Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Equol”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed1995

Rapid HPLC analysis of dietary phytoestrogens from legumes and from human urine.

Due to growing evidence suggesting that phytoestrogens might protect against various cancers, particularly against breast and prostate cancer, it is important to measure the exposure of populations to these compounds by determining levels in food and in human tissue or body fluids to assess the possible cancer protective properties of these agents. Therefore, we developed a simple and fast procedure to extract and simultaneously hydrolyze phytoestrogens and their conjugates from food items, and present a fast and selective high-performance liquid chromatography (HPLC) method for precise determinations of the most common dietary phytoestrogens genistein, biochanin-A, daidzein, formononetin, and coumestrol using flavone as internal standard. For the first time HPLC was applied to measure these phytoestrogens and their most abundant metabolites equol and O-desmethyl-angolensin from human urine. The proposed methodology has been evaluated for losses due to thermal degradation during extraction and hydrolysis and due to sample handling during the entire work-up including solid phase extraction, and values are given for inter- and intra-assay variability. We present isoflavonoid levels of most common peas and beans used in "western" and "eastern" diets and compare isoflavonoid and coumestrol levels of raw, canned, and cooked foods which can be used in future epidemiological studies. We also determined human urinary levels with our methodology comparing values before and after soybean intake.

Chromans↗
PubMed1995

The variable metabolic response to dietary isoflavones in humans.

The aim of this study was to better understand the metabolic fate of dietary estrogenic isoflavones in humans. Twelve volunteers were challenged with soya flour and urinary levels of the isoflavones daidzein (Da), genistein (Gen), and glycitein (Gly), and the isoflavonoid metabolites equol (Eq) and O-desmethylangolensin (O-Dma) determined by GC and GC-MS. Prior to challenge, Da, Gen, and Gly were present in the urine of all participants at low levels and Eq and O-Dma were present in 9/12 and 10/12 participants, respectively. Urinary levels of all five diphenols were increased in each individual on the day following challenge, returning to approximately prechallenge levels on the second or third day post-challenge. Mean post-challenge peak levels of the five diphenols compared with pre-challenge levels were Da (4x), Gen (8x), Gly (5x), Eq (45x), and O-Dma (66x). However, there was considerable individual variation in this metabolic response with peak levels of Eq showing the highest variation (1527x). An inverse relationship between Eq and O-Dma excretion was also found post-challenge suggesting individual variability in the preferred metabolic pathways of dietary isoflavones.

4-Butyrolactone↗
PubMed2006

Phytoestrogen action in Leydig cells of Biłgoraj ganders (Anser anser).

The mechanism of phytoestrogen action in gonadal cells of ganders has not been elucidated. The aim of the study was to investigate in Biłgoraj ganders the possibility of phytoestrogen action via estrogen or androgen receptors or via protein tyrosine kinase pathways in Leydig cells. Genistein and daidzein (5 and 50 microM) as well as equol (50 microM) inhibited testosterone (T) secretion by incubated Leydig cells (1x10(5)/ml; 20 h; 37 degrees C). The effects of hydroxytamoxifen (estrogen receptor inhibitor) and cyproterone acetate (androgen receptor antagonist) on phytoestrogen inhibition of T release by Leydig cells were not observed. Lavendustin A (protein tyrosine kinases inhibitor) did not change T production. The influence of phytoestrogens seems not to be conducted via estrogen and androgen receptors or protein tyrosine kinases system in these cells, but further studies are required to completely examine the mechanism of phytoestrogens action in testes of ganders.

Animals↗
PubMed1998

Reliability of serum measurements of lignans and isoflavonoid phytoestrogens over a two-year period.

