Daidzein

Infant s food Matrix analysed Age (months) Isoflavone level (ng/ml) Genistein Daidzein Equal... 

Inhibition of steroid sulphatase and sulphotransferase Steroid sulphotransferase catalyses the addition of sulphate to steroidal compounds whilst steroid sulphatase catalyses the reverse reaction. In vitro studies have demonstrated that a metabolite of genistein, 4-ethylphenol, can inhibit sulphotransferase (Harris et al, 2000). Sulphoconjugates of daidzein have also been found to potently inhibit these enzymes in vitro (Wong and... 

J p (2000) Daidzein is more efficient than genistein in preventing ovariectomy-induced bone loss in rats. J Nutr. 130 1675-81. 

RUPP H, ZOLLER o, ziMMERELi B (2000) Bestimmung der isoflavone daidzein imd genistein in sohaltigen produkten. Mitt Lebsesm Hyg. 91 199-223. 

WONG c K, KEUNG w M (1997) Daidzein sulfoconjugates are potent inhibitors of sterol sulfatase (EC 3.1.6.2). Biochem Biophys Res Commun. 233 579-83. 

ZHANG R, LI Y, WANG w (1997) Enhancement of immune function in mice fed high doses of soy daidzein. Nutr Cancer. 29 24-8. 

The major isoflavones in soy are genistein, daidzein and glycitein (reviewed by Setchell, 1998 Setchell and Cassidy, 1999). Isoflavone content varies among soybean varieties, growing conditions and soil (Wang and Murphy,... 

Picherit et al., 2000 1 yr old OVX rats oral administration, 90 d genistein or daidzein at 10 mg/kg body weight Overall daidzein > genistein in this study. Total femoral BMD losses and vertebral trabecular bone were protected by estradiol and daidzein, but genistein was not efficient. Bone strength (femoral failure stress) protected by estradiol, daidzein and genistein... 

Rassi et al., 2002 Porcine bone marrow cells measure osteoclast formation (TRAP staining) and activity (pit assay) Daidzein, at the same concentration as estradiol, inhibits osteoclast formation and activity via caspase-3. 

Tobe et al., 1997 Pit assay with mouse bone marrow cells and dentine slices Daidzein (IQ-Yio-iom) stimulated pit formation while genistein had no effect at this concentration. 

Gao and Yamaguchi, 1999a Yamaguchi and Ma, 2001 Femoral-diaphyseal tissues from elderly female rats cultured for 24 h Daidzein or genistein (lO M, lO M) induced calcium content and alkaline phosphatase (ALP) activity indicating stimulation of bone formation. 

GAO Y H and YAMAGUCHI M (1999c) Anabolic effect of daidzein on cortical bone in tissue culture Comparison with genistein effect. Mol Cell Biochem 194, 93-8. 

RASSi c M, LIEBERHERR M, CHAUMAZ G, POINTILLART A and COURNOT G (2002) Down-regulation of osteoclast diferrentiation by daidzein via caspase 3. JBone Min Res 17, 630-38. 

SUGIMOTO E and yamaguchi m (2000b) Stimulatory effect of daidzein in osteoblastic MC3T3-E1 cells. Biochem Pharmacol 59, 471-5. 

TOBE H, KOMIYAMA o, KOMIYAMA Y and MARUYAMA H B (1997) Daidzein stimulation of bone resorption in pit formation assay. Biosci Biotechnol Biochem 61, 370-71. 

YAMAGUCHI M and suGiMOTO E (2000) Stimulatory effect of genistein and daidzein on protein synthesis in osteoblastic MC3T3-E1 cells Activation of aminoacyl-tRNA synthetase. Mol Cell Biochem 214, 97-102. 

Recently, some of the specific faecal bacteria involved in the metabolism of dietary isoflavonoids were isolated (Hur et al., 2000). They have been shown to selectively convert genistin and daidzin to their respective aglycones. One of the isolated bacteria, under anoxic conditions, was further shown to metabolise genistein and daidzein to their respective dihydroxy-genistein and dihydroxy-daidzein. In the case of lignans, enterodiol and enterolactone were shown to be excreted in vivo only in rats harbouring a gut microflora (Rowland et al, 1999). 

In addition to the effects on blood lipids, it has been suggested that soy consumption has a beneficial action on arterial function and improves antioxidant status (Lichtenstein, 1998 and refs therein). Genistein and daidzein were shown to have antioxidant properties in vitro (Kerry and Abbey, 1998), to enhance endothelium-dependent vasodilation and to reduce the development of atherosclerosis in monkeys (Honore et al, 1997 Wagner et al, 1997). 

Isoflavones have been implicated in goiter induction. Soybean extracts inhibit reactions catalyzed by thyroid peroxidase (TPO), essential to the synthesis of thyroid hormones (Divi et al., 1997). Genistein and daidzein (at about 1-10 p,M of IC50) may act as alternative substrates for tyrosine iodination (Divi et al., 1997). Furthermore, genistein and daidzein have also been shown to cause the irreversible inactivation of TPO in the presence of hydrogen peroxide. Genistein also inhibits thyroxine synthesis in the presence of iodinated... 

An inverse correlation between thyroid cancer risk and phytoestrogens was recently proposed as a result of a multi-ethnic population-based case control study conducted in the San Francisco Bay Area (Hom-Ross et al., 2002). In this study, dietary habits and phytoestrogen consumption were assessed by a food-frequency questionnaire and by a nutrient database. The outcome of the study was that soy-based foods and alfalfa sprouts were associated with a reduction of thyroid cancer risk, whereas a Western diet did not influence cancer risk. No difference was observed between American and Asian women or between pre- and postmenopausal women. Furthermore, among the few compounds examined, the isoflavones genistein and daidzein and the lignan secoisolariciresinol were the phytoestrogens most frequently associated with risk reduction (Horn-Ross et al., 2002). 

Data on safety have been obtained from in vitro as well as in vivo animal and human studies (see also Section 10.4). About 50 years ago, Australian farmers observed an infertility syndrome in sheep associated with the consumption of clover species (Bennets et al., 1946). The clover compounds shown to cause the infertility (genistein, daidzein, equol, biochanin A, formononetin) were members of the isoflavone family (Bradbury and White, 1951 Shutt and Braden, 1968), raising the question of whether soy might cause infertility in humans (see also Section 10.4.9). A variety of reports further supported adverse effects of isoflavones on animal reproductive systems (Santell et al., 1997 Flynn et al., 2000a,b). 

CHANG Y c and nair m g (1995) Metahohsm of daidzein and genistein by intestinal bacteria. JNat Prod. 58 (12) 1892-6. 

KING R A and BURSILL D B (1998) Plasma and urinary kinetics of the isoflavones daidzein and genistein after a single soy meal in humans. Am J Clin Nutr. 67 (5) 867-72. 

LIGGINS J, MULLIGAN A, RUNSWICK s and BINGHAM s A (2002) Daidzein and genistein content of cereals. Eur J Clin Nutr. 56 (10) 961-6. 

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