Optimization of Antifungal 1,5-Diaryl-Pyrazole Acetyl-CoA Synthetase Inhibitors

Area of Science:

• Medicinal Chemistry
• Biochemistry
• Drug Discovery

Background:

• Acetyl-CoA Synthetases (ACS) are crucial enzymes and potential drug targets for various diseases, including fungal infections.
• Broad-spectrum ACS inhibition has been limited to nucleoside-derived bisubstrate analogs like adenosine monophosphate (AMP) esters.
• The non-nucleoside inhibitor AR-12 demonstrated broad-spectrum antifungal activity against *Saccharomyces cerevisiae* ACS.

Purpose of the Study:

• To optimize the AR-12 scaffold for improved pharmacology and activity against ACS enzymes from human fungal pathogens (*Candida albicans*, *Cryptococcus neoformans*, *Aspergillus fumigatus*).
• To identify key structural features of diaryl pyrazoles responsible for ACS inhibition.
• To evaluate the binding mode and potential therapeutic advantages of optimized analogs.

Main Methods:

• Medicinal chemistry optimization of the AR-12 scaffold.
• Enzyme inhibition assays against fungal ACS enzymes.
• Molecular modeling and molecular dynamics simulations.
• Assessment of mammalian cytotoxicity and in vitro pharmacology.

Main Results:

• A series of diaryl pyrazole analogs with improved on-target activity against multiple fungal ACS enzymes were identified.
• Key substituents critical for ACS inhibition by this class of compounds were determined.
• Modeling suggests optimized analogs bind in the same active site region as alkyl-AMP esters.
• The most potent analog exhibited improved mammalian cytotoxicity and pharmacology compared to AR-12.

Conclusions:

• The optimized diaryl pyrazole scaffold represents a promising class of non-nucleoside ACS inhibitors with broad-spectrum antifungal potential.
• Structural modifications significantly enhance potency and selectivity against fungal ACS enzymes.
• Further optimization is necessary to develop a preclinical candidate with efficacy in animal models for treating fungal infections.