We examined the distribution and long-term reliability of serum measurements of the two main human lignans, enterolactone and enterodiol, and the isoflavonoid phytoestrogens daidzein, genistein, equol, and O-Desmethylangolensin in the New York University Women's Health Study, a prospective cohort study of sex hormones and breast cancer. Serum samples collected at three yearly visits in 30 premenopausal and 30 postmenopausal women who had not been diagnosed with cancer or cardiovascular disease were included in the study. Assays were carried out by ion-exchange chromatography and capillary gas chromatography-mass spectrometry. Levels of isoflavonoid phytoestrogens were low, often at or below the sensitivity level of the assay. The reliability coefficients for these compounds were also low (< or =0.30). The median levels of enterodiol and enterolactone were 1.52 nmol/liter and 20.2 nmol/liter, respectively, and were comparable with the levels observed in omnivorous Finnish women living in the Helsinki area. A substantial number of women, though, had fairly high levels: for instance, 15% of the assays showed levels of enterolactone greater than the mean level observed in vegetarian Finnish women, i.e., 89.1 nmol/liter (H. Adlercreutz et al., Cancer Detec. Prev., 18: 259-271, 1994). The reliability coefficient of a single measurement of enterolactone was moderately high (0.55), suggesting that serum measurements of this compound could be a useful tool in prospective epidemiological studies with access to repeated blood or serum specimens. For instance, the reliability coefficient of the average of three measurements of enterolactone would be 0.79, a level considered acceptable in light of the other sources of error that are present in epidemiological studies (W. Willett, Stat. Med., 8: 1031-1040, 1989).

4-Butyrolactone↗
PubMed1999

Urinary excretion of isoflavonoids and the risk of breast cancer.

Isoflavonoids are a group of biologically active phytochemicals that humans are exposed to mainly through soy food intake. Because of the similar chemical structure of these compounds and estradiol, it has been hypothesized that isoflavonoids may be related to the risk of breast cancer. Overnight urine samples from 60 incident breast cancer cases and their individually matched controls were assayed for urinary excretion rates of five major isoflavonoids (daidzein, genistein, glycitein, equol, and O-desmethylangolensin) and total phenols. These subjects were from a large population-based case-control study conducted in Shanghai, and urine samples from breast cancer cases were collected before any cancer therapy to minimize the potential influence of the disease and its sequelae on study results. Urinary excretion of total phenols and all individual isoflavonoids, particularly glycitein, was substantially lower in breast cancer cases than controls. For total isoflavonoids, the mean excretion was 13.95 nmol/mg creatinine (SD, 20.76 nmol/mg creatinine) for cases and 19.52 nmol/mg creatinine (SD, 25.36 nmol/mg creatinine) for controls (P for difference = 0.04). The case-control difference was more evident when median levels of these compounds were compared, with the median excretion of all major isoflavonoids being 50-65% lower in cases than in controls. Individuals in the highest tertile of daidzein, glycitein, and total isoflavonoids had about half the cancer risk of those in the lowest tertile. The adjusted odds ratio for breast cancer was 0.14 (95% confidence interval, 0.02-0.88) for women whose urinary excretion of both phenol and total isoflavonoids was in the upper 50% compared with those in the lower 50%. The results from this study support the hypothesis that a high intake of soy foods may reduce the risk of breast cancer.

Adult↗
PubMed1998

Inhibitory effects of soy and rye diets on the development of Dunning R3327 prostate adenocarcinoma in rats.

METHODS: Dunning R3327 PAP prostate tumors were transplanted in 125 rats, the rats were divided into five groups, and tumor development was examined for 24 weeks during treatment with diets containing 33% of soy flour (SD), rye bran (RB), heat-treated rye bran (HRB), or rye endosperm (RE). RESULTS: In the SD, RB, and HRB groups, significantly fewer palpable tumors and lower tumor volume were detected 14 and 16 weeks after transplantation when compared with the control, fiber-free dietary (FF) group. The body weight was lower 16 weeks after tumor transplantation in the RB and HRB groups when compared with the control group (P < 0.05). Rats in the RB and the HRB groups had a significant lower energy intake than the FF group during the first metabolic observation period, 3-6 weeks after tumor transplantation (P < 0.05), whereas the energy intake was the same in all groups during the second metabolic observation period, 13-16 weeks after tumor transplantation. However, when the tumor volume was adjusted for the body weight of the animals, there were still significant lower tumor volumes in the SD, RB, and HRB groups compared with the FF group (P < 0.05). A significant increase in daily urinary excretion of the isoflavonoids, daidzein, O-desmethylangolensin, equol, and Genistein, was observed in the rats fed SD, and of the ligands enterolactone and enterodiol in the rats fed RB and HRB during both metabolic periods. There were no differences in testosterone levels between the groups. CONCLUSIONS: The present study shows that SD inhibits implanted prostate cancer growth. Although RB and HRB had a protective effect, further studies are needed to exclude the possibility that a low energy intake played a role in this respect. The results suggest that phytoestrogens (isoflavonoids and ligands), may be responsible for the delayed prostate tumor growth.

