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Background: This study was performed to determine antifungal activity of silver nanoparticles (nano-Ag) compared to voriconazole on clinical and standard strains of Aspergillus fumigatus.
Materials and Methods: Inhibitory potency of nano-Ag was determined using microtiter broth dilution method. Susceptibility tests were performed against A. fumigatus isolated from BAL (bronchoalveolar lavage) of patients who suffered from respiratory problems and compared with the strain (ATCC: 204305) by broth dilution antifungal susceptibility test of filamentous fungi approved by the Clinical and Laboratory Standards Institute M38-A. In addition, cytotoxicity effect of silver nanoparticles was studied on epithelial cell line by MTT assay.
Results: From 60 BAL samples the following strains were isolated; A. flavus (n=21), A. niger (n=3), and A. fumigatus (n=1). The minimum inhibitory concentration (MIC₉₀) values of nano-Ag were 0.25 and 0.5 μg.mL^-1 for standard strain and clinical isolates respectively. The  Minimum Fungicidal Concentration (MFC) values of nano-Ag were 0.5 and 1 μg.mL^-1for standard strain and clinical isolates respectively. MIC90 values of voriconazole were 0.125 and 0.25 μg.mL^-1 for standard strain and clinical isolate respectively. The MFC values of voriconazole were 0.25 and 0 μg.mL^-1 for standard strain and clinical isolates respectively. Silver nanoparticles exhibited low cytotoxicity in 0.25 μg.mL^-1 concentration.
Conclusion: Our results showed high antifungal activity of silver nanoparticles against Aspergillus isolates. Furthermore, the availability of a wide form of nano-Ag structures can be considered as novel agents to decrease fungal burden in medical application.

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Backgrounds: Aspergillus fumigatus is a pathogen responsible for invasive aspergillosis and the main leading cause of death in immunosuppressed individuals. The present study aimed to evaluate the impact of eugenol-loaded chitosan nanoparticles on the expression of CYP51a and CYP51b, two well-known genes responsible for triazole drug resistance in A. fumigatus.
Materials & Methods: The minimum inhibitory concentration (MIC) of eugenol-loaded chitosan nanoparticles, chitosan, eugenol, and itraconazole was determined based on the Clinical and Laboratory Standards Institute M38-E3 method at concentrations of 4.6-2400, 11.7-12000, 2-2048, and 1-256 μg/mL, respectively. The expression of CYP51A and CYP51B was evaluated in A. fumigatus exposed to 0.5, 1, and 2× of MIC concentration of NPs and itraconazole using the real-time polymerase chain reaction.
Findings: The obtained results showed that eugenol-loaded chitosan nanoparticles sucessfully reduced A. fumigatus fungal growth at 300 μg/mL concentration. MIC of chitosan, eugenol, and itraconazole was measured to be 6000, 256, and 4 μg/mL, respectively. The results of real-time PCR also revealed that eugenol-loaded chitosan nanoparticles increased the expression of both CYP51A and CYP51B in a dose-dependent manner. The expression of fungal CYP51A and CYP51B at mRNA level was significantly increased 1.26, 1.93, and 3.1-fold as well as 1.2, 2.1, and 2.4-fold at concentrations of 150, 300, and 600 μg/mL, respectively (p<.05). However, it seems that the prepared nanoparticles had a lower impact on the expression of these genes compared to itraconazole.
Conclusion: Overall, these findings suggest that the treatment of A. fumigatus with eugenol-chitosan nanoparticles could increase the expression of the CYP51 gene, suggesting the anti-fungal property of these nanoparticles.

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Backgrounds: Allium cepa L. as a traditional medicine is a rich source of beneficial bioactive metabolites. In the present study, the effect of A. cepa ethanolic extract (EAC) was studied on Aspergillus fumigatus growth, ergosterol synthesis, gliotoxin production, and gliP gene expression.
Materials & Methods: The minimum inhibitory concentration (MIC) of EAC (125-4000 µg/mL) was determined against A. fumigatus isolates according to Clinical and Laboratory Standards Institute (CLSI) guidelines (M-38). Protease activity, gliotoxin production, cell membrane ergosterol content, ultrastructure, and gliP gene expression were evaluated in the fungus exposed to 0.5× MIC concentrations of EAC (1000 μg/mL) and fluconazole (FCZ: 64 μg/mL).
Findings: Ergosterol content was significantly reduced to 0.53 and 0.45 µg/mg in FCZ- and EAC-treated fungal cells, respectively (p< .001). The protease activity was significantly inhibited in both EAC- and FCZ-treated groups. The gliotoxin production was inhibited by 51.55 and 68.75% in the treated groups with FCZ and EAC, respectively. The expression of gliP in both EAC- and FCZ-treated A. fumigatus groups was significantly reduced by 0.40 and 0.53-fold, respectively (p< .05).
Conclusion: This study finding revealed that A. cepa ethanolic extract (EAC) effectively suppressed the growth and virulence factors of A. fumigatus, which could be attributed in part to its bioactive metabolites. Further studies are recommended to isolate and identify these metabolites as potential candidates for the development of antifungal drugs.

 

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The present study aimed to isolate the steroids and fatty acids from the liver of the Persian Gulf spot tail shark Carcharhinus sorrah and to assess their antifungal activity. Extraction was done by methanol 70% and then, the lipids were separated through column chromatography with silica gel. Identification of the extracted lipids was done by thin layer chromatography and gas chromatography coupled with mass spectrometry. Then, antifungal activity of the steroids was investigated through determining the minimum inhibition concentration and minimum fungicidal concentration by tubular dilution method against Aspergillus fumigatus and Candida albicans. Identification of the extracted compounds by GC-MS confirmed the presence of these steroids in the shark liver. The identified steroids included compounds of Y-Sitosterol, Desmosterol and Squalene, which showed different results regarding the growth inhibition and fungicidal effects against the microorganisms at different experimental doses. Desmosterol and Squalene at minimum concentration induced the highest inhibitory effect on the fungus but Y-Sitosterol induced the highest inhibitory effect on the yeast. Squalene showed fungicidal effect only on the fungus and totally, A. fumigatus was more sensitive to the antimicrobial activity of the liver compounds than C.  albicans. In conclusion, promising results were found regarding the antimicrobial activity of the lipid compounds derived from Persian Gulf shark liver, revealing the importance of more comprehensive investigations of these natural compounds for the synthesis of biomedicines from the marine organisms.