Avaliação da atividade antifúngica do linalol sobre Candida albicans de secreções vulvovaginais

• Ano de defesa: 2023
• Autor(a) principal: Medeiros, Cássio Ilan Soares
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal da Paraíba; Brasil; Farmacologia; Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos; UFPB
• Palavras-chave em Português: Biofilme; Candidíase; Docking molecular; Mecanismo de ação; Resistência antifúngica; Sinergismo; Biofilm; Candidiasis; Molecular docking; Mechanism of action; Antifungal resistance; Synergism; CNPQ::CIENCIAS BIOLOGICAS::FARMACOLOGIA
• Link de acesso: https://repositorio.ufpb.br/jspui/handle/123456789/29343

Candida albicans is the most commonly isolated opportunistic fungal pathogen in humans, accounting for more than 90% of cases of serious fungal infections. It is also the most frequent cause of vulvovaginal candidiasis (VVC), which accounts for 70-90% of vulvovaginitis cases. The widespread use of a limited number of antifungal agents, particularly azole drugs such as fluconazole, has led to the development of microbial resistance in the treatment of Candida infections, a problem of increasing importance. Therefore, there is an urgent need for new antifungal agents for the efficient management of these infections. Therefore, the researches about the active constituents of natural products can be a promising alternative to this problem. In this sense, it stands out the linalool, molecule with several bioactivities and originated from several plants such as Lavandula angustifolia, Lippia alba, Coriandrum sativum L, among others. However, there are not many studies in the literature about the mechanism of action of linalool on fungal cells, toxicity, synergism with licensed antifungal drugs, action on biofilm and the stability of the receptor-ligand complex. Therefore, this study aimed to investigate the pharmacological potential of linalool against C. albicans strains from vulvovaginal secretions. For this purpose, in vitro microdilution techniques were applied to determine the minimum inhibitory and fungicidal concentration (MIC and MFC), as well as assays with sorbitol and ergosterol to verify mechanisms of action on the fungal cell wall and membrane respectively, besides the association study (checkerboard). To evaluate biofilm formation and the interference of linalool in this process, the crystal violet assay was performed. In addition, the linalool was submitted to online softwares (pkCSM and Osiris) to perform the prediction of parameters of druggability and toxicity. Furthermore, molecular docking was performed in AutoDock 4.2 with the proteins involved with the synthesis and maintenance of the cell wall and cell membrane of C. albicans (1,3-β-glucan synthase, lanosterol 14α-demethylase and Δ14- sterol reductase), and finally molecular dynamics (MD) trajectory analysis was performed in GROMACS 2022.3 of the complex (1,3-β-glucan synthase - linalool) with 30ns of simulation. The main results of this study indicated that linalool was bioactive against fluconazole-resistant C. albicans strains with an MIC50 of 64µg/mL and fungicidal in nature. Furthermore, the increase in the MIC of linalool in the presence of sorbitol and ergosterol revealed that this molecule possibly affects the integrity of the wall and plasma membrane of C. albicans. The linalool associated with fluconazole, exhibited synergistic effect against strains of C. albicans, but had an indifferent effect when associated with nystatin. Linalool also interfered in the biofilm formation process of C. albicans, reducing its formation by 74.65%. In silico pharmacokinetic analysis showed that linalool has significant theoretical oral bioavailability, low toxic potential and high similarity to licensed drugs. Additionally, linalool chemically interacted via hydrogen bonds, van der Waals, and among others; with key enzymes of C. albicans wall and plasma membrane biosynthesis with best interaction with 1,3-β-glucan synthase (∆G = -6.0kcal/mol) in which they formed a stable receptor-ligand complex over 30ns of simulation, indicating likely enzyme inhibition. Taken together, the findings of this study indicated that linalool probably causes damage to the cell wall and plasma membrane of C. albicans, directly or possibly by interaction with important enzymes involved in the biosynthesis of these fungal structures, acted synergistically with fluconazole, significantly reduced biofilm formation, and showed low toxicological potential in silico.