Cross-linking of dithiols by mitomycin C.

Area of Science:

• Medicinal Chemistry
• Organic Chemistry
• Biochemistry

Background:

• Antitumor drug mitomycin C (MMC) is activated by reduction to a bis-electrophile.
• Dithiols are known to activate MMC through reduction.

Purpose of the Study:

• To investigate the reaction products of mitomycin C with dithiols.
• To elucidate the mechanism of S,S'-cross-link formation between MMC and dithiols.
• To explore potential interactions with dithiol-containing proteins.

Main Methods:

• Characterization of adducts using UV, HRMS, CD, and NMR spectroscopy.
• Analysis of reaction kinetics and product distribution based on dithiol concentration.
• Investigation of unexpected intermediates and byproducts.

Main Results:

• Dithiols, after activating MMC, are bis-alkylated to form S,S'-cross-links as major products.
• Characterization of diastereomeric adducts formed with 1,3-propanedithiol.
• Identification of multiple cross-links with dithiothreitol and dihydrolipoic acid, indicating complex reaction pathways.
• Observed dependence of cross-link formation on dithiol concentration suggests a second reduction step.

Conclusions:

• Dithiols play a dual role in MMC activation and subsequent cross-linking.
• The reaction mechanism involves a second dithiol-mediated reduction prior to bis-alkylation.
• Unexpected intermediates and mitosene derivatives suggest complex reaction pathways.
• Findings have implications for understanding MMC's interaction with biological dithiol-containing molecules.