Citrus provide protection against certain types of cancer due to the presence of specific bioactive compounds such as flavonoids, carotenoids and tri‐terpenoids (mainly limonoids). Limonoids are known to inhibit number of human cancer cells through altering various biochemical pathways. Limonoids have shown induction of Phase II enzymes (both GST and QR) in mice suggesting their potential role in cancer prevention detoxification. Research form our laboratory has shown limonoids can induce apoptosis in colon, breast carcinoma and neuroblastom cells. Certain limonoids and flavonoids have shown induction of caspase mediated apoptosis and our recent in vivo study has shown inhibition of inflammatory proteins expression in Azoxymethane induced rats. Limonin and its glucoside have shown induction of intrinsic apoptosis, though involvement of Ca++ in SW‐480 cells. These limonoids were non‐toxic against 112CoN and NIH3T3 cells. Nomilin, one of the abundant limonoids found in citrus, has shown to arrest cell cycle of colon cancer cells when treated at 200µM. On the other hand, flavonoids of citrus demonstrated structure‐related inhibition of colon cancer cells. Among the eight major flavonoids of citrus (which includes flavone, flavonols and flavanones), molecules with double bond at carbon 2nd and 3rd position have shown potential inhibition. Furthermore, the flavonoids, with higher number of hydroxyl groups, have shown significant induction of apoptosis. Apigenin and Quercetagetin have shown significant induction of apoptosis in colon cancer cells. The results of these findings will be discussed in detail. These results are based on the work supported by the USDA‐CSREES # 2009‐34402‐19831 “Designing Foods for Health” through the Vegetable and Fruit Improvement Center.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):B72.