Adenocarcinoma↗
PubMed1999

Antioxidant action and potential antidiabetic properties of an isoflavonoid-containing soyabean phytochemical extract (SPE).

The potential role of oestrogenic agents, antioxidants and intestinal glucose-uptake inhibitors in the treatment of diabetes is briefly reviewed. Reports in the literature suggest that oestrogen replacement therapy may favourably modulate glucose homeostasis. A soya phytochemical extract (SPE) containing the isoflavone phytoestrogens genistein and daidzein (mostly in their glycone forms as genistin and daidzin) was investigated as an antioxidant and modulator of intestinal glucose-transport. In the present study, SPE was found to protect against glucose-induced oxidation of human low density lipoproteins (LDL) in vitro. Equol (a gut bacterial metabolite of daidzein) was a more effective antioxidant than daidzein or genistein in this system and was of similar antioxidant potency to the dietary flavonols quercetin and kaempferol and to the endogenous antioxidant 17beta-oestradiol. SPE was found to be an inhibitor of glucose uptake into rabbit intestinal brush border membrane vesicles in vitro, though of weaker potency than the classical sodium dependent glucose transporter (SGLT) inhibitor, phlorizin. Thus SPE displays a range of properties which may be of benefit in diabetes, namely as an oestrogenic agent, an inhibitor of intestinal glucose-uptake and a preventive agent for glucose-induced lipid peroxidation.

Animals↗
PubMed2004

Novel physiological function of fructooligosaccharides.

Two key properties of short chain fructooligosaccharides (sc-FOS) which lead to physiological functions are indigestibility in the small intestine and fermentability in the colon. Sc-FOS is converted into short chain fatty acids (SCFAs) by intestinal bacteria in the colon and absorbed. Through the metabolic pathway, sc-FOS improves gastrointestinal (GI) condition such as relief from constipation, formation of preferable intestinal microflora and intestinal immunomodulation those are known as prebiotics' function. Besides improvement of GI condition, dietary sc-FOS influences on calcium and magnesium absorption in the colon. A major mineral absorption site is the small intestine, but the colon also works as a Ca and Mg absorption site with an aid of SCFAs made from sc-FOS. Furthermore dietary sc-FOS influences on bioavailability of soy-isoflavones. Plasma and urinal concentration of Genistein and Daidzein, aglycones of Daidzin and Genistin, are higher in the rat fed with sc-FOS than the control rat. An additive effect of dietary isoflavone and sc-FOS was observed on the bone mineral density in OVX mice and moreover sc-FOS increased ceacal beta-glycosidase activity and equol production. These results suggest that FOS increase the bioavailability of isoflavones.

Animals↗
PubMed2006

The effects of short-term oral phytoestrogen supplementation on the hypothalamic-pituitary-testicular axis in prostate cancer patients.

BACKGROUND: Here we evaluate the effects of oral phytoestrogen supplementation on hypothalamic-pituitary-testicular (HPT) axis in CaP patients. METHODS: We recruited 40 men about to undergo radical prostatectomy for CaP to receive either 240 mg of clover phytoestrogens or placebo daily for 2 weeks. Serum hormone levels were measured before and after treatment. In addition, recombinant cell bioassay was used to measure serum androgen bioactivity (ABA). RESULTS: Phytoestrogen treatment increased serum LH from mean of 3.4-5.2 IU, P = 0.03. Concomitantly, non-significant trend towards decline in serum T, cfT and ABA values was noted. However, mean serum LH/T ratio was upregulated from 0.20 to 0.48 IU/nM, P = 0.004, suggesting compensated hypogonadism. During the course of treatment, serum concentration of equol correlated strongly with the concomitant decrease in ABA (r = -0.586, P = 0.022). CONCLUSIONS: Phytoestrogen treatment interferes with HPT axis in CaP patients by inducing testicular resistance to LH and compensated hypogonadism.

Administration, Oral↗
PubMed2005

Characterization and quantification of soy isoflavone metabolites in serum of renal transplanted patients by high-performance liquid chromatography/electrospray ionization mass spectrometry.

