A group of arylalkyl isothiocyanates were tested for their abilities to inh
ibit tumorigenicity and DNA methylation induced by the esophageal-specific
carcinogen, N-nitrosomethylbenzylamine (NMBA) in the F344 rat esophagus. Ph
enylpropyl isothiocyanate (PPITC) was more potent than either phenylethyl i
sothiocyanate (PEITC) or benzyl isothiocyanate (BITC). Phenylbutyl isothioc
yanate (PBITC), however, had a lesser inhibitory effect on esophageal tumor
igenesis, and phenylhexyl isothiocyanate (PHITC) actually enhanced esophage
al tumorigenesis. Thus, the two- and three-carbon isothiocyanates were more
effective inhibitors of NMBA-esophageal carcinogenesis than the longer cha
in isothiocyanates. The effects of the isothiocyanates on tumorigenesis wer
e well correlated as to their effects on DNA adduct formation. The most lik
ely mechanism of inhibition of tumorigenesis by these isothiocyanates is vi
a inhibition of the cytochrome P450 enzymes responsible for the metabolic a
ctivation of NMBA in rat esophagus. A freeze-dried strawberry preparation w
as also evaluated for its ability to inhibit NMBA-esophageal tumorigenesis.
It proved to be an effective inhibitor, although not as potent as either P
EITC or PPITC. The inhibitory effect of the berries could not be attributed
solely to the content of the chemopreventive agent, ellagic acid, in the b
erries.