Clarke C H, Shankel D M
Mol Gen Genet. 1977 Sep 9;154(3):335-6. doi: 10.1007/BF00571291.
In E. coli strain 91P containing the mutator gene mutT-, caffeine, spermine and quinacrine, but not guanosine, act as antimutagens, reducing the frequencies of mutation from ara- leads to Ara.