Chemical structure and genotoxicity: studies of the SOS chromotest.

Analyses of a data base consisting of 461 chemicals tested in the SOS chromotest with MULTICASE resulted in the development of an SAR model that displayed a highly significant concordance (87.3%) between experimental and predicted results of chemicals not included in the model. An analysis of the nature of the biophores and their modulators revealed that electrophilicity and structural features affecting: (a) accessibility of the electrophile to the nucleophilic site on the DNA; and (b) the bulkiness of the DNA adduct were factors determining the probability that a chemical would induce DNA error prone repair and if so the extent of this activity. Additional analyses indicated that there were significant mechanistic similarities between the SOS chromotest and mutations in Salmonella as determined in the standard ('Ames') assay.