Carcinogenicity of naturally occurring 1-hydroxyanthraquinone in rats: induction of large bowel, liver and stomach neoplasms.

The carcinogenic potential of 1-hydroxyanthraquinone (HA), a naturally occurring compound, was examined. A total of 60 male ACI/N rats, 1.5 months old at the commencement were divided into two groups. Group 1 (30 rats) were fed the diet containing HA at a concentration of 1% throughout the experiment (480 days). Group 2 (30 rats) served as the control given a basal diet alone. Twenty-five of 29 effective animals in group 1 developed adenomas or adenocarcinomas in the cecum or upper portion of the colon, the mean number of large bowel tumors/tumor bearing rat being 2.3. In addition to these intestinal tumors, liver neoplasms (neoplastic nodules and hepatocellular carcinomas) were observed in 12 rats and benign stomach tumors were obtained in five animals; no rats of group 2 demonstrating development of any of these tumor types. The incidences of the large bowel, liver and stomach neoplasms in group 1 were all significant as compared with group 2 (P less than 2 x 10(-13), P less than 5 x 10(-5) and P less than 3 x 10(-2) respectively) clearly indicating that HA is carcinogenic in rats.