Matrix free laser desorption ionization assisted by 13C NMR dereplication: A complementary approach to LC-MS2 based chemometrics

The identification of bioactive constituents from complex mixtures of Natural Products (NPs) is an important field of applied chemometrics. It requires the thorough chemical analysis of sample material, which is generally facilitated by liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-MS2). Providing a simple and time efficient complementary approach, the current work presents the use of matrix free laser desorption ionization mass spectrometry (LDI-MS) within a chemometric model that allows the identification of activity markers in complex mixtures. As a working example the correct prediction and consecutive isolation of NPs with notable anti-AGEs effects from crude bark extracts of Garcinia parvifolia is discussed. Results were thoroughly compared to those obtained by a concurrently performed LC-MS2 analyses. In addition, the 13C NMR dereplication tool MixONat was successfully used to confirm the structures of high yield activity markers directly from complex mixtures prior to their isolation. Overall LDI-MS yielded comparable results to LC-MS2 and should be considered as complementary technique in applied chemometrics.