Resumo:
Natural products, especially medicinal plants, represent a significant source of bioactive compounds with considerable potential for the development of new synthetic substances due to their rich diversity of secondary metabolites. The genus Kielmeyera (Calophyllaceae), widely distributed in Brazil and known for its content of xanthones, coumarins, and triterpenes, stands out for its diverse biological activities and ethnopharmacological relevance. In this context, the present study aimed to compare the metabolic profiles of Kielmeyera argentea, K. neglecta, and K. reticulata species at different times of the year, using Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy and chemometric tools as analytical approaches for seasonal characterization. The species were collected from the restinga areas of the Parque Metropolitano do Abaeté in Salvador/BA, and from the municipality of Camaçari/BA, in October 2021, February, May, and July 2022. Extracts were obtained by ultrasonication using hexane, ethyl acetate, and methanol as solvents and analyzed on an Agilent INOVA 500 MHz spectrometer. The spectra were aligned using the Icoshift algorithm (MatLab R2017a) and subjected to Principal Component Analysis (PCA) in Pirouette® 4.5, after autoscaling treatment. Chemometric analyses revealed that the main separation among samples was associated with the plant parts analyzed – leaves and stems – indicating chemical differences related to tissue type. Conversely, seasonality did not significantly affect the metabolic profiles of the studied species, although slight variations were observed for K. argentea in ethyl acetate extracts. Overall, the results demonstrated stability in metabolite production throughout the year, suggesting that genetic and structural factors exert a greater influence on the metabolism of Kielmeyera species than seasonal environmental conditions. The combination of NMR and chemometrics proved to be an efficient strategy for exploring complex metabolic data, contributing to the chemical and biological knowledge of the genus Kielmeyera, as well as to the training of qualified human resources in the fields of Organic Chemistry, NMR, and Chemometrics.