During a dietary intervention study on 16 renal transplanted patients, in which 25 g/day of animal proteins were replaced with 25 g of soy proteins, the metabolic profile of soy isoflavones in serum was characterized. This paper describes a reliable and fast liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) method, in negative ion mode, allowing the characterization and simultaneous quantification of several soy isoflavone metabolites. Six metabolites were identified and quantified: daidzein ([M-H](-) at m/z 252.8), dihydrodaidzein (DHD, [M-H](-) at m/z 254.8), equol ([M-H](-) at m/z 240.9), O-desmethylangolensin (O-DMA, [M-H](-) at m/z 256.8), genistein ([M-H](-) at m/z 268.8), and dihydrogenistein (DHG, ([M-H(+)](-) at m/z 270.8). Quantification was assessed using two deuterated internal standards, D(3)-daidzein and D(4)-genistein. This method permitted a limit of quantification (LOQ, S/N = 10) and a limit of detection (LOD, S/N = 3) of 0.05 microM and 0.005 microM for all analytes, except for genistein, where the LOQ and LOD were 0.005 microM and 0.001 microM, respectively. The linearity ranges were from 0.005 to 1.5 microM for genistein, from 0.05 to 1.5 microM for DHG, and from 0.05 to 0.7 microM for the other metabolites. The relative standard deviations (RSDs) were between 0.19% and 13.9% at the LOQ concentration for all metabolites, and between 0.6% and 4.8% at the maximum concentration. On the basis of the results obtained in the dietary intervention study, it was possible to split the patients into five groups characterized by different metabolic pathways.

Adult↗
PubMed1998

Antioxidant activities of isoflavones and their biological metabolites in a liposomal system.

Genistein and daidzein, the two major soy isoflavones, principally occur in nature as their glycosylated or methoxylated derivatives, which are cleaved in the large intestine to yield the free aglycones and further metabolites. The objective of this study was to compare the antioxidant activities of genistein and daidzein with their glycosylated and methoxylated derivatives and also those of their human metabolites. The abilities of these compounds to inhibit lipid peroxidation in a liposomal system were evaluated using fluorescence spectroscopy, and structural criteria that enhance antioxidant activity were established. The peroxidation initiators employed in the study were Fe(II) and Fe(III) metal ions and aqueous-phase, azo-derived peroxyl radicals. Both the parent isoflavonoids and their metabolites were more effective at suppressing metal-ion-induced peroxidations than the peroxyl-radical-induced peroxidation. Antioxidant activities for the isoflavone metabolites were comparable to or superior to those for the parent compounds. Equol and its 4-hydroxy and 5-hydroxy derivatives were the most potent antioxidants in the study, suggesting that absence of the 2, 3-double bond and the 4-oxo group on the isoflavone nucleus enhances antioxidant activity. Additionally, the number and position of hydroxyl groups were determining factors for isoflavonoid antioxidant activity, with hydroxyl substitution being of utmost importance at the C-4' position, of moderate importance at the C-5 position, and of little significance at the C-7 position.

Amidines↗
PubMed1998

Antioxidant efficacy of phytoestrogens in chemical and biological model systems.

Phytoestrogens (PEs) are diphenolic compounds from plants which can bind to estrogen receptors and have estrogen and antiestrogen effects in man and animals. Like other plant phenolics, PEs may have antioxidant properties through hydrogen/electron donation via hydroxyl groups. They might therefore act as free radical scavengers and inhibit development of coronary heart disease and cancers. The hydrogen-donating ability of a range of phytoestrogens was assessed using electron spin resonance spectroscopy, the ferric-reducing ability of plasma assay, and the Trolox equivalent antioxidant capacity. In addition, the ability of compounds to inhibit lipid peroxidation was examined in vitamin E-deficient liver microsomes. Genistein had the highest activity of the isoflavones; however, the isoflavones were relatively poor hydrogen donors compared with the other estrogenic compounds examined. Coumestrol and equol were more effective antioxidants than genistein but had relatively limited activity in comparison with Trolox. The only estrogenic compound with significant antioxidant activity was kaempferol which is better known as a dietary antioxidant than a phytoestrogen. As the concentrations of PEs used in this study exceed the estimated serum concentrations, their relatively poor antioxidant ability in vitro may indicate little significance as antioxidants in vivo.

Animals↗
PubMed1995

Isotope dilution gas chromatographic-mass spectrometric method for the determination of unconjugated lignans and isoflavonoids in human feces, with preliminary results in omnivorous and vegetarian women.

