DNA cleavage by 7-methylbenzopentathiepin: a simple analog of the antitumor antibiotic varacin.

Abstract The compound 7-methylbenzopentathiepin, a simple analog of the benzopentathiepin antitumor antibiotic varacin, was shown to be a potent thiol-dependent DNA-cleaving agent. Biological experiments previously suggested that DNA cleavage might play a role in the cytotoxicity of varacin; however, this is the first direct evidence that benzopentathiepins can cause DNA strand breaks under physiologically relevant conditions.