INHIBITION BY CHLOROPHYLLIN OF 2-AMINO-3-METHYLIMIDAZO[4,5-F]QUINOLINE-INDUCED TUMORIGENESIS IN THE MALE F344 RAT

This report describes a 1-year carcinogenicity bioassay in which male F344 rats received 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) by gav age 2-3 times per week throughout the first 35 weeks of study, while 0 .1% sodium/copper chlorophyllin (CHL) was given concomitantly in the d rinking water. The carcinogen dose was calculated to provide an averag e exposure of 4.2 mg IQ/rat per day, equivalent to that reported in a previous carcinogenicity study in which rats were given 0.03% IQ in th e diet. Adjusted for length of follow-up, inhibition was highly signif icant for total tumor burden (P < 0.001), and for specific sites was s ignificant in the small intestine and Zymbal's gland (P less than or e qual to 0.1), and in the liver (P < 0.01). In rats given CHL, the firs t onset of tumors in the Zymbal's gland was delayed from week 20 to 36 , but was shortened from week 31 to 26 in the skin (P < 0.05). These r esults support a chemopreventive role for CHL in several of the major target organs for IQ tumorigenesis in the rat, but raise concerns over possible deleterious effects in the skin .