Combination of matrix solid-phase dispersion extraction and direct on-line liquid chromatography–nuclear magnetic resonance spectroscopy–tandem mass spectrometry as a new efficient approach for the rapid screening of natural products:

Determination and identification of isoflavonoids in Radix astragali by matrix solid-phase dispersion extraction and high-performance liquid chromatography with photodiode array and mass spectrometric detection

“…Therefore, it simplifies the extraction and clean-up steps, reduces sample manipulation and is faster than conventional techniques. Recently, this method was combined with on-line liquid chromatography-nuclear magnetic resonance spectroscopy-tandem mass spectrometry (LC-NMR-MS-MS) to rapidly screen the total asterosaponin fraction of the starfish Asterias rubens [10].…”

“…To speed up the isolation, purification, and characterization of bioactive natural products, a high-throughput method, which integrated many advanced technologies for the production and analysis of large natural product libraries was reported recently [11]. In this complicated procedure, one of the most successful techniques is the coupling of HPLC with photodiode detection (LC-DAD), atmospheric pressure ionization (API) mass spectrometry (LC-API-MS) and nuclear magnetic resonance spectrometry (LC-NMR) [10,[12][13][14][15].…”

Capillary liquid chromatography–microcoil 1H nuclear magnetic resonance spectroscopy and liquid chromatography–ion trap mass spectrometry for on-line structure elucidation of isoflavones in Radix astragali

“…These two techniques have traditionally been the primary tools used by natural product chemists to isolate and determine the structures for molecules of interest. Recent advances in NMR technology allow the robust practical application of HPLC-NMR, thus providing natural product chemists with a powerful on-line structure elucidation tool in the field of phytochemistry [11][12][13][14]. However, a major drawback of this technique is still the inherently rather lower sensitivity of the NMR detector as well as the necessity for elaborate solvent signal suppression.…”

Two new asterosaponins from the starfish Asterias rubens: application of a cryogenic NMR probe head

“…1 In our search for new biologically active asterosaponins of the Baltic starfish Asterias rubens, we have recently developed a structure-guided approach of chemical screening by means of coupled liquid chromatography-NMR-mass spectrometry (LC-NMR-MS). 2 In order to recognize the presence of new compounds at the earliest possible stage and thereby avoid unnecessary preparative work, either total asterosaponin fractions 3 or partly purified saponin subfractions are submitted to on-flow LC-NMR-MS. The proton NMR spectra provided by LC-NMR proved to be well suited for these purposes: as asterosaponins possess the same steroidal nucleus, and differ only in their steroidal side-chain or their glycosidic moiety, unknowns are readily identified by comparison of their subspectra with those of already known compounds because repeating signal patterns of identical glycosidic moieties or side-chains are easily recognized.…”