Enzyme-induced aziridine formation by isolated hepatocytes.

Area of Science:

• Biochemistry
• Medicinal Chemistry
• Toxicology

Background:

• Naphthoquinone derivatives are investigated for their biological activities.
• Understanding the metabolic fate of xenobiotics in hepatocytes is crucial for drug development and toxicology.
• The role of cellular glutathione in xenobiotic metabolism requires further elucidation.

Purpose of the Study:

• To investigate the metabolic transformation of 2-bromoethylaminonaphthoquinone in isolated rat hepatocytes.
• To explore the metabolic pathway of 4-chlorobutylaminonaphthoquinone under similar conditions.
• To assess the impact of these compounds on cellular glutathione levels.

Main Methods:

• Incubation of 2-bromoethylaminonaphthoquinone and 4-chlorobutylaminonaphthoquinone with isolated rat hepatocytes.
• Chemical analysis to identify metabolic products.
• Quantification of cellular glutathione (GSH) levels.

Main Results:

• 2-bromoethylaminonaphthoquinone, chemically inert in buffer, was converted to aziridinylnaphthoquinone by hepatocytes.
• 4-chlorobutylaminonaphthoquinone underwent cyclization to form pyrrolidinylnaphthoquinone in the presence of hepatocytes.
• Both reactions led to a significant decrease in cellular glutathione (GSH).

Conclusions:

• Hepatocytes facilitate the cyclization of haloalkylaminonaphthoquinones, forming reactive aziridine and pyrrolidine intermediates.
• The observed decrease in cellular GSH suggests its involvement in detoxifying these naphthoquinone derivatives or their metabolites.
• These findings highlight the potential bioactivation of such compounds within the liver and their interaction with cellular defense mechanisms.