Rapid in vitro metabolic screen for antileprosy compounds

Area of Science:

• Microbiology
• Drug Discovery
• Biochemistry

Background:

• Leprosy remains a significant global health challenge, necessitating novel therapeutic agents.
• Rapid screening methods are crucial for accelerating the development of new antileprosy drugs.
• Intracellular adenosine triphosphate (ATP) levels can indicate microbial viability and response to antimicrobial agents.

Purpose of the Study:

• To assess the utility of measuring intracellular ATP decay in Mycobacterium leprae as a rapid in vitro method for identifying potential antileprosy drugs.
• To evaluate the sensitivity of this ATP-based assay to various antimicrobial agents with different modes of action.

Main Methods:

• Mycobacterium leprae, derived from nude mice, was cultured in axenic medium with or without antimicrobial agents for up to three weeks.
• Intracellular ATP levels were quantified using the firefly bioluminescence assay to measure ATP decay rates.

Main Results:

• Rifampin, clofazimine, and ethionamide significantly accelerated ATP decay compared to controls.
• Dapsone showed minimal activity, suggesting potential limitations for certain drug mechanisms.
• The assay demonstrated sensitivity to various active compounds including erythromycin, minocycline, and ciprofloxacin, while some agents like penicillins and isoniazid were inactive.

Conclusions:

• Intracellular ATP measurement in Mycobacterium leprae is a viable and rapid screening tool for potential antileprosy drug candidates.
• This method shows promise for evaluating new analogs of existing drugs, such as clofazimine.
• The ATP decay assay can identify compounds with diverse mechanisms of action, supporting its role in primary drug screening for leprosy.