| Congresso Brasileiro de Microbiologia 2023 | Resumo: 299-1 | ||||
Resumo:Invasive or non-invasive fungal infections caused by Candida albicans are a worldwide health problem. The antifungals available on the market are quite limited, so more efforts have been made in the search for new antifungals with low cytotoxicity. The objective of this work was to evaluate the combination of synthetic peptides (based on the γ-core domain of PvD1 defensin) with amphotericin B at different concentrations against the yeast C. albicans. We applied the checkerboard technique using different concentrations of amphotericin B and the synthetic peptides γ31-45PvD1++ and γ33-41PvD1++, against C. albicans, aiming to find combinations with synergistic interactions. Studies of mechanisms of action were performed with the aid of fluorescence microscopy and specific fluorophores for each mechanism, and transmission electron microscopy. Four combinations with activity were obtained, two combinations with additive effect: when we used 0.009 µM of γ33-41PvD1++ peptide and 13.23 µM of amphotericin B and when we used 0.019 µM of γ33-41PvD1++ peptide and 6.61 µM of amphotericin B. The other two interaction combinations showed a synergistic effect in the combination of the synthetic peptide γ31-45PvD1++ and amphotericin B, where the concentrations were 1.40 µM of γ31-45PvD1++ peptide and 0.004 µM of amphotericin B, and 0.70 µM of peptide γ31-45PvD1++ and 0.002 µM of amphotericin B. We proceeded to analyze the mechanism of action with combinations of synergistic effect, where it was possible to observe the loss of mitochondrial functionality, loss of cell wall integrity, DNA degradation and loss of viability in synergistic combinations. Through transmission electron microscopy, we observed that both synergistic combinations were able to cause damage to the plasma membrane and cell wall, causing leakage of intracellular wall components. In conclusion, this discovery demonstrates for the first time that the synergistic combinations found between the synthetic peptide γ31-45PvD1++ and amphotericin B have an antifungal effect against the yeast C.albicans, acting on the integrity of the plasma membrane and the cell wall, which can offer a new therapeutic alternative for the treatment of fungal diseases related to this microorganism. Palavras-chave: Action Mechanism, Synthetic Peptide, Synergism, Yeast Agência de fomento:Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) | |||||