In this review, retinol, chlorophyllin, and N-acetylcysteine are exami
ned and compared with regard to their antimutagenic activity against s
ome promutagens and a group of direct-acting alkylating agents. The pr
omutagens included aflatoxin B-1, certain polycyclic aromatic hydrocar
bons (e.g., benzo[a]pyrene), and certain heterocyclic amines (e.g., fo
od pyrolysates). Results of antimutagenicity testing selected from dat
a surveyed in the published literature are displayed graphically as ac
tivity profiles of antimutagens showing both the doses tested and the
extent of inhibition or enhancement of mutagenic activity. All three a
ntimutagens are discussed in terms of their putative mechanisms of act
ion in vitro and in vivo with emphasis on the xenobiotic metabolizing
enzyme systems.