Desenvolvimento de chalconas e derivados pirimidínicos como potenciais agentes antibacterianos e antioxidantes

Abstract

Chalcones, belonging to the flavonoid class, arouse great scientific interest due to their diverse biological activities and the possibility of structural modifications. These modifications may involve the introduction of various substituents to optimize their properties or their transformation into new classes of compounds through specific chemical reactions. The synthesis of chalcones is relatively simple, and their characterization is greatly facilitated by Nuclear Magnetic Resonance (NMR) spectroscopy. The conversion of chalcones into aminopyrimidines by reaction with guanidine has proven to be a promising approach for biological applications, as it alters essential physical properties such as lipophilicity. In this study, four chalcones were synthesized and subsequently converted into pyrimidines, whose antioxidant activity was evaluated by the DPPH radical-scavenging method and the phosphomolybdenum complex reduction assay. The results demonstrated that the pyrimidines exhibited greater antioxidant activity compared to their chalcone precursors, with the compounds bearing methoxy (–OCH3) and dimethylamino (–N(CH3)2) groups showing the highest antioxidant indices. Moreover, the compounds were tested against Staphylococcus aureus and Pseudomonas aeruginosa. In the case of S. aureus (a Gram-positive bacterium), it was observed that the presence of electron-donating substituents favored intracellular interaction, contributing to inhibition of bacterial growth. In contrast, for P. aeruginosa (a Gram-negative bacterium), the lipophilicity of the compounds influenced their permeability through the lipopolysaccharide-rich outer membrane, with the chalcone lacking electron-donating groups standing out. Thus, the results indicate that the conversion of chalcones into pyrimidines can enhance both antioxidant and antimicrobial activities. Furthermore, they highlight the need for structural adjustments to maximize the efficacy of these compounds against specific biological targets, reinforcing the importance of future studies aimed at optimizing their properties.