieved early in the discovery procedure facilitating the dereplication of known compounds. Consequently much time required for the fractionation, isolation and purification is saved while the possibility of the discovery of novel structures and subsequently novel actives is elevated.

References: [1] Newman DJ, Cragg GM (2007)J Nat Prod 70: 461–477.

[2] Yuliana ND, Khatib A, Choi YH and Verpoorte R (2011) Phytother Res 25: 157–169.

[3] Potterat O and Hamburger M, (2006) Current Organic Chemistry 10: 899–920.