Concentrations Of Daidzein Research Articles

Antioxidant properties of aqueous and methanol soy extracts in minced trout muscle

Antioxidant capacity of freeze-dried aqueous and methanolic extracts of soy protein isolate (SPI) and soybean meal (SBM) were assessed by 2, 2′-Diphenyl-1-picrylhydrazyl (DPPH) assay and total phenolic content (TPC). Caffeic and chlorogenic acids in liquid aqueous extracts, and genistein and daidzein in liquid methanolic extracts were measured by HPLC. Freeze-dried extracts were applied (1000 and 4000 μg/g) to trout mince and TBARS formation monitored during 14 days refrigerated storage. SBM aqueous extracts-treated mince (4000 μg/g) had significantly lower ( P < 0.05) TBARS than all other treatments. SPI methanolic extract had the highest TPC (100 mg chlorogenic acid equivalents/100 g extract) and genistein and daidzein contents. SPI aqueous extracts had the highest chlorogenic acid (280 μg/g) while SBM aqueous extracts had the highest caffeic acids content (484 μg/g). SPI had the best in vivo antioxidant profile. SBM extracts were most effective at retarding lipid oxidation in refrigerated trout mince.

Optimizing Time and Temperature of Enzymatic Conversion of Isoflavone Glucosides to Aglycones in Soy Germ Flour

Five factors (enzyme concentration, substrate concentration, pH, incubation temperature, and incubation time) were initially screened for the conversion of isoflavone glucosides to aglycones in soy germ flour. The incubation temperature/time most significantly affected aglycone yield; subsequently, a full 5 (35, 40, 45, 50, and 55 °C) × 6 (1, 2, 3, 4, 5, and 6 h) factorial design and response surface methodology were employed to attain an optimal incubation time/temperature condition. The optimum condition producing soy germ flour with a high concentration of daidzein, glycitein, and genistein was as follows: soy germ flour:deionized water (1:5, w/v), β-glucosidase at 1 unit/g of soy germ flour, pH 5, and incubation temperature/time of 45 °C/5 h. Under this optimal condition, most isoflavone glucosides were converted to aglycones with daidzein, glycitein, and genistein of ≥ 15.4, ≥ 6.16, and ≥ 4.147 μmol/g, respectively. In contrast, the control soy germ flour contained 13.82 μmol/g daidzin, 7.11 μmol/g glycitin, 4.40 μmol/g genistin, 1.56 μmol/g daidzein, 0.52 μmol/g glycitein, and 0.46 μmol/g genistein.

Urinary isoflavone phytoestrogens in German children and adolescents – A longitudinal examination in the DONALD cohort

In light of concerns about hormonally active agents, it is important to assess human exposure to such compounds, especially in children as a susceptible subgroup. Estrogenic plant constituents are present in the human diet in varying levels, in particular the isoflavones daidzein (DAI) and genistein (GEN). We aimed to examine age-dependent and secular trends in phytoestrogen exposures and to investigate equol (EQ) excretion of German children using biomarker analysis in 24-h urine samples from a longitudinally designed study. The concentrations of DAI, its metabolite EQ and GEN were determined by GC-MS analysis in 24-h urines (510 samples) collected between 1985 and 2000 in 90 (47 boys) German children (6-18 years old), who are participants in the Dortmund Nutritional and Anthropometric Longitudinally Designed study. The results from the urinary biomarker analysis indicate isoflavone exposures at quite variable levels in German children: Analyte concentrations in over 500 urine samples cover the range reported previously in adults on typical German diet and with soy intake. EQ, the DAI metabolite produced by the gastrointestinal microflora, was detected in a high fraction of all samples, with 28/90 children (31%) excreting EQ in all their urines, and 62/90 children (68%) in at least one sample. Interestingly, when multiple urines obtained from individuals at different ages (6-18 years) were analyzed, EQ formation did not appear to be a constant trait over time. When stratified by sex, DAI, EQ and GEN concentrations (ng/mL) in urines and excretion rates (μg/day) were similar in boys and girls. Total isoflavone excretion rates (μg/day) increased during childhood (6-12 years) (p=0.02) and were constant during adolescence (13-18 years) (p=0.6). No clear trend for changes in dietary isoflavone exposure over the total study period was seen (p=0.7). In conclusion, biomarkers in urine of German children and adolescents indicate a frequent, but widely variable dietary isoflavone intake and suggest no secular increase (1985-2000) in the exposure to isoflavone phytoestrogens among German children and adolescents.

