Planta Med 2011; 77 - PA49
DOI: 10.1055/s-0031-1282245

Combination of LC retention, high resolution TOF-MS information and web database search as dereplication tools in a chemotaxonomic study of Lippia spp

P Eugster 1, C Funari 2, F Mattioli 2, G Durigan 3, S Martel 1, P Carrupt 1, D Silva 2, J Wolfender 1
  • 1School of Pharmaceutical Sciences, EPGL, University of Geneva, University of Lausanne, 30 quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland
  • 2NuBBE – Nucleo de Bioensaios, Biossintese e Ecofisiologia de Produtos Naturais, Institute of Chemistry, São Paulo State University, Araraquara, SP, CP 355, CEP 14801–970, Brazil;
  • 3Instituto Florestal, Floresta Estadual de Assis, CP 104, CEP 19802–970 Assis, SP, Brazil.

Dereplication of natural products (NPs) in crude plant extracts represents a key process to rationalize bioactivity guided isolation procedures [1]. This process is efficient using LC-MS, notably with instrument specific MS/MS databases, but libraries of spectra have to be built or rebuilt from large collection of pure standards. In order to evaluate how far NP annotations can be made from a single LC-MS profiling using high resolution (HR)MS, online molecular formula assignment and LC-retention-based methods were evaluated in the frame of a chemotaxonomic study on various Lippia species from Brazil. In this respect, metabolite profilings were recorded on all crude extracts by HR-UHPLC-TOF-MS using generic long gradient and MS conditions. The high mass accuracy of the TOF-MS routinely provides exact mass determination below 10 ppm, corresponding to 5–50 putative molecular formulae per mass detected. To reduce this large number of formulae, heuristic filters were applied, which took into account statistics on characteristic compositional features of organic compounds and database information of existing NPs [2]. This approach mainly reduced the possible hits to one single molecular formula. Search in web databases with chemotaxonomic information provided a few possible NPs for each formula. These were discriminated by retention information, based on the well-known log P – retention relationship [3], comparing the calculated log P of known compounds of the extract with the calculated log P of putative structures. This procedure has been used in a chemotaxonomic study of Brazilian Lippia species and more than 40 compounds were annotated in this way.

References: 1. Wolfender JL (2009) Planta Med 75: 719.

2. Kind T, Fiehn O (2007) BMC Bioinformatics 8: 20.

3. Martel S et al. (2008) Chromatographic Approaches for Measuring log P, in Molecular Drug Properties – Measurement and Prediction. Ed. R. Mannhold, Wiley-VCH, Weinheim, Germany.