PHYTOESTROGENS: Genistein shows antiproliferative effect against estrogen dependent breast carcinoma

[Guest guest]

PHYTOESTROGENS

Sharol Tilgner N.D.

 

The term phytoestrogen is used loosely in the herbal community. There is

no current agreed upon definition for this term.

 

Basically the term is used for any plant that has one or more

constituents with similar chemical structure to estrogen or is changed

into a similar compound in vivo or clinically produces effects that the

clinician would expect from giving exogenous estrogens.

 

Plants may have compounds that are structurally similar to human

endogenous estrogens that mimic estrogenic activity or effect estrogen

metabolism.

 

Some plants may show an estrogenic effect in laboratory studies, animal

studies or in clinical settings but the specific constituent or mode of

action has not been identified.

 

It is thought that the weaker phytoestrogens can compete for estrogen

receptors with the more potent endogenous estrogens thereby decreasing

the overall estrogenic activity when it is deemed to be too high.

 

When endogenous estrogens are low and phytoestrogens are used in large

quantities, phytoestrogens have been shown to exert an estrogenic effect

in animals. The phytoestrogens can take up receptor sites that are empty

due to low estrogen levels.

 

Most of the identified phytoestrogen constituents consist of sterols,

coumestans and isoflavones.

 

There are more than 300 plants, which have been identified as possessing

estrogenic or uterotropic activity.

 

Phytoestrogens compete with estradiol for estrogen binding sites in the

reproductive tracts of animals in vivo and in human breast cancer cells

in vitro. 220-2222, 223

 

Phytoestrogens will produce similar results to estrogens such as growth

and increased weight of the uterus. Research measuring weight increase

of uteri in mice showed sterols to have the most activity, followed by

coumestans and then isoflavones. 224, 291

 

Coumestans have a high affinity for the human estrogen receptor. 283

They are estimated to be 200 times less potent than estrone and 3000

times less potent than diethylstilbestrol, and 30-100 times more potent

than isoflavones.

 

Animal studies have shown coumestans can reduce follicle-stimulating

hormone and lutenizing hormone levels.

 

Coumestans produce uterine growth in rats at natural dietary levels and

competitively inhibit binding to the estrogen receptors.

 

Not all isoflavones have estrogenic effects, but many of them do. Some

of them need to be converted by gut bacteria to other compounds to be

effective.

 

If a person is using antibiotics or ingesting other substances that

destroy gut flora, there would be decreased isoflavone conversion in the

gut, and the herb would not work as expected.

 

The isoflavone, Genistein,

has shown *antiproliferative effects* against " estrogen-dependent " and

independent human " breast carcinoma " cell lines.

 

 

Phytoestrogens can act as anti-estrogens to compete with estradiol for

cytoplasmic receptors in estrogen-sensitive tissues.

 

Soybeans, which also contain estrogenic isoflavones, have been

implicated as being responsible for the low incidence of breast and

other female reproductive cancers in Japanese woman who consume large

amounts of soybean products.

 

Studies show a correlation between high levels of urninary lignans and

isoflavonoid phytoestrogens, specifically genistein,

 

and a low incidence

of hormone-dependent cancers such as breast and prostate cancer.

 

In vitro studies show genistein and daidzein inhibit growth of both

estrogen receptor-positive and estrogen receptor-negative human breast

cancer cell lines (IC50=24-44um).432

 

Dietary phytoestrogenes dilute

" xenoestrogen-type " *carcinogens* by " binding " at the receptor sites and

acting as antiestrogens. 433

 

The phytoestrogens genistein and daidzein tend towards " normalizing "

 

estrogen and progesterone levels.

 

Lignans are phenolic compounds with weak estrogenic activity.

 

They have been linked to a " lowered incidence " of breast cancer.

 

The highest concentrations of estrogenically-active lignans are in the

defatted portion of flax seeds.

 

They are converted by gut bacteria to mammalian lignans, the primary

ones being enterolactone and enterodiol. They are structurally similar to

estrogen and bind with low affinity to estrogen receptors.

 

They also increase sex hormone binding protein.

 

The most " potent phytoestrogens " are the *phytosterols*.

 

Common foods, which

contain phytosterols, are chestnuts, sesame and pumpkin seeds.

 

Phytosterols are most common in organic whole grains, nuts, seeds and

legumes.

 

The sterol, beta-sitosterol has phytoestrogen activity as well

as anti-inflammatory activity and antipyretic activity.

 

It can be found in Achillea millefolium, Anemone pratensis, Angelica

sinensis, Calendula officinalis, Glycyrrhiza glabra, Hypericum

perforatum, Larrea spp., Panax spp., Piscidia erythrina, Plantago

psyllium, Serenoa repens, Symphytum spp., Taraxacum officinale,

Trifolium pratense, Turnera spp., Tussilago farfara, Valeriana

officinalis, Viburnum prunifolium. 289, 290 A fat soluble extract of

Humulus lupus was found to contain small amounts of estradiol. 225

Water-soluble glycoproteins from Hops strobiles are antigonadotropic and

suppress progesterone production by luteal cells in rats. 226,227

 

Dioscorea species contain the steroidal sapogenin called diosgenin.

 

Diosgenin is manipulated chemically in laboratories to create estrone,

testosterone, and progesterone as well as adrenocortical hormones.

 

In

current research on animals, it appears that diosgenin usually turns

into smilagenin due to action on it by gut flora.

 

Both animals and humans poorly absorb diosgenin itself. 231 When

diosgenin was given orally to female rats they had an increase in

uterine weight, vaginal opening and vaginal cornification. 232 When

injected into ovariectomized mice there was a growth of mammary

epithelium. 233 Chamaelirium and Aletris both contain diosgenin and have

produced estrogenic activity in rats. 234 Cimicifuga (Black cohosh)

contains the isoflavone formononetin and two other unidentified

endocrine-active compounds, which appear to have estrogenic activity via

competition for estrogen receptors. 235

 

Black cohosh has been shown to suppress luteinizing hormone secretion in

menopausal woman and competes in vitro with 17-beta-estradiol for

estrogen receptor binding sites. 37

 

Black Cohosh has an inhibitory activity in vitro and in vivo on bone

resorption in ovariectomized rats as well as rats on low calcium diets.

265, 266 The active constituents in black cohosh are thought to be 1.)

Triterpene glycosides, principally actein, 27-deoxyactein,

cimicifugoside and cimigenol 3-O-alpha-L-arabinopyranoside and related

aglycones, 2.) Isoflavones including formonoetin,

 

3.) Aromatic acids including isoferulic acid, ferulic acid, and

salicylic acid. 281

 

*Legumes* are a good source of 'edible phytoestrogens'.

Soybeans are one of the most highly researched source of phytoestrogens

..

They are currently thought to be one of the best sources of edible

phytoestrogens. Additionally, soybean sprouts have the highest

concentration of isoflavones.

 

Health care practitioners have been

concerned about giving plants with phytoestrogens to patients that have

estrogen sensitive breast cancer.

 

Research has shown that women

'consuming' " high amounts " of *phytoestrogens* in their diet have had a

decreased incidence of breast cancer rates. 292, 293, 294

 

 

Sharol Tilgner (Author of Herbal Medicine: From the Heart of the Earth:)

 

 

Wise Acres

stil-

www.planetherbs.com

_________________

 

JoAnn Guest

mrsjoguest

DietaryTipsForHBP

www.geocities.com/mrsjoguest/Genes

 

 

 

 

AIM Barleygreen

" Wisdom of the Past, Food of the Future "

 

http://www.geocities.com/mrsjoguest/Diets.html