Effects of Riboflavin Photosensitization on Daidzein and Its Photosensitized Derivatives

Photosensitized compounds from daidzein were studied in a riboflavin model system under visible light irradiation by high-performance liquid chromatography (HPLC). As the period of light irradiation increased, concentration of daidzein decreased significantly (P < 0.05) and new peaks of daidzein derivatives were observed and changed during photosensitization. Three new peaks from photosensitized daidzein were tentatively identified as 7-, 3', 4'-trihydroxyisoflavone (or 3'-hydroxydaidzein) and 2 dimmers of daidzein by a combination of HPLC-mass spectrometry (MS) and retention times of standard compounds by HPLC. Addition of sodium azide and removal of headspace oxygen treatment affected the formation of newly formed peaks. The type I pathway of riboflavin photosensitization played more important roles than type II pathways on the formation of daidzein derivatives. Practical Application: Isoflavones are important phytochemicals found in soy foods. Generally, many foods containing soy ingredients are displayed under visible light irradiation. Also, riboflavin can be found in many foods containing vegetables. The results of this study can be used to understand the stability and changes of isoflavone aglycones in soy and soy-based foods under visible light irradiation.

Profiles of Phytoestrogens in Human Urine from Several Asian Countries

Intake of a diet rich in phytoestrogens has been associated with a decreased risk for hormone-dependent cancers in humans. Biomonitoring of phytoestrogens in human urine has been used to assess the intake of phytoestrogens. Although studies have reported phytoestrogen levels in urine specimens from the United States and Japan, little is known of human intake of phytoestrogens in other Asian countries. In this study we determined the concentrations of seven phytoestrogens, namely, enterolactone, enterodiol, daidzein, equol, O-desmethylangolensin (O-DMA), genistein, and coumestrol, in 199 human urine samples from three Asian countries, Vietnam (Hanoi and Ho Chi Minh), Cambodia (Phnom Penh), and India (Chennai and Kolkata), using a simple, sensitive, and reliable liquid chromatography (LC)-tandem mass spectrometry (MS/MS) method. The residue levels of phytoestrogens in urine samples from the three Asian countries were compared with the concentrations in 26 urine samples from Japan (Ehime) and 16 urine samples from the United States (Albany), analyzed in this study. Among the phytoestrogens analyzed, isoflavones such as daidzein and genistein were predominant in urine samples from Vietnam; samples from Cambodia and India contained higher concentrations of enterolactone than isoflavones. Urinary concentrations of isoflavones in samples from Hanoi, Vietnam, were notably higher than the concentrations in samples from Cambodia, India, and the United States and similar to the concentrations in samples from Japan. The lowest concentrations of daidzein and the highest concentrations of enterolactone were found in urine samples from India. Concentrations of equol and O-DMA, which are microbial transformation products of daidzein (produced by gut microflora), were notably high in urine samples from Hanoi, Vietnam. The ratios of the concentration of equol or O-DMA to that of daidzein were significantly higher in samples from Hanoi than from Japan, indicating high biotransformation efficiency of daidzein by the population in Hanoi. High concentrations of equol, in addition to isoflavones, in urine have been linked to reduced breast cancer risk in previous studies, and, thus, the Vietnamese population may have potential protective effect against breast cancer. This study suggests that the dietary intake and profiles of phytoestrogens vary considerably, even among Asian countries.

