The subfamily Barnadesioideae (Asteraceae) encompasses more than 90 species distributed in nine genera entirely restricted to South America. This group constitutes the earliest diverging lineage of the family Asteraceae [1] . Some reports describe Barnadesioideae as a group with “simple” phytochemistry, and associated this possible character to its basal position [2] . This study aimed to employ untargeted metabolomics as a chemotaxonomic tool to reveal the intergeneric relationships of the subfamily Barnadesioideae and explore its phytochemical composition. Representative samples of six genera of the subfamily Barnadesioideae were processed for obtaining their metabolic fingerprints by LC-ESI-HRMS. Two different extraction solvents and chromatographic methods were tested to assess their impact in the final chemotaxonomic classification of Barnadesioideae. The negative mode datasets were treated for baseline correction, chromatogram deconvolution, peaks alignment, and data normalization before exploratory (HCA and PCA) and supervised (OPLS-DA) analyses. The cluster groups observed in the HCA and PCA resembled the intergeneric relationships proposed by Gruenstaeudl et al., 20091 based on morphological and molecular markers, demonstrating that untargeted metabolomics can be used as an auxiliary tool to study the intergeneric relationships of the subfamily Barnadesioideae. Based on the OPLS-DA, phenolic compounds (Fig. 1) were recognized as possible chemotaxonomic markers. Contrary to previous reports, the metabolome annotation of the subfamily Barnadesioideae revealed a complex phytochemical scenario. Furthermore, the extraction solvent and chromatographic elution program displayed a significant impact in the metabolomics-based chemotaxonomic classification of the subfamily Barnadesioideae.
Fig. 1 Phenolic compounds in the subfamily Barnadesioideae
Acknowledgements: FAPESP (Grants# 2014/16850-6 and 2014/26866-7) for funding.
References:
[1] Gruenstaeudl M, Urtubey E, Jansen RK et al. Phylogeny of Barnadesioideae (Asteraceae) inferred from DNA sequence data and morphology. Mol Phylogenet Evol 2009; 51:572-587.
[2] Calabria LM, Emerenciano VP, Ferreira MJP et al. A phylogenetic analysis of tribes of the Asteraceae based on phytochemical data. Nat Prod Commun 2007; 2:277-285.