New ways to decipher plant and microbial metabolomes

The large chemical space occupied by Natural Products (NPs) is directly linked to the high variability of their intrinsic physicochemical properties that renders their separation, detection and characterization challenging. Profiling NPs in complex crude extracts requires efficient separation methods and informative detection methods (MS/NMR) for further dereplication. This need became even greater with the advent of metabolomics in natural product research. Our group has thus elaborated metabolomic strategies mainly based on rapid UHPLC-TOF-MS fingerprinting for a sensitive detection of biomarkers with appropriate data mining methods and further identification based on dereplication by MS and MS/MS or de novo identification by targeted microisolation and subsequent microflow NMR (CapNMR) analysis. The miniaturization of the analytical and isolation methods enabled us also to scale down the structural identification work to that of bioassay (microgram level) which fit, for example, with in vivo models such as Zebrafish. Some examples of our metabolomic strategy will be illustrated for challenging applications in relation to plant and fungi stress responses for the search for new biomarkers with interesting bioactivities. Discussion on possibilities and limits of the current approaches, the need for rational metabolite identification methods and the potential of systems biology in the field of Pharmacognosy will be presented.