Identification and evaluation of novel drug targets against the human fungal pathogen Aspergillus fumigatus with elaboration on the possible role of RNA-binding protein

Bakground: Aspergillus fumigatus is an airborne opportunistic fungal pathogen that can cause fatal infections in immunocompromised patients. Although the current anti-fungal therapies are relatively efficient, some issues such as drug toxicity, drug interactions, and the emergence of drug-resistant fungi have promoted the intense research toward finding the novel drug targets

Methods: In search of new antifungal drug targets, we have used a bioinformatics approach to identify novel drug targets. We compared the whole proteome of this organism with yeast Saccharomyces cerevisiae to come up with 153 specific proteins. Further screening of these proteins revealed 50 potential molecular targets in A. fumigatus. Amongst them, RNA-binding protein [RBP] was selected for further examination. The aspergillus fumigatus RBP [AfuRBP], as a peptidylprolyl isomerase, was evaluated by homology modeling and bioinformatics tools. RBP-deficient mutant strains of A. fumigatus were generated and characterized. Furthermore, the susceptibility of these strains to known peptidylprolyl isomerase inhibitors was assessed

Results: AfuRBP-deficient mutants demonstrated a normal growth phenotype. MIC assay results using inhibitors of peptidylprolyl isomerase confirmed a higher sensitivity of these mutants compared to the wild type

Conclusion: Our bioinformatics approach revealed a number of fungal-specific proteins that may be considered as new targets for drug discovery purposes. Peptidylprolyl isomerase, as a possible drug target, was evaluated against two potential inhibitors and the promising results were investigated mechanistically. Future studies would confirm the impact of such target on the antifungal discovery investigations

Synthesis and antimycobacterial activity of some triazole derivatives - new route to functionalized triazolopyridazines

A series of cyclic analogues of bioactive thiosemicarbazide derivatives have been synthesized as potential antimycobacterial agents. The 4-amino-1,2,4-triazole-5-thione analogues [Ia-f] were prepared by heating a mixture of thiocarbohydrzide and appropriate carboxylic acids. Reaction of thiocarbohydrazide with gamma-ketoesters in the presence of sodium methoxide furnished triazolopyridazine derivatives IIa-b. Finally, condensation of 4-amino-1,2,4-triazole-5-thione with some aldehydes gave Schiff bases IIIa-e. After characterization by different spectroscopic and analytical methods, the derivatives were tested for their inhibitory activity against Mycobacterium bovis BCG. Among the derivatives, compound Ib proved to be the most potent derivatives with MIC value of 31.25 microg/mL. Given the fact that 4-amino-1,2,4-triazole-5-thiones Ia-f were the most active derivatives, it could be suggested that this group of derivatives have the potential to be considered as lead compounds for future optimization efforts

Antifungal indole and pyrrolidine-2,4-dione derivative peptidomimetic lead design based on in silico study of bioactive peptide families

The rise of opportunistic fungal infections highlights the need for development of new antimicrobial agents. Antimicrobial Peptides [AMPs] and Antifungal Peptides [AFPs] are among the agents with minimal resistance being developed against them, therefore they can be used as structural templates for design of new antimicrobial agents. In the present study four antifungal peptidomimetic structures named C[1] to C[4] were designed based on plant defensin of Pisum sativum. Minimum inhibitory concentrations [MICs] for these structures were determined against Aspergillus niger N402, Candida albicans ATCC 10231, and Saccharomyces cerevisiae PTCC 5052. C[1] and C[2] showed more potent antifungal activity against these fungal strains compared to C[3] and C[4]. The structure C[2] demonstrated a potent antifungal activity among them and could be used as a template for future study on antifungal peptidomemetics design. Sequences alignments led to identifying antifungal decapeptide [KTCENLADTY] named KTC-Y, which its MIC was determined on fungal protoplast showing 25 [micro g/ml] against Aspergillus fumigatus Af293. The present approach to reach the antifungal molecules seems to be a powerful approach in design of bioactive agents based on AMP mimetic identification

Synthesis and antimycobacterial activity of symmetric thiocarbohydrazone derivatives against Mycobacterium bovis BCG

In this work, we reported the synthesis and evaluation of antimycobacterial and antifungal activity of a series of thiocarbohydrazone derivatives which are thiacetazone congeners. The target compounds were synthesized in superior yields by reacting thiocarbohydrazide with different aromatic aldehydes and methyl ketones. Compounds 8, 19 and 25 were found to be the most potent derivatives, exhibiting acceptable activity against Mycobacterium bovis BCG compared to thiacetazone and ethambutol as reference substances. Compounds 8, 15 and 25 exhibited the highest activity against Candida albicans. The most active compounds had a completely different aromatic ring system with various electronic, steric and lipophilic natures. This is understandable in light of the fact that carbohydrazone derivatives must undergo a metabolic activation step before exerting their anti-TB activity and different SAR rules govern each one of these two processes