Exploring therapeutic targets for cryptococcosis: in silico and in vitro testing for isocitrate lyase (ICL1)...

Area of Science:

• Mycology
• Biochemistry
• Drug Discovery

Background:

• Cryptococcosis is a severe fungal infection caused by Cryptococcus species.
• Current antifungal treatments for cryptococcosis face challenges including toxicity, long treatment durations, and drug resistance.
• Isocitrate lyase (ICL1), an enzyme in the glyoxylate cycle, presents a potential target for novel antifungal therapies.

Purpose of the Study:

• To identify inhibitors of isocitrate lyase (ICL1) from FDA-approved drugs for potential treatment of cryptococcosis.
• To evaluate the in silico and in vitro efficacy of identified compounds against Cryptococcus species.

Main Methods:

• Virtual screening of FDA-approved drug libraries to identify potential ICL1 inhibitors.
• Molecular dynamics simulations and binding free energy calculations to assess drug-target interactions.
• In vitro antifungal assays to determine minimum inhibitory concentrations (MICs) against Cryptococcus neoformans and Cryptococcus gattii strains.

Main Results:

• Virtual screening identified five candidate drugs, with isoniazid showing strong binding affinity and structural stability through interactions with Trp97.
• In vitro testing confirmed isoniazid's antifungal activity, but with high MIC values indicating strain-dependent susceptibility and limited direct efficacy at high concentrations.
• Isoniazid demonstrated inhibition of cryptococcal biofilm formation, suggesting a potential dual mechanism of action.

Conclusions:

• Isoniazid exhibits potential as an antifungal agent against Cryptococcus by targeting ICL1 and inhibiting biofilm formation.
• The study highlights the promise of drug repurposing and combination therapies for cryptococcosis, despite high MIC values for isoniazid.
• Further investigation into isoniazid's synergistic effects with existing antifungals is warranted for cryptococcosis treatment.