위도가 다른 재배지역에서 생육한 검정콩의 안토시아닌 및 이소플라본 함량 변이

This experiment was conducted to investigate the variation of anthocyanin, and isoflavone contents in five cultivars and two lines of Korean domestic black soybeans grown at different latitudinal locations, a high latitude, Suwon (16'N) and a low latitude, Milyang (30'N). Delphinidin-3-glucoside (D3G) contents of anthocyanin in Geomjeongkong # 3 and Ilpumgeomjeongkong, cyanidin-3-glucoside (C3G) content in Milyang # 113, petunidin-3-glucoside (Pt3G) contents in Milyang # 113, and Ilpumgeomjeongkong, and total anthocyanins in Milyang # 113 were highest among the seven black soybean cultivars and lines. D3G, C3G, and total anthocyanins in Geomjeongkong # 3, C3G, and total anthocyanins in Ilpumgeomjeongkong grown at high latitude were higher compared to low latitude. Daidzein, glycitein, genistein, and total isoflavone contents in Geomjeongkong # 4 were highest among the seven cultivars and lines. Daidzein contents of isoflavone in Geomjeongkong # 3, Milyang # 112, and Milyang # 113 grown at high latitude were higher compared to low latitude. Glycitein contents in Geomjeongkong # 3, and # 4 grown at high latitude were higher compared to low latitude, while it in Milyang # 113 grown at low latitude was higher compared to high latitude. Genistein contents in most black soybeans except Milyang # 113, and total isoflavone contents in Geomjeongkong # 4 and Cheongjakong grown at low latitude were higher compared to high latitude. The variations of anthocyanin except Pt3G and isoflavone contents seemed to be affected by environmental conditions like different latitude than the genotype because they showed the significant interaction between cultivars and locations.

Suppression of Colonic Aberrant Crypt Foci by Soy Isoflavones Is Dose-Independent in Dimethylhydrazine-Treated Rats

The potential of soy isoflavones (SIs) to reduce colon cancer has been investigated in animal models. These studies have found that outcomes are variable and depend on SI dose. The present study investigated dose-response effects of SIs on colon carcinogenesis in a chemically induced rat cancer model. Sprague-Dawley male rats were injected with 1,2-dimethylhydrazine (DMH) and were provided experimental diets that contained 0, 10, 50, 150, or 500 mg of SI aglycones/kg of diet for 12 weeks. Plasma concentrations of genistein, daidzein, and equol were determined using time-resolved fluoroimmunoassay. Plasma concentrations of these SIs tended to increase in a dose-dependent manner in DMH-treated rats. The numbers of aberrant crypt foci (ACF) and the expression of cyclooxygenase-2 (COX-2) proteins of colons were significantly decreased in the SI-fed groups compared with the control group; however, suppression was not dose-dependent. Furthermore, there were no significant correlations between plasma SI concentrations and ACF or COX-2 expression. Increased SI intake and increased plasma levels of SIs and metabolites were not associated with tissue levels of lipid peroxidation. We conclude that dietary supplementation of SIs suppresses DMH-induced ACF formation and COX-2 expression in a dose-independent manner.

Isoflavones from Phytoestrogens and Gastric Cancer Risk: A Nested Case-Control Study within the Korean Multicenter Cancer Cohort

The role of soybean products in gastric cancer risk is not clear in epidemiologic studies due to measurement error from dietary intake questionnaires and due to different degrees of bias according to study design. To examine the association between soybean products and gastric cancer risk, we measured phytoestrogen biological markers in a nested case-control study. The study population was composed of 131 cases and 393 matched controls within the Korean Multicenter Cancer Cohort. The concentrations of the four biomarkers in the plasma samples were measured using time-resolved fluoroimmunoassay. Conditional and unconditional logistic regression models were used to compute the odds ratio (OR) and 95% confidence intervals (CI). Median plasma concentrations of genistein (229 nmol/L for controls, 181.8 nmol/L for cases; P=0.07) and daidzein (131.2 nmol/L for controls, 80.5 nmol/L for cases; P=0.04) in cases were lower than in controls, whereas equol concentrations were similar. Compared with the reference group, gastric cancer risk decreased in the highest groups for genistein (OR, 0.54; 95% CI, 0.31-0.93) and daidzein (OR, 0.21; 95% CI, 0.08-0.58). Higher equol concentrations were associated with a decreased risk for gastric cancer (OR, 0.50; 95% CI, 0.27-0.90). The combination of the highest concentrations for each isoflavone category was associated with a 0.09-fold decreased risk for gastric cancer compared with the combination of the lowest concentrations for each category. There was no association between plasma lignan concentrations and gastric cancer. High serum concentrations of isoflavones were associated with a decreased risk for gastric cancer. These results suggest a beneficial effect of high soybean product intake for gastric cancer risk.

