| Abstract
| - Research in this laboratory has shown that some citrus limonoids can inhibit the development of7,12-dimethylbenz[a]anthracene-induced oral tumors. The data from these studies have suggestedthat certain rings in the limonoid nucleus may be critical to antineoplastic activity. Using the hamstercheek pouch model, three new limonoids (ichangensin, deoxylimonin, and obacunone) have nowbeen tested for cancer chemopreventive activity. In the first experiment, it was found that the treatmentswith ichangensin had no effect on tumor number or burden. In the second experiment, obacunonereduced tumor number and burden by 25 and 40%, respectively, whereas deoxylimonin reducedtumor number and burden by 30 and 50%, respectively. The results with deoxylimonin were significant,p< 0.05. Overall, the data indicated that changes in the A ring of the limonoid nucleus can lead toa loss of anticancer activity, whereas changes in the D ring can be tolerated without any apparentloss of biological activity. Keywords: Limonoids; oral carcinogenesis; citrus; anticancer activity
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