We describe an isotope dilution gas chromatographic-mass spectrometric (GC/MS) method for the identification and quantitative determination of the lignans enterolactone, enterodiol, and matairesinol and the isoflavonoids daidzein, equol, O-desmethylangolensin, and genistein in feces. Following the addition of deuterated internal standards for all compounds, the feces samples are extracted and purified in several ion exchange chromatographic steps. Following formation of trimethylsilyl ethers, the samples are analyzed by combined capillary column GC/MS in the selective ion monitoring mode and corrected for all losses during the procedure using the deuterated internal standards. Results on the reliability of the method and values for nine Finnish omnivorous and nine vegetarian women are presented.

4-Butyrolactone↗
PubMed1986

Determination of urinary lignans and phytoestrogen metabolites, potential antiestrogens and anticarcinogens, in urine of women on various habitual diets.

Recently two groups of compounds with diphenolic structure, the lignans and the isoflavonic phytoestrogens, were detected and identified in human urine and other biological fluids. These compounds are of great biological interest because they exhibit both in vitro and in vivo weak estrogenic and sometimes also antiestrogenic activities and many plant lignans have been shown to have anticarcinogenic, antiviral, antifungal and other interesting biological effects. The compounds found in relatively large amounts (10-1000 times more than estrogens) in urine are modified by intestinal bacteria from plant lignans and phytoestrogens, which are present in fiber-rich food such as grain and beans. They bind with low affinity to estrogen receptors and preliminary results suggest that they may induce production of sex hormone binding globulin (SHBG) in the liver and in this way may influence sex hormone metabolism and biological effects. Five compounds, the lignans enterolactone (Enl), enterodiol (End) and the isoflavonic phytoestrogen metabolites daidzein (Da), equol (Eq) and O-desmethylangolensin (O-Dma) were measured in urine by gas chromatography-mass spectrometry (selected ion monitoring) using deuterated internal standards in 5 groups of women (total number 53). The members of three dietary groups (omnivores, lactovegetarians and macrobiotics) were living in Boston and of two groups in Helsinki (omnivores and lactovegetarians). Until now measurements have been carried out in 94 72-h samples. The highest mean excretion of the most abundant compound, enterolactone, was found in the macrobiotic group and the lowest in the omnivoric groups. Total mean 24-h excretion of enterolactone was 17,680 nmol in the macrobiotics, 4,170 nmol in the Boston lactovegetarians, 3,650 nmol in the Helsinki lactovegetarians, 2,460 nmol in the Helsinki omnivores and 2,050 nmol in the Boston omnivores. The other diphenols followed approximately the same pattern. In an earlier study the lowest excretion of enterolactone (1,040 nmol/24 h) was found in a group of postmenopausal apparently healthy breast cancer patients living in Boston. It is concluded that further studies are necessary to elucidate the possible role of these compounds in cancer and other diseases. However, the evidence obtained until now seems to justify the conclusion that these compounds may be among the dietary factors affording protection against hormone-dependent cancers in vegetarians and semivegetarians.

Animals↗
PubMed1987

Effect of dietary components, including lignans and phytoestrogens, on enterohepatic circulation and liver metabolism of estrogens and on sex hormone binding globulin (SHBG).

A brief account of our present knowledge on the enterohepatic metabolism of estrogens and on the origin, metabolism and biological effects of mammalian lignans and phytoestrogens is undertaken. Furthermore, recently published results on the effects of dietary fiber, fat and carbohydrates on estrogen metabolism are reviewed. New preliminary results are presented on quantitative assays of lignans and phytoestrogens in urine of women belonging to various dietary and population groups and in a group of chimpanzees. The highest values of lignans and phytoestrogens were found in the non-human primates, and in macrobiotic, lactovegetarian and Japanese women, all groups considered having a low risk for the development of breast and other hormone-dependent cancer. New results on correlations between intake of various fibers, lignan and phytoestrogen excretion and plasma levels of estrogens, free testosterone and SHBG in women are presented. There is a significant positive correlation between the intake of fiber and urinary excretion of lignans and phytoestrogens, and the concentration of plasma SHBG. Fiber intake and urinary excretion of lignans and equol correlated negatively with plasma percentage free estradiol. Enterolactone excretion correlated negatively with plasma free testosterone. It is concluded that dietary macro- and micronutrients seem to play an important role in estrogen metabolism.