Bone mineral density in US adults in relation to urinary isoflavone excretion: secondary analysis using the National Nutrition and Health Examination Survey (NHANES) data

The NHANES provides a rich data source to efficiently evaluate correlates of health outcomes. Analysis of health in relation to objective measures of soy intake, such as urinary isoflavone concentrations, is challenged by differences in host intestinal bacterial profile. Some, but not all, individuals harbor bacteria capable of metabolizing the isoflavone daidzein to equol and O‐desmethylangolensin (ODMA). To assess the impact of controlling for daidzein excretion, associations of categorical and continuous measures of urinary equol, ODMA, daidzein, equol:daidzein, and ODMA:daidzein with bone mineral density (BMD) were evaluated in three NHANES data releases that were combined (1999–2004). Age‐ and sex‐adjusted total BMD in 3889 adults was positively associated with increasing quartiles of ODMA:daidzein (p=0.02) and ODMA concentration (p=0.01), but not with continuous ODMA:daidzein (p=0.38) and not as strongly with continuous ODMA concentration (p=0.08). BMD was positively associated with equol concentration (p&lt;0.01), but not as strongly with quartiles of equol concentration (p=0.06). BMD was not associated with daidzein concentration or equol:daidzein. Additional analyses will evaluate BMD in relation to urinary isoflavone measures stratified by sex and race/ethnicity groups, and with all analyses stratified by categories of isoflavone intake calculated from the dietary interview.

Disposition of soy isoflavones in normal human breast tissue

Despite decades of research on the relation between soy and breast cancer, questions regarding the absorption, metabolism, and distribution of isoflavones in breast tissue largely remain unanswered. We evaluated the potential health effects of isoflavone consumption on normal breast tissue; isoflavone concentrations, metabolites, and biodistribution were investigated and compared with 17beta-estradiol exposure. In this dietary intervention study, healthy women were randomly allocated to a soy milk (n = 11; 16.98-mg genistein and 5.40-mg daidzein aglycone equivalents per dose), soy supplement (n = 10; 5.27-mg genistein and 17.56-mg daidzein aglycone equivalents per dose), or control (n = 10) group. After a run-in period > or = 4 d, 3 doses of soy milk or soy supplements were taken daily for 5 d before an esthetic breast reduction. Blood and breast biopsies were collected during surgery and analyzed with liquid chromatography-tandem mass spectrometry. After soy administration, genistein and total daidzein concentrations, which were expressed as aglycone equivalents, ranged from 135.1 to 2831 nmol/L and 105.1 to 1397 nmol/L, respectively, in hydrolyzed serum and from 92.33 to 493.8 pmol/g and 22.15 to 770.8 pmol/g, respectively, in hydrolyzed breast tissue. The major metabolites identified in nonhydrolyzed samples were genistein-7-O-glucuronide and daidzein-7-O-glucuronide, with an overall glucuronidation of 98%. Total isoflavones showed a breast adipose/glandular tissue distribution of 40:60, and their mean (+/-SEM) derived 17beta-estradiol equivalents toward estrogen receptor beta were 21 +/- 4-fold and 40 +/- 10-fold higher than the 17beta-estradiol concentrations in adipose (0.283 +/- 0.089 pmol/g, P < 0.001) and glandular (0.246 +/- 0.091 pmol/g, P = 0.001) fractions, respectively. After intake of soy milk and soy supplements, isoflavones reach exposure levels in breast tissue at which potential health effects may occur.

Seasonal changes in temperature and precipitation influence isoflavone concentration in short-season soybean

