Sonochemically induced covalent binding of calf thymus DNA by aziridinylquinones.

Sonolysis of argon- or oxygen-containing samples in the presence of calf thymus DNA and the diaziridinylquinones 2,5-bis-aziridin-1-yl-3,6-dichloro-1,4-benzoquinone (AZClQ) and 2,5-bis(carboethoxyamino)-3,6-diaziridinyl-1,4-benzoquinone (AZQ) produced quinone-DNA covalent adducts at pH 5.5 and to a much lesser extent at pH 7.4. The corresponding semiquinone derivatives are detected using EPR spectroscopy after sonolysis of argon-saturated solutions at pH 7.4. The amount of covalent adducts decreases with addition of SOD, indicating a role of superoxide in this process. Addition of oxygen to the purging gas decreased but did not eliminate this covalent adduct. Thus this work suggests a possible synergism between bioreductive quinones and ultrasound in antitumor therapies based on alkylating quinone-DNA adduct formation with potential applications to both hypoxic and normally oxygenated conditions.