The ERG6 gene is crucial for the biosynthesis of ergosterol, a key component of yeast cell membranes. Our study examines the impact of ERG6 gene deletion on the membrane composition and physicochemical properties of the pathogenic yeast Candida glabrata. Specifically, we investigated changes in selected sterol content, phospholipid composition, transmembrane potential, and PDR16 gene activity. Sterol levels were measured using high-performance liquid chromatography, the phospholipid profile was analysed via thin-layer chromatography, transmembrane potential was assessed with fluorescence spectroscopy, and gene expression levels were determined by quantitative PCR. Our findings revealed a depletion of ergosterol, increased zymosterol and eburicol content, an increased phosphatidylcholine and a reduced phosphatidylethanolamine content in the Δerg6 strain compared to the wt. Additionally, the Δerg6 strain exhibited membrane hyperpolarization without changes in PDR16 expression. Furthermore, the Δerg6 strain showed increased sensitivity to the antifungals myriocin and aureobasidine A. These results suggest that ERG6 gene deletion leads to significant alterations in membrane composition and may activates an alternative ergosterol synthesis pathway in the C. glabrata Δerg6 deletion mutant.

Drug delivery by dendron-based nanoparticles is widely studied due to their ability to encapsulate or bind different ligands. For medical purposes, it is necessary (even if not sufficient) for these nanostructures to be compatible with blood. We studied the interaction of amphiphilic dendrons with blood samples from healthy volunteers using standard laboratory methods and rheological measurements. We did not observe clinically relevant abnormalities, but we found a concentration-dependent increase in whole blood viscosity, higher in males, presumably due to the formation of aggregates. To characterize the nature of the interactions among blood components and dendrons, we performed experiments on the liposomes and exosomes as models of biological membranes. Based on results obtained using diverse biophysical methods, we conclude that the interactions were of electrostatic nature. Overall, we have confirmed a concentration-dependent effect of dendrons on membrane systems, while the effect of generation was ambiguous. At higher dendron concentrations, the structure of membranes became disturbed, and membranes were prone to forming bigger aggregates, as visualized by SEM. This might have implications for blood flow disturbances when used in vivo. We propose to introduce blood viscosity measurements in early stages of investigation as they can help to optimize drug-like properties of potential drug carriers.

The rising global incidence of Candida parapsilosis infections is increasingly complicated by antifungal resistance, resulting in frequent therapeutic failure. This study investigated the potential of the natural compound catechin to enhance the efficacy of fluconazole through synergistic interaction. We evaluated the susceptibility of C. parapsilosis clinical isolates and a reference strain to combinations of catechin and fluconazole using standardized microbiological assays and molecular techniques. In vivo efficacy was assessed using the Galleria mellonella infection model. Mechanistic studies included the measurement of intracellular reactive oxygen species (ROS) production and plasma membrane permeability. Catechin alone caused growth retardation in all strains. However, the combination of catechin and fluconazole resulted in complete growth inhibition of the reference strain and significant growth reduction in azole-resistant clinical isolates. While the combination slightly increased intracellular ROS production, no significant changes in plasma membrane permeability or membrane potential were observed. Notably, catechin induced the expression of the resistance-associated genes CpTAC1 and CpCDR1B in resistant isolates. In vivo experiments demonstrated that catechin significantly reduced mortality in G. mellonella larvae infected with C. parapsilosis. These findings suggest that catechin is a promising candidate for developing synergistic antifungal therapies against resistant Candida species.