Animals↗
PubMed1990

Interaction of phytoestrogens and other environmental estrogens with prostaglandin synthase in vitro.

The phytoestrogens daidzein, genistein, equol and coumestrol were found to stimulate microsomal prostaglandin H synthase (PHS) in vitro in a concentration-dependent manner when PHS-activity was measured by arachidonic acid-dependent oxygen uptake. These compounds were co-oxidized by PHS and the conversion of parent compounds was measured by HPLC analysis. The stimulation of PHS-cyclooxygenase by these compounds was partially reversed at high concentrations probably due to their antioxidant properties causing inhibition. In contrast, the monomethyl ethers of daidzein and genistein, formononetin and biochanin A, had little or weakly inhibitory effect on PHS, and appear to be no or poor co-substrates for PHS. Compared to the equine estrogen equilin, its metabolite d-equilenin was poorly metabolized by PHS and inhibited rather than stimulated PHS-cyclooxygenase activity in vitro. The resorcylic acid lactones zearalenone and zeranol, on the other hand, were surprisingly good inhibitors of PHS-cyclooxygenase. Furthermore, zeranol inhibited both the arachidonic acid and the hydrogen-peroxide-dependent oxidation of DES in contrast to indomethacin which inhibited only cyclooxygenase-dependent co-oxidation of DES. The results of this in vitro study are discussed in the context of data on synthetic and steroidal estrogens and support the idea that PHS-activity may be modulated by interaction with certain estrogenic compounds.

Cyclooxygenase Inhibitors↗
PubMed1995

Effect of diet on lignans and isoflavonoid phytoestrogens in chimpanzees.

Diphenolic compounds belonging to the classes of lignans and isoflavonoids have been identified in urine of man and animals, including the chimpanzee. Some of these compounds, formed by intestinal bacteria from plant lignans and phytoestrogens, have been shown in animal studies to exhibit biological activities that suggest they could function as cancer-protective compounds. The effect of diet on urinary excretion of these compounds in the adult male chimpanzee has been studied. It was found that the chimpanzees consuming their regular food excreted large amounts of the isoflavonoid phytoestrogens, equol (mean +/- SE) (127.5 +/- 34.0 nmol/mg cr.) and daidzein (20.7 +/- 9.0 nmol/mg cr.) and the lignan, enterolactone (14.1 + 3.5 nmol/mg cr.). Small amounts of the lignan, enterodiol, (0.4 +/- 0.2 nmol/mg cr.) were also excreted. On all other four test diets (high protein, high carbohydrate, high vegetable, and high fat), the excretion was less, particularly on a high fat diet where the excretion of all diphenolic compounds was reduced by more than 90% to a level observed in omnivorous human subjects or women with breast cancer. These results suggest that diet profoundly influences the excretion of both animal lignans and phytoestrogens in urine. Because non-human primates are particularly resistant to mammary and genital carcinoma on estrogen treatment, the present data suggest that the very high levels of phytoestrogens and lignans as found during exposure to the regular diet may partially account for why these primates are so resistant to hormonal manipulations to induce cancer.

Animals↗
PubMed1996

Interactions between phytoestrogens and human sex steroid binding protein.

The interactions of human Sex steroid binding protein (SBP) and the lignans [Nordihydrogaiaretic acid (NDGA) enterolactone (Ent), enterodiol (End)] and isoflavonoid phytoestrogens [Equol (Eq), diazein Dad), genistein (Gen)] were studied. The phytoestrogens had different dose-dependent inhibitory effects on steroid binding by SBP. Their relative efficiencies were: Ent> or = NDGA = Eq > Gen for displacing E2 and Eq > Ent > NDGA > Gen for displacing T. End and Dad were much less active. Scatchard analysis suggested that NDGA had similar non- competitive effects on T and E2 binding by reducing the number of binding sites without changing the association constants. But Eq seemed to inhibit E2 binding non-competitively and T binding competitively. NDGA binding to SBP reduced the immunorecognition of SBP by monospecific anti-SBP antibodies, suggesting that NDGA changed SBP immunoreactivity. Unlike NDGA, Eq binding to SBP caused no immunological changes in SBP, indicating qualitative differences in the effects of the lignan and isoflavonoid. Our results indicate that phytoestrogens may modulate the SBP activity and so influence the role of this protein in the delivery of hormonal information to sex steroid-dependent cells.

4-Butyrolactone↗