The Secret of Soy,What is Soy Isoflavones?Function of Natural Genistein?Soy Bean Extract.

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Actions and Pharmacology.

Soy Bean Extract INCI Name Glycine Soja Extract Soy Isoflavones Genistein Daidzein CAS 84776-91-0 Genistein CAS 446-72-0 Daidzein CAS486-66-8 photo picture image How do isoflavones work?

 In the eighties, scientists discovered the alpha- and beta-receptors for estrogens. Estrogens, like all hormones, act by using receptors located on the cell, which provokes some reaction. The alpha-receptors are linked with a risk of estrogen related cancers. On the other hand, the beta-receptors initiate only favourable effects. The repartition of these two types of receptors in the cells and organs is different. Different tissues appear to have different ratios of each receptor type. This discovery allowed us to understand why isoflavones can act differently than estrogens even though the structure of isoflavones is similar to estrogens.

 The isoflavones mechanism:Mechanism of Action:

 How can we explain that isoflavones have an estrogenic effect and an anti-estrogenic effect? When the natural levels of estrogens are low, isoflavones can help the estrogens by activating the beta-receptors.

 When the natural levels of estrogen are high, for example during Adolescence , the isoflavones bind with the alpha-receptors and prevent the natural estrogens from binding with these receptors.

 Soy isoflavones have weak estrogenic activity. The order of activity in in vivo assays is glycitein greater than genistein greater than daidzein. They bind to estrogen receptors-alpha and beta. They appear to bind better to estrogen receptor-beta than to estrogen receptor-alpha.

 The most studied of the soy isoflavones is genistein. Genistein has been found to have a number of antioxidant activities. It is a scavenger of reactive oxygen species and inhibits lipid peroxidation. It also inhibits superoxide anion generation by the enzyme xanthine oxidase. In addition, genistein, in animal experiments, has been found to increase the activities of the antioxidant enzymes superoxide dismutase, glutathionine peroxidase, catalase and glutathione reductase. Daidzein and glycitein also appear to have reactive oxygen scavenging activity. However, these isoflavones have not been studied as much as genistein has.

 Regarding possible anticarcinogenic activity, again genistein has been the most studied of the soy isoflavones. Several mechanisms have been proposed for genistein's possible anticarcinogenic activity. These include upregulation of apoptosis, inhibition of angiogenesis, inhibition of DNA topoisomerase II and inhibition of protein tyrosine kinases. Genistein's weak estrogenic activity may be involved in its putative activity against prostate cancer. Other possible anti-prostate cancer mechanisms include inhibition of NF (nuclear factor)-kappa B in prostate cancer cells, downregulation of TGF (transforming growth factor)-beta and inhibition of EGF (epidermal growth factor)- stimulated growth. Genistein's anti-estrogenic action may be another possible mechanism to explain its putative activity against breast cancer. Additional possible anti-breast cancer mechanisms include inhibition of aromatase activity and stimulation of sex hormone binding globulin, both of which might lower endogenous estrogen levels.

 The possible anti-atherogenic activity of soy isoflavones may be accounted for, in part, by their possible antioxidant activity, particularly with regard to inhibition of lipid peroxidation and oxidation of LDL. Soy isoflavones may have some cholesterol-lowering activity, but the mechanism of this possible effect is unclear.

 Soy isoflavone's weak estrogenic effect may help protect against osteoporosis by preventing bone resorption and promoting bone density. However, the mechanism of this possible effect is entirely speculative at this time.
 Soy Bean Extract INCI Name Glycine Soja Extract Soy Isoflavones Genistein Daidzein CAS 84776-91-0 Genistein CAS 446-72-0 Daidzein CAS486-66-8 photo picture image

 How do isoflavones influence health?:

 Isoflavones activate the beta-receptor and reinforce the favourable estrogenic properties. On the other hand, isoflavones protect the estrogen alpha-receptors. Consequently the proneness to estrogen-related cancers is lower.

 The beta-receptors, which exercise favourable effects for health, can be found mainly in the blood cells, the lungs, the prostate, the bladder, bones and thymus. Isoflavones stimulate their function even after the level of estrogens has decreased.

 The alpha-receptor can be mainly found in the breast tissue, the uterus, the ovaries, the testicles and the liver. In those places, isoflavones protect the receptor against estrogens and help reduce the proneness to tumors.

 Regulation of the hormonal balance during menopause:

 Isoflavones regulate the estrogen levels in the body. Isoflavones play a role when the estrogen level is low. The typical symptoms of the menopause, such as hot flushes and night sweat become less severe.

 When taking daily 40-50mg of isoflavones, the symptoms of menopause will decrease after 2 to 3. This treatment will also reduce the risk of hormones related tumors, osteoporosis and arterio-sclerosis. In the long term the health benefits are really high.

 Other isoflavones actions:

 Soy isoflavones have estrogenic activity. Soy isoflavones may have antioxidant activity. They may also have anticarcinogenic, anti-atherogenic, hypolipidemic and anti-osteoporotic activities. Most interest in isoflavones has been generated by their potential hormonal effects. But isoflavones have other physiological effects. There are indications that isoflavones can stop the growth of cancer cells through inhibition of DNA replication and reduction in the activity of various enzymes. Isoflavones also have antioxidant effects and inhibit the actions of various growth factors.
 Soy Bean Extract INCI Name Glycine Soja Extract Soy Isoflavones Genistein Daidzein CAS 84776-91-0 Genistein CAS 446-72-0 Daidzein CAS486-66-8 photo picture image

 Metabolism of isoflavones:

 Formation of aglycones:

 Isoflavones occur in foods in the form of glucosides which means that the isoflavones are bound to sugar (conjugated isoflavones). These glycosides are very water soluble. These conjugated isoflavones have to undergo further changes. When ingested, these conjugated isoflavones undergo hydrolysis by ?-glucosidases in the intestine, releasing the principal bioactive aglycones (daidzein, genistein and glycitein). These aglycones may be absorbed and further metabolized to many specific metabolites such as equol.

 Influence of diet on isoflavones metabolism:

 Further metabolism of aglycones seems to be strongly influenced by the diet. A high carbohydrate environment, which causes increased intestinal fermentation, results in more phytoestrogens being transformed in equol. This may be relevant because the potency of equol is higher than that of its plant precursor, daidzein. Also, the intestinal microflora has an effect on the metabolism of isoflavones. When intestinal flora is low (antibiotics, germfree animals, newborn babies) metabolism falls down too. When the dietary intake of fat is high, intestinal microflora has difficulty in synthesizing equol from isoflavones.

 Like endogenous estrogens (estradiol), isoflavones are metabolized in the intestines and liver. Absorption happens along the entire length of the intestine and they are secreted in bile and urine. Excretion of isoflavones metabolites can vary strongly between individuals. This may be influenced by the fact that each person has his own specific intestinal microflora population.

 Once absorbed equol shows less affinity to be bound to serum proteins and therefore has a greater availability than estradiol. When soy is consumed on a regular basis (50 mg isoflavones/day), plasma isoflavone levels far exceed normal estradiol concentrations. This observation led to the hypothesis that isoflavone would be biologically active, conferring health benefits that could explain the relatively low incidence of hormone-dependent diseases in countries in which soy is a dietary staple.

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Reference:

citations1.The Secret of Soy,What is Soy Isoflavones?Function of Natural Genistein?Soy Bean Extract.

last edit date:6th,May.2009.