Chromotest estimation of SOS functions as a screening method for antitumor platinum complexes

The chromotest which measures the induction of SOS functions in an Escherichia coli strain bearing the lacZ gene under the sfiA gene control was evaluated as a screening method for platinum complexes with antitumor activity. Four types of complexes were used: (a) those with two nitrogen ligands in cis position and chlorine or carboxylic acid as anionic ligand; (b) four nitrogen atoms surrounding platinum; (c) complexes involving sulphur and amino group of methionine; (d) complexes of tetravalent platinum. The trans-diaminodichloro complex was used as negative control. Groups (b) and (c) were inactive in the chromotest which correlated well with their absence of antitumor activity. Antitumor activity and a positive chromotest also correlated in group (d). In group (a), which includes complexes with well established antitumor activity, the chromotest separated complexes with fast and slow rate of hydrolysis. The results fitted well in the mutation induction test.