Untargeted Characterization and Biological Activity of Amazonian Aqueous Stem Bark Extracts by Liquid and Gas Chromatography–Mass Spectrometry

Introduction: Aqueous stem bark extracts of Aspidosperma rigidum Rusby, Couroupita guianensis Aubl., Monteverdia laevis (Reissek) Biral, and Protium sagotianum Marchand have been reported as traditional remedies in several countries of the Amazonian region. Despite previous research, further investigation to characterize secondary metabolites and the biological activity of extracts is needed to derive potential applications. Material and Methods: Metabolic profiling was carried out using liquid and gas chromatography coupled with mass spectrometry (UHPLC–MS/MS and GC–MS). The chemical composition of the studied plants was further compared by principal component analysis (PCA). Additionally, chemical profiles were correlated with antimicrobial and toxicity activities, which suggested potential metabolites for future research. Results: We identified 16 and 32 compounds by UHPLC–MS/MS and GC–MS analysis, respectively. Antimicrobial activity was detected in three stem bark extracts. C. guianensis showed inhibition of all tested microorganisms, including antibiotic-resistant strains. Molecular networking approaches, in silico tools, and Pearson's correlation showed that antifungal compounds could be a terpene glycoside (r = 0.918) and/or a phenolic (r = 0.882) metabolite class. Conclusion: This study highlights the use of the established procedure in exploring the metabolomes of these species, which could be a novel source of antimicrobial drug discovery. Coupling the observed biological potential with UHPLC–MS/MS data has also accelerated the tracing of their bioactive compounds. These findings update the state of the art regarding the chemical composition and biological activity of the plant extracts, defining potential new applications for the pharmaceutical applications.