Future soybean [ Glycine max (L.) Merr.] cultivars with elevated or reduced concentrations of isoflavones may be required to satisfy the food market. Climate influences isoflavone concentration making their prediction problematic. Our research examined the associations between precipitation and temperature during a growing season with the isoflavone concentration in the harvested seed. We grew 14 cultivars across 12 years, at one location and calculated climate parameters for readily identifiable growth stage intervals (GSI). We correlated the climate parameters within each GSI with seed daidzein, genistein and total isoflavone (TIF) concentrations. We found that cumulative precipitation from the mid-vegetative to the flowering period was correlated with daidzein and TIF concentration. Mean daily average T during early vegetative development was positively correlated with daidzein and TIF concentration and this was largely a result of higher minimum daily T. Accumulated heat stress T greater than 27 °C during seed development was significantly correlated with a reduction in genistein and TIF, but not daidzein concentration. Accumulated cold stress T's less than 20, 15 and 17 °C during seedling emergence were significantly correlated with higher seed daidzein, genistein and TIF concentrations, respectively in all short-season cultivars tested. Cold stress T during seedling emergence could be used to predict seasonal changes in isoflavone concentrations.

Comparison of Puerariae Radix and Its Hydrolysate on Stimulation of Hyaluronic Acid Production in NHEK Cells

Hyaluronic acid (HA) is present in high concentrations in the intercellular spaces of the epidermis and the connective tissues of the dermis. It is associated with many beneficial biological activities including water retention, maintenance of various cellular functions, and skin homeostasis. Puerariae Radix (PR), a Chinese herb and a popular food in Asia, is used for various medicinal purposes including anti-hypertension, anti-angina pectoris and anti-dipsotropic. PR is rich in isoflavone glycosides like genistin and daidzin as soya. In this study, Bifidobactericum breve CCRC 14061 and CCRC 11846 were used for the fermentation of PR; moreover, acid was used to hydrolyze PR decoction. Genistein and daidzein in the hydrolysate were determined by HPLC. The HA production in normal human epidermal keratinocytes (NHEK) was measured after 48 hours incubation with PR and its hydrolysate, respectively. HA was assayed by enzyme-linked immunosorbent assay (ELISA), and retinoic acid was used as the positive control. After fermentation with Bifidobactericum breve, the contents of daidzein and genistein were increased 785% and 1,010% by CCRC 14061, and 192% and 406% by CCRC 11846, respectively, whereas after acid hydrolysis, only daidzein was increased by 990%. The production of HA in NHEK was increased after incubation with the fermentation product of CCRC 14061, acid hydrolysate, PR decoction and retinoic acid (22+/- 0.2%), whereas no increase of HA concentration was found after incubation with the fermentation product of CCRC 11846. Furthermore, the PR hydrolysate stimulated the HA production of NHEK, and the effect was dose-dependent (18.6%-83.9%). In conclusion, PR preparations would stimulate HA production in NHEK cells which might be used as a new cosmetic ingredient in moisturizers and an anti-aging agent.

Differential effects of whole soy extract and soy isoflavones on apoptosis in prostate cancer cells

Previous studies have suggested that soy isoflavones exert anticarcinogenic effects against prostate cancer. We propose that soy extracts, containing a mixture of soy isoflavones and other bioactive components, would be a more potent chemo-preventive agent than individual soy isoflavones. We compared the apoptotic effects of whole soy extracts and individual soy isoflavones, genistein and daidzein, on prostate cancer cells. The soy extract contained 50% w/w of total isoflavones with approximately 1:5.5:3.5 ratios of genistin, daidzin and glycitin, respectively. Benign prostate hyperplasia (BPH-1), LnCap and PC3 cells were treated with varying concentrations of soy extract, genistein or daidzein and analyzed for cell cycle alterations and induction of apoptosis. At equal concentrations (25 micromol/L), soy extract induced a significantly higher percentage of cells undergoing apoptosis than genistein or daidzein (P < 0.001). No significant changes in cell cycle arrest or apoptosis were observed in non-cancerous BPH-1 cells treated with soy extract, suggesting that the effects of soy extract may be tumor cell specific. On the contrary, both genistein and daidzein induced apoptosis in BPH-1 cells, suggesting that individual isoflavones may have cytotoxicity in non-cancerous cells. Soy extracts also increased Bax expression in PC3 cells, but no significant changes in nuclear factor kappaB (NF kappaB) activation were detected, suggesting that the induction of apoptosis was independent of the NF kappaB pathway. Food products that bear a combination of active compounds may be more efficacious and safer as chemo-preventive agents than individual compounds. This 'whole-food'-based approach is significant for the development of public health recommendations for prostate cancer prevention.

