ABSTRACT
Daidzein, one of the major isoflavone aglycones in soybean, is usually present in the form of its
β
-glucoside, daizin. While isoflavones are bitter and astringent, they all exhibit antihemolytic, antioxidative, antifungal, estrogenic, and antitumoral properties (Naim et al.,
1976; Farmakaladis et al.,
1985; Miyazawa et al.,
1999). It is the antioxidant properties of isoflavones that are generally attributed for their anticancer properties (Ruiz-Larrea et al.,
1997; Stoll, 1997). The free-radical-quenching properties of daidzen prevented the formation of oxidized DNA, 8-hydroxy-2
′
-deoxy-guanosine, in cells and DNA exposed to oxidants or in men
consuming 1 liter of soy milk daily over a fourweek period (Giles and Zwei, 1997; Mitchell and Collins, 1999). Djuric et al. (2001) conducted a pilot study in which a combination of daidzein and genistein, in the form of a tablet, reduced endogenous oxidative DNA damage, as measured as 5-hydroxymethyl-2
′
-deoxyuridine (5OhmdU), in the blood cells of men and women kept on a twice-daily regimen of 50 mg isoflavone tablets for three weeks. After one week of supplementation, there was a 61 percent decrease in 5OhmdU in the blood cells of women, while it took three weeks before there was a corresponding decrease of 47 percent in men. This reduction in oxidative damage was considered a possible mechanism for its anticancer properties. Guo and coworkers (2004) showed daidzein had a biphasic effect on the
cell growth of a human colon-cancer cell line LoVo. At low concentrations (
<
µ
M) daidzein stimulated growth, while at high concentrations (
>
µ
M) cell growth was inhibited in a dosedependent manner. Inhibition of cell growth was characterized by cell-cycle arrest at G0/G1, DNA fragmentation, and enhanced caspase-3 activity.
