Caracterização química e avaliação da atividade antifúngica de extratos e frações dos galhos de Microlicia parviflora

Abstract

Fungal infections represent a significant global public health problem, with growing concern due to the emergence of multidrug-resistant strains, particularly from the Candida genus. In this context, the Cerrado biome, recognized for its high biodiversity, harbors plant species with pharmacological potential that are promising sources of specialized metabolites with antifungal activity. Therefore, this study aimed to investigate the antifungal potential of extracts and partitions obtained from the branches of Microlicia parviflora (Melastomataceae), a native species of the Brazilian Cerrado, against Candida species, and to chemically characterize the compounds present in the most active samples. The hexanic (HE) and ethanolic (EE) extracts were obtained by maceration, and the EE was subsequently fractionated by liquid-liquid extraction, yielding the dichloromethane (DP), ethyl acetate (EAP), n-butanol (BP), and aqueous (AqP) partitions. Phytochemical screening by TLC indicated the presence of flavonoids, tannins, terpenes, and steroids. The antifungal activity was evaluated using the broth microdilution method to determine the Minimum Inhibitory Concentration (MIC) against Candida albicans, C. tropicalis, C. glabrata, and the multidrug-resistant C. auris. The EE and BP showed the best results, notably the EE against C. glabrata (MIC = 1.46 µg mL−1) and C. auris (MIC = 2.93 µg mL−1), and the BP against C. auris (MIC = 11.72 µg mL−1), being the positive control (amphotericin B) with expected MIC between 0.25 and 2.0 µg mL⁻¹. HPLC-ESI-MS/MS analyzed the most active samples (EE and BP) in negative mode. Nineteen compounds were annotated, predominantly belonging to the classes of phenolics (gallic acid, ellagic acid, daucic acid), flavonoids (epicatechin, glycosylated derivatives of quercetin), and hydrolyzable tannins (pedunculagina and casuarinin). The results demonstrate that M. parviflora is a source of specialized metabolites, mainly phenolic compounds, with significant antifungal activity against Candida species, including the emerging and multidrug-resistant C. auris. This study contributes to the valorization of the Cerrado's biodiversity and highlights the potential of this species for the development of future antifungal agents.