Lack of chemopreventive effects of α-eleostearic acid on 7,12-dimethylbenz[a]anthracene (DMBA) and 1,2-dimethylhydrazine (DMH)-induced mammary and colon carcinogenesis in female Sprague–Dawley rats

α-Eleostearic acid is one of the conjugated linolenic acids from tung oil, which is obtained from the seeds of Aleurites fordii. The effects of dietary α-eleostearic acid (18:3, n-5) on the post-initiation period of 7,12-dimethylbenz[a]anthracene (DMBA) and 1,2-dimethylhydrazine (DMH)-induced mammary and colon carcinogenesis were examined using female Sprague–Dawley (SD) rats. For initiation, rats were given subcutaneous injections of 40 mg/kg body weight (5 times) and 20 mg/kg body weight (3 times) of DMH during the age of 6–8 weeks and a single intragastric administration of 50 mg/kg body weight of DMBA at 9 weeks. Then, the animals were treated with 0%, 0.01%, 0.1% or 1.0% α-eleostearic acid for 34 weeks. Control rats received the basal diet alone or 1.0% α-eleostearic acid without prior initiation treatment. All surviving animals were killed at week 37 of the experiment. There were no statistically significant alterations in any of the parameters for either mammary or colon tumors. These results thus indicate that α-eleostearic acid does not exert clear modification effects on DMBA and DMH-induced mammary and colon carcinogenesis, at least under the present experimental conditions.