Potencial bioativo dos extratos de Eugenia luschnathiana (pitomba-da-bahia) : perfil fitoquímico, atividade antifúngica e avaliação da toxicidade

Abstract

Introduction: The therapeutic options available for managing patients with fungal infections, including those affecting the oral cavity, are limited by adverse effects and the emergence of resistant pathogens. Vulnerable populations, such as hospitalized or immunosuppressed individuals, are most affected by these infections. Advances in developing new effective and less toxic medications are crucial for treating fungal infections. Objective: To investigate the phytochemical profile, antifungal activity of the essential oil (EO), and crude ethanolic extract (CEE) obtained from Eugenia luschnathiana and perform toxicological characterization. Methodology: Determination of the phytochemical profile using Gas Chromatography-Mass Spectrometry (GC-MS) and 1H Nuclear Magnetic Resonance (NMR); determination of the Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) against reference strains (C. albicans ATCC 76645 e C. albicans ATCC 90028) and clinical isolates of Candida from patients undergoing oncological treatment; evaluation of potential mechanisms of action; evaluation of activity on fungal biofilm; evaluation of cytotoxic effect on human keratinocytes of the HaCat lineage by the MTT method; determination of lethality for Artemia salina larvae. Results: The predominant compounds in the essential oil, identified by GC-MS, belong to the sesquiterpenes class, with β - Cariofileno being the major compound. In the crude ethanolic extract, the 1H NMR spectrum identified aliphatic, osidic, and aromatic compounds. A phytochemical examination showed the presence of tannins and flavonoids. From the assays conducted, the essential oil, at the tested concentrations, did not show antifungal activity. The ethanolic extract showed fungicidal activity, with MIC and MFC ranging from 1.95 μg/mL to 3.90 μg/mL for the tested strains, possibly acting on the structures of the fungal cell wall. At a low concentration (19.5 μg/mL), the ethanolic extract inhibited 62.78% of the biofilm of Candida albicans. The ethanolic extract showed an inhibition of less than 25% on keratinocytes at concentrations lower than the MICx20 (39 μg/mL) and an Lethal Concentration 50 (LC50) for A. salina of 142.4 μg/mL Conclusion: The CEE exhibited very strong antifungal activity, with a probable action on the cell wall, effect on biofilm, and a toxicity profile compatible with further investigations. The data obtained from this study may stimulate the development of new antifungal medications for treating candidiasis with possible new mechanisms of action, expanding the current arsenal of antifungals.