Strong antimutagenic effect of caffeine on 9-aminoacridine-induced frameshift mutagenesis in Escherichia coli K12.

Caffeine, present at a concentration of 3 mg/ml during treatment with 100 microM 9-aminoacridine (9AA) of wild-type Escherichia coli K12, caused a decrease in the yield of frameshift reversions of more than three orders of magnitude. Antimutagenesis of caffeine was shown to be due to partial inhibition of induction by 9AA of frameshift replication errors, resulting in an increased efficiency of mismatch repair of the pre-mutations produced under these conditions.