UHR-Q-TOF Analysis Can Address Common Challenges in Targeted and Untargeted Metabolomics

Here, we present an ESI-UHR-Q-TOF based analysis of myxobacterial secondary metabolites, which permits to solve several challenges frequently encountered in metabolite profiling studies. Myxobacteria are promising producers of natural products exhibiting potent biological activities, and several myxobacterial metabolites are currently under investigation as potential leads for novel drugs. However, the myxobacteria are also a striking example for the divergence between the genetic capacity for the production of secondary metabolites and the number of compounds that could be characterised to date. Wild type and mutant strains were analyzed concerning the production patterns of known metabolites and with regard to the discovery of new metabolites. Sample throughput: Since mass accuracy and resolution of TOF instruments are independent of the acquisition rate, they are perfectly suited for a coupling to UHPLC separations. These hyphenations enable a reduction of analysis time in combination with a high chromatographic resolution and therefore permit an increased sample throughput. The UHR-TOF analysis revealed that an acquisition rate of up to 20Hz did not compromise the achieved mass accuracy or resolution. Targeted and untargeted metabolite profiling: Acquisition of full scan accurate mass spectra enable the targeted screening for known compounds e.g. from the class of DKxanthenes based on very selective high resolution EIC (hrEIC) traces with small mass windows of 1.0–0.5mDa. A comparison of several datasets following a “comprehensive feature extraction” combined with a statistical analysis permits an untargeted discovery of novel biomarkers using the same data files as for the targeted analysis. Identification: Even a mass accuracy of 0.1ppm is not sufficient for an unambiguous formula identification for m/z values above 500. A combination of accurate mass data and isotopic pattern information in MS and MS/MS spectra can extend this m/z range for reliable formula suggestions. Examples for novel metabolites from Myxobacteria will be shown.