Study of trans-cyclopropylbis (diketopiperazine) and chelating agents related to ICRF 159. Cytotoxicity, mutagenicity, and effects on scheduled and unscheduled DNA synthesis.

The cytotoxicity, mutagenicity, and DNA damaging potential of trans-cyclopropylbis (diketopiperazine) (3) and chelating agents related to ICRF 159 (1) were examined as a function of concentration and duration of exposure in the Chinese hamster cell line V79A. At a concentration of 10(-3) M, 1 and the trans-cyclopropanediamine tetraacid 8 and ester 7 proved to be cytotoxic and mutagenic. The trans-cyclopropyl analogue 3 of ICRF 159 and acyclic tetraacid 6 were less cytotoxic at all concentrations; analogue 3 exhibited no mutagenic activity at any of the concentrations tested. Compounds 1, 7, and 8, at lethal concentrations, exhibited significantly different mutation frequencies with 7 being sixfold more mutagenic than 8 at the same molar concentration. At 10(-3) M compounds 8 was several times more effective blocking DNA replication than other analogues but did not induce unscheduled DNA synthesis as did 1,3, and 6. With the exception of 8, there was an excellent correlation between mutagenesis and the induction of unscheduled DNA synthesis.