Investigation of the alkaloid composition of Strychnos genus using molecular networking, a mapping method for molecules

Molecular networking is a chemometric technique which is now applied to the field of medicinal plants. With the contribution of the team of Pharmacognosy from ULiege regarding compounds from plants of the Strychnos genus (Loganiaceae family), the University of Paris-Sud implemented a spectral database focused on monoterpene indole alkaloids, called MIADB, available on the GNPS online platform and on MetaboLights. This database offers the possibility to annotate extracts and to quickly discriminate unknown alkaloids by comparison of tandem mass spectra. In this way, the ERDF project « Tropical Plant Factory » has the objective of isolating new natural compounds, using this approach as an effective guidance. Therefore, the first step of my work consisted in the elaboration of a methodology to identify highly original compounds from the genus using this technique. Forty-four extracts of Strychnos, prepared with the SpeedExtractor E-914, were profiled by (UP)LC-ESI-Q-TOF-MS/MS. The resulting MS/MS data were pre-processed using the “MZmine 2” software, organized as a single molecular network through the GNPS online platform and displayed on the “Cytoscape” software. The molecular network obtained allowed to choose the interesting extracts, which alkaloids of interest will be isolated with a combination of bioassay-guided fractionation interfaced with mass-guided approach.