Daidzein structure

Figure 3 Structures of daidzein, liquiritigenin, naringenin, couniestrol, genistein, and isoiiquiritigenin, the substances identified by high-performance liquid chromatography. Biosynthetic relationships of compounds are indicated. (From Ref. 13.)...

Fig. 2.86. Chemical structures of the iosflavones daidzein, genistein, O-desmethylangolensin, equol, and the lignans enterolactone and enterodiol. Reprinted with permission from Z. Kuklenyik el al. [209].

FIGURE 7.2 Chemical structures of the main soy (genistein and daidzein) and red clover (biochanin A and formononetin) isoflavonoids (aglycones and glucosides). 

FIGURE 8.6 Structure of the phytoalexin isoflavonoid pterocarpans, maackianin, and pisatin from garden pea, and the isoflavones daidzein and genistein from soybean. 

As previously mentioned, certain flavonoids can penetrate into the hydrophobic core of membranes, a feature that mainly relies on their hydrophobic character, which is dictated by flavanoid chemical structure and spatial conformation. When flavonoid hydrophobicity was assessed from the partition coefficient between ra-octanol and an aqueous solution, the following order of hydrophobicity was observed flavone, genistein > eriodictyol, myricetin, quercetin, kaempferol, hesperetin, daidzein > > galangin, morin, flavanone, naringenin, taxifolin (Table 4.1). 

The isoflavones found in soy bean extracts, such as genistein and daidzein, that are phytoestrogens, are also able to enhance HA deposition.281,282 Their estrogen-like structures may account for their ability to enhance HA deposition. 

Figure 4.1 Chemical structures of the principal classes of polyphenols. The examples shown are of polyphenols with hydroxyl groups in the 7- and 4"-positions. Anthocyanins may also be found in oligomeric forms. The coumestane is coumestrol, The isoflavone (daidzein) differs from the flavonoid h the substitution of the phenolic group. For the flavonoid it is in the 2-position, whereas it is in the 3-position in the isoflavone.

Structural similarity of the isoflavones to estrogen has been responsible for claims that they are natural alternatives to hormone replacement therapy (HRT). Soy isoflavones are not usually present in humans, unless caused by acute or chronic administration of soy products in the diet. If not in the diet, supplementation is required. One synthetic isoflavone, ipriflavone, has been shown to increase bone mass in postmenopausal women. The soy isoflavone daidzein makes up 10%o of the metabolites of ipriflavone, and it appears to be one of the metabolites that inhibit osteoclast activity in vitro. A number of studies have been reported on the effects of soy protein and genistein on bone density in rats, and it appears that it is the isoflavones that are responsible for the beneficial effects. Positive data from studies with cultured bone cells support a... 

Phytoestrogens. Several natural plant substances that have general structural features similar to those of DBS and estradiol also have estrogenic effects and have been termed phyioestrogetLs. These include genistein. from soybeans and a species of clover, daidzein. from. soybeans and coume-strol, found in certain legumes. Genistein and daidzein are... 

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