Soy isoflavone aglycones are absorbed faster and in higher amounts than their glucosides in humans

Difference in Plasma Metabolite Concentration after Ingestion of Lemon Flavonoids and Their Aglycones in Humans

The concentrations of metabolites in human plasma after ingestion of flavanone glycosides (FG) and their aglycones (FA) in lemon were examined. FG consisting abundantly of eriocitrin were prepared from lemon peel and FA consisting abundantly of eriodictyol were prepared from FG by treatment with beta-glucosidase. Eriodictyol, homoeriodictyol, and hesperetin in plasma up to 4 h after ingestion of FG with water or FA with water by subjects were not detected in plasma of non-enzyme treatment but in plasma after treatment with beta-glucronidase and sulfatase. Metabolites in plasma after ingestion of FG and FA in humans were shown to exist as the glucuro- and/or sulfo-conjugates of eriodictyol, homoeriodictyol, and hesperetin. After ingestion of FA, the concentration of metabolites in plasma exhibited a high maximum peak at 1 h. The AUC (area under the blood concentration time curve) level of metabolites of FA was higher than that of FG. FA were suggested to be absorbed faster and in higher amounts than FG. The AUC of metabolites in subject plasma after ingestion of FG with flavonoid-depleted lemon juice was shown to change to a low level in comparison with that of FG with water. The maximum concentration peak of metabolites in plasma was faster at 0.5 h than FA with water but the AUC level was similar to FA with water, when subjects ingested FA with vodka (40%, ethanol). The absorption hour of FG and FA was shown to be affected by the co-existing solution.

Factors affecting the bioavailability of soy isoflavones in humans after ingestion of physiologically relevant levels from different soy foods

The precise role that isoflavones play in the health-related effects of soy foods, and their potential for adverse effects are controversial. This may be due in part to a lack of basic knowledge regarding their bioavailability and metabolism, particularly as it relates to the soy source. To date, there is little information concerning possible differences in the bioavailability of isoflavones derived from natural soy foods consumed at physiologically relevant intakes and whether age- or gender-related differences influence that bioavailability. In the current study of healthy adults [premenopausal