Flaxseed Lignans Promoted the Growth of Skeletal Muscle in Male Rats and Its Possible Mechanism

This study was aimed to determine whether flaxseed lignans could affect the growth of skeletal muscle in male animals and its possible mechanisms. The impact of flaxseed lignans on the skeletal muscle in male rats was determined in vivo. Flaxseed lignans (50 ppm) and daidzein (5 ppm) were added into the basal diets, respectively. The concentrations of serum lignans and daidzein were measured by high performance liquid chromatography (HPLC), and the serum growth hormone and testosterone (T) levels were analyzed by radioimmunoassay (RIA), and the expression of estrogen receptor β (ER β) in the soleus muscle and hypothalamus were determined by reverse-transcription polymerase chain reaction (RT-PCR). Flaxseed lignans and daidzein could significantly improve the feed efficiency and facilitate the weight gain of the femoral muscle in male rats. The ratio of RNA to DNA in the muscles and serum T levels was remarkably increased, whereas, the urea nitrogen concentrations were significantly decreased by flaxseed lignan and/or its metabolites and daidzein. Meanwhile, the expression of ER β in soleus muscle and hypothalamus were both upgraded by the two phytoestrogens. Flaxseed lignan promoted the growth of male rats, and it might be by regulating serum T levels by binding to ER β in the hypothalamus. In turn, it depressed the catabolism of protein and promoted the hypertrophy of skeletal muscle cells.

Isoflavone 비배당화 및 항산화 활성을 지닌 Lactobacillus plantarum YS712의 선발

Lactic acid bacteria (LAB) are typical probiotic microbes that are used in various industries including fermented foods, feed additives, and pharmaceuticals. The purpose of this study was to compare the ability of isoflavone biotransformation and antioxidative activity of 17 LAB. Six strains including the Lactobacillus species exhibited a 100% hydrolysis rate for daidzein during fermentation. The content of total genistein in soymilk fermented with these strains was . The DPPH (1, 1-diphenyl-2-picrylhydrazyl) radical scavenging ability of the LAB was widely variable and ranged from 23-78%. A selected strain was isolated from kimchi and the strain was identified as Lactobacillus plantarum ssp. through the API carbohydrate fermentation pattern and 16S rDNA profile. The strain exhibited excellent acid tolerance in an artificial gastric solution. L. plantarum YS712 showed high -glucosidase activity in fermentation. The concentration of genistein and daidzein in soymilk fermented with L. plantarum YS712 increased from 3.64 to and from 58.18 to , respectively. These results demonstrate the potential of L. plantarum YS712 as a probiotic culture that can be utilized in the manufacturing of fermentation foods and dietary supplements.

Enhancement of Aglycone, Vitamin K2 and Superoxide Dismutase Activity of Black Soybean through Fermentation with Bacillus subtilis BCRC 14715 at Different Temperatures

In the present study, the change in the content and activity of some functional constituents including aglycone, the bioactive form of isoflavone, vitamin K2, and superoxide dismutase (SOD) of black soybeans during their solid fermentation with Bacillus subtilis BCRC 14715 at different temperatures (35, 40, 45, and 50 degrees C) for 18 h was investigated. It was generally found that fermentation resulted in an enhancement of these constituents, regardless of fermentation temperature, while varying the fermentation temperature of black soybeans produced variations in the enhancement. The 50 degrees C -fermented black soybean showed the most marked increase in the content of daidzein and genistein aglycone. On the other hand, the highest SOD activity and vitamin K2 content were found in the black soybeans fermented at 45 and 40-45 degrees C, respectively. Thus functional properties of black soybeans can be further improved through fermentation with B. subtilis BCRC 14715.

