Inhibition of DNA Adduct Formation and Mutagenic Action of 3‐Amino‐l‐methyl‐5H‐pyrido[4,3‐b]indole by Chlorophyllin‐chitosan in rpsL Transgenic Mice

We have studied the inhibitory effect of chlorophyllin‐chitosan (Chl‐Chi) complex, an insoluble form of chlorophyllin, on the DNA adduct formation and mutagenesis by a heterocyclic food mutagen‐carcinogen, 3‐amino‐l‐methyl‐5H‐pyrido[4,3‐b]indole (Trp‐P‐2), in mice carrying the E. coli rpsL gene as a mutagenesis reporter. Upon administration of a diet containing 0.002% or 0.01% Trp‐P‐2, DNA adducts were formed in various tissues in a dose‐dependent manner, with the maximum level observed in the liver. Addition of 3% Chl‐Chi to the diet reduced the Trp‐P‐2 adduct by up to 90%. The rpsL mutant frequencies increased significantly in both the liver and spleen upon administration of a 0.01% Trp‐P‐2 diet. Addition of Chl‐Chi to the diet decreased these induced mutant frequencies to the background level. No harmful effect of Chl‐Chi was detected during these experiments. The results show that Chl‐Chi may be a candidate chemopreventive agent against the genotoxic action of Trp‐P‐2, and possibly also other aromatic carcinogens in the diet.