Comparative carcinogenicity of 5-nitrothiophenes and 5-nitrofurans in rats.
We investigated the carcinogenicity of five 5-nitrothiophenes with heterocyclic substituents at the 2-position of the thiophene ring by feeding the chemicals to Sprague-Dawley rats and comparing the type and incidence of lesions with those appearing after exposure to two 5-nitrofurans. Benign and malignant mammary tumors and intestinal tract sarcomas were the most frequent lesions induced by 5-nitrothiophenes. 4-Bis(2-hydroxyethyl)amino-2-(5-nitro-2-thienyl)quinazoline caused a 100% incidence of mammary adenocarcinomas in 28 female rats at risk; it induced 3 benign and 5 malignant mammary tumors and 13 small intestine sarcomas in 20 male rats. A high incidence of similar lesions was observed in male and female rats fed the corresponding 5-nitrofuran analogue, 4-bis(2-hydroxyethyl)amino-2-(5-nitro-2-furyl)quinazoline. In marked contrast, 4 of 28 female rats receiving 4-bis(2-hydroxyethyl)amino-2-(2-thienyl)quinazoline, which lacks the nitro group at the 5-position on the thiophene ring, had solitary benign mammary tumors (P greater than 0.2). Additional 5-nitrothiophenes demonstrating significant oncogenic activity for female rats were 4-morpholino-2-(5-nitro-2-thienyl)quinazoline, 4-(2-hydroxyethylamino)-2-(5-nitro-2-thienyl)quinazoline 4-(2,3-dihydroxypropylamino)-2-(5-nitro-2-thienyl)quinazoline, and 1,2-dihydro-2-(5-nitro-2-thienyl)quinazolin-4(3H)-one. Another nitrofuran, 4,6-dimethyl-2-(5-nitro-2-furyl)-pyrimidine, provided the following types of neoplasms in 30 female rats at risk: squamous cell carcinomas of the forestomach (30), sarcomas of the intestine (21), adenocarcinomas of the kidney (2).
D000230:Adenocarcinoma / Q000139:chemically induced; D000232:Adenofibroma / Q000139:chemically induced; D000818:Animals; D002273:Carcinogens; D002294:Carcinoma, Squamous Cell / Q000139:chemically induced; D055598:Chemical Phenomena; D002621:Chemistry; D005260:Female; D006390:Hemangioendothelioma / Q000139:chemically induced; D007414:Intestinal Neoplasms / Q000139:chemically induced; D007890:Leiomyosarcoma / Q000139:chemically induced; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced; D009374:Neoplasms, Experimental / Q000139:chemically induced*; D009581:Nitrofurans / Q000633:toxicity*; D051381:Rats; D012513:Sarcoma, Experimental / Q000139:chemically induced; D013876:Thiophenes / Q000633:toxicity*
D002273:Carcinogens; D009581:Nitrofurans; D013876:Thiophenes