Anticancer activity and flavonoid content of various Citrus juices

It is commonly accepted that cancer formation can be prevented by the consumption of certain foods; thus flavonoids in Citrus fruits and juices are among the most prominent anticancer agents. From a viewpoint of health-promotion by dietary habits, cancer preventative activity in the Citrus juices is more important than that found in their inedible parts. However, few studies have focused on the biological activities in Citrus juices, possibly because the measurable activities in juices tend to be hindered by the more abundant substances, such as sugars. In order to eliminate the masking, we prepared the readily extractable fractions of Citrus juices by adsorbing on porous polymer resin, and successive elution from the resin with ethanol and acetone. Among 34 Citrus juices examined, King (C. nobilis) exhibited potent differentiation-inducing activity toward HL-60 leukemia cells, and the active principles were identified as four polymethoxyflavones. (C) 2004 American Chemical Society.