Citrus limonoids obacunone and limonin inhibit azoxymethane-induced colon carcinogenesis in rats
Article first published online: 16 DEC 2008
Copyright © 2000 International Union of Biochemistry and Molecular Biology, Inc.
Volume 13, Issue 1-4, pages 213–218, 2000
How to Cite
Tanaka, T., Kohno, H., Tsukio, Y., Honjo, S., Tanino, M., Miyake, M. and Wada, K. (2000), Citrus limonoids obacunone and limonin inhibit azoxymethane-induced colon carcinogenesis in rats. BioFactors, 13: 213–218. doi: 10.1002/biof.5520130133
- Issue published online: 16 DEC 2008
- Article first published online: 16 DEC 2008
- colon carcinogenesis;
Obacunone and limonin are bitter limonoids in citrus. Their modifying effects on the development of aberrant crypt foci (ACF), the activity of detoxification enzymes, glutathione S-transferase (GST) and quinone reductase (QR), and cell proliferation activity were investigated in male F344 rats treated with azoxymethane (AOM). Obacunone and limonin were administered in the diet, during the initiation (for 4 weeks) or postinitiation phase (for 4 weeks) of AOM-induced tumorigenesis. Feeding of obacunone and limonin (0.02% or 0.05%) caused significant reduction (55–65% by “initiation” feeding and 28–42% by “postinitiation” feeding) in the yield of ACF. The ability to reduce the proliferating cell nuclear antigen-labeling index in crypts and correlated well with the prevention of ACF. In a subsequent long-term experiment (38 weeks), in which rats were initiated with AOM and fed 0.05% obacunone or 0.05% limonin during the initiation or post-initiation phase, both compounds in diet caused significant reduction (65%–92% inhibition) in the incidence of colonic adenocarcinoma. Thus, citrus bitter limonoids obacunone and limonin possess chemopreventive effects on chemically induced rat colon carcinogenesis.