Determination of Phytoestrogen Composition in Soybean Cultivars in Serbia

The growing clinical interest and use of soybean-based food products and extracts to increase dietary phytoestrogen intake have led to medical interest in the precise determination of the phytoestrogen composition of soybean products. We have analyzed the composition of these compounds in 20 domestic and introduced varieties of genetically non-modified soybean genotypes grown under the same agroecological conditions. The isoflavone content of soybeans cultivated in this region of Serbia has not been previously reported. The assays were performed, after extraction with methanol-water (8:2, v/v), by C18 reversed phase high-performance liquid chromatography coupled with photodiode array detection. The total phytoestrogen concentration was found to be between 2.24 and 3.79 mg g(-1) dry bean weight. The total concentration of daidzein and its derivatives ranged from 0.96 to 1.82 mg g(-1), total glyciteines from 0.34-0.53 mg g(-1), and all genistein derivatives from 0.86-1.67 mg g(-1) dry bean weight. Given the high biological potency of phytoestrogens and their metabolic conversion products, our data suggest that phytoestrogen content screening could be a useful tool in the selection of soybean genotypes with improved health promoting characteristics.

Isoflavone supplements stimulated the production of serum equol and decreased the serum dihydrotestosterone levels in healthy male volunteers

The aim of this study was to evaluate the effect of supplementing healthy men with soy isoflavones on the serum levels of sex hormones implicated in prostate cancer development. A total of 28 Japanese healthy volunteers (18 equol producers and 10 equol non-producers) between 30 and 59 years of age were given soy isoflavones (60 mg daily) supplements for 3 months, and the changes in their sex hormone levels were investigated at the baseline and after administration. The serum and urine concentrations of daidzein, genistein, and the levels of equol in the fasting blood samples and 24-h stored urine samples were also measured. All 28 volunteers completed the 3-month supplementation with isoflavone. No changes in the serum levels of estradiol and total testosterone were detected after 3-month supplementation. The serum levels of sex hormone-binding globulin significantly increased, and the serum levels of free testosterone and dihydrotestosterone (DHT) decreased significantly after 3-month supplementation. Among the 10 equol non-producers, equol became detectable in the serum of two healthy volunteers after 3-month supplementation. This study revealed that short-term administration of soy isoflavones stimulated the production of serum equol and decreased the serum DHT level in Japanese healthy volunteers. These results suggest the possibility of converting equol non-producers to producers by prolonged and consistent soy isoflavones consumption.

Determination of daidzein and genistein in soybean and its waste by matrix solid-phase dispersion extraction and HPLC

Matrix solid-phase dispersion (MSPD) extraction and HPLC have been used for determination of daidzein and genistein in Iranian soybean and its waste. For extraction of these compounds, the type of sorbent, the ratio of sorbent to sample, and the type and volume of elution solvent and its pH were studied. The best recoveries were obtained with a ratio 2:1 of silica gel to sample and 12 cm3 methanol at pH 3. Optimized mobile phase composition for HPLC analysis of these compounds was φ(H2O) = 0.45, φ(MeOH) = 0.54, φ(THF) = 0.01 adjusted to pH 4 by use of phosphate buffer. Limit of detection and linear dynamic range for daidzein and genistein were 0.016, 0.052, 0.016–132, and 0.052–146 μg/g. Recoveries of daidzein and genistein from soybean and its waste were 84–95%. Concentrations of daidzein in soybean and its waste were 39.1 and 22.2 μg/g, respectively; respective concentrations of genistein were 103.3 and 19.7 μg/g.

The effect of feeding soybean-derived phytoestogens on their concentration in plasma and milk of lactating dairy cows

The objective of this study was to determine the effect of dietary soybean phytoestrogens, daidzein and genistein, on yield and composition of milk and excretion of phytoestrogens and their metabolites into milk. The experiment was carried out on four lactating Holstein cows as replicated Latin square in a double reversal design. The experiment was divided into four periods of 42 days consisting of a 21-day preliminary period and a 21-day experimental period. Cows were divided into two groups. The control group (Group R) was fed a diet based on extruded rapeseed cake while the experimental group (Group S) received a diet containing extruded full-fat soybeans. Compared to Group R, in Group S the daily intake of daidzein and genistein was about 40 and 75 times higher, respectively. In the milk of Group S the concentration of daidzein and its metabolite equol was significantly higher (p < 0.001) and the concentration of genistein tended to be higher than in Group R. Total excretion of daidzein, genistein and equol in milk of Group S, being 384, 958 and 1300 μg/d, respectively, was higher than in Group R (285, 794 and 80 μg/d, respectively, p < 0.001). In Group S the concentration of daidzein, genistein and equol in plasma was also increased (p < 0.001).