Caracterização estrutural de compostos fenólicos de erythrina velutina willd. por espectrometria de massas associada às redes moleculares (molecular networking)

Abstract

The identification, characterization, and study of bioactive compounds can open doors to understanding numerous applications of interest for research. The arboreal species Erythrina velutina Willd., popularly known as “mulungu,” belonging to the Fabaceae family and the Papilionoideae subfamily, is distributed throughout the Brazilian Northeast. Its leaves, seeds, and mainly trunk bark are used in folk medicine in teas to treat sleep disorders and central nervous system (CNS) conditions. Previous works with the species relate its pharmacological, anxiolytic, and sedative properties, mainly to the presence of flavonoids and benzylisoquinoline alkaloids. Given the above, the study proposal aimed to characterize the phenolic compounds present in the leaves and seeds of the species collected in four different locations in the Seridó region of Rio Grande do Norte. Dereplication of the crude ethanol extract of seeds and leaves from different populations occurred with the aid of the GNPS (Global Natural Product Social Molecular Networking) platform, based on mass data and fragmentation patterns obtained by analysis by liquid chromatography coupled with mass spectrometry (LC-MS), which led to the formation of a molecular network that presented clusters attributed to phenolic compounds. A total of 136 compounds were annotated, being 32 flavonoids, two coumarins, two anthocyanins, an aurone, and a chalcone annotated by the platform library. The analysis of unannotated metabolites indicated similarities in the fragmentation pattern related to the aglycones present in the sample with some variations present in the substituents. Principal component analysis (PCA) for the substances noted, and present in samples from different populations of E. velutina made it possible to evidence which compounds allow the differentiation of the studied organs, seeds and leaves. In addition, the PCA analysis for the seed samples allowed to evidence the separation of the samples according to the collection region. Complementary methodologies were also developed and standardized for the analysis of metabolites by gas chromatography, which allowed the identification of different fatty acids such as palmitic, linoleic, oleic and stearic acids present in Erythrina seeds, through the esterification reaction, as well as other substances, such as phytosterols, silylated fatty acids and alkaloids, by silylation reaction with a derivatizing agent BSTFA. Thus, this work contributes to a greater understanding of the profile of phenolic compounds present in E. velutina and standardizing techniques that may contribute to the knowledge of the metabolome of this species in the future.