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发表于 2009-5-7 23:51:10
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来自： 美国
是从大豆和豆腐以及一些植物中提炼出来的物质，没有查到FDA批准书，好像是保健食品
Genistein
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Genistein
IUPAC name
[show]
5,7-Dihydroxy-3-(4-hydroxyphenyl)chromen-4-one
Other names 4',5,7-Trihydroxyisoflavone
Identifiers
CAS number [446-72-0]
PubChem 5280961
SMILES
[show]
C1=CC(=CC=C1C2=COC3=CC(=CC(=C3C2=O)O)O)O
Properties
Molecular formula C15H10O5
Molar mass 270.24 g mol−1
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)
Infobox references
Genistein is one of several known isoflavones. Isoflavones, such as genistein and daidzein, are found in a number of plants, with soybeans and soy products like tofu and textured vegetable protein being the primary food source. Soy isoflavones are a group of compounds found in and isolated from the soybean. Besides functioning as antioxidants, many isoflavones have been shown to interact with animal and human estrogen receptors, causing effects in the body similar to those caused by the hormone estrogen. Soy isoflavones also produce non-hormonal effects.
Contents
[hide]
* 1 Biological effects
o 1.1 Antioxidant
o 1.2 Atherosclerosis
o 1.3 Cancer links
o 1.4 Effects in males
* 2 Molecular function
* 3 Sources
* 4 References
[edit] Biological effects
[edit] Antioxidant
Some isoflavones act as antioxidants to counteract damaging effects of free radicals in tissues. Genistein has a converse effect in this area compared to other isoflavones; It stimulates a step in nitrate synthesis, which is oxidation.[1]
[edit] Atherosclerosis
Genistein protects against pro-inflammatory factor-induced vascular endothelial barrier dysfunction and inhibits leukocyte-endothelium interaction, thereby modulating vascular inflammation, a major event in the pathogenesis of atherosclerosis.[2]
[edit] Cancer links
Some isoflavones have been found to have antiangiogenic effects (blocking formation of new blood vessels), and may block the uncontrolled cell growth associated with cancer, most likely by inhibiting the activity of substances in the body that regulate cell division and cell survival (growth factors). However, Genistein has the effect of promoting breast cancer in one study.[3]
Studies show that gastrointestinal cancer occurs less frequently among North Americans who do not learn to eat meat. North Americans who go to other continents without learning to eat vegetables show more digestive tract cancer than neighbours.[4]
Timing of phytoestrogen use is important.[5]
Genistein makes some cells more sensitive to radio-therapy.[5]
Though research is still ongoing, some recent studies have indicated that soy's phytoestrogens could be contributive factors in some forms of breast cancer, penile birth defects, and infantile leukemia.[6]
Some studies have raised the concern that genistein might increase the risk of leukemia, because it inhibits the enzyme topoisomerase which results in double strand DNA breaks, which are, in turn, mutagenic. Some cancer patients whose chemotherapy drugs inhibited topoisomerase later developed leukemia. An animal study suggested that GEN may not be safe for postmenopausal women with estrogen-dependent breast cancer.[7]
Regardless, soy's phytoestrogens, or isoflavones, have been definitely shown to depress thyroid function and to cause infertility in every animal species studied so far.[8] [9]
Genistein's chief method of activity is as a tyrosine kinase inhibitor. Tyrosine kinases are less widespread than their ser/thr counterparts but implicated in almost all cell growth and proliferation signal cascades. Genistein has been used to selectively target pre B-cells via conjugation with an antibody. This highly successful study in mice has promising benefits for future chemotherapy
[edit] Effects in males
Isoflavones can act like estrogen, stimulating development and maintenance of female characteristics or they can block cells from using cousins of estrogen. In vitro studies have proven genistein to induce apoptosis of testicular cells at certain levels, thus raising concerns about effects it could have on male fertility.[10]
[edit] Molecular function
Genistein influences several targets in living cells. One important function is the inhibition of several tyrosine kinases. Genistein also inhibits the mammalian hexose transporter GLUT1 and contraction of several types of smooth muscles. Genistein can bind to the CFTR channel, potentiating its opening at low concentration and inhibiting it a higher doses.
[edit] Sources
Concentrations of genistein in Pueraria mirifica (White Kawo Krua) are so close to zero that experimental estimates of error equalled concentration measured. [11] |
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IP卡
狗仔卡
提升卡
置顶卡
沉默卡
喧嚣卡
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抢沙发
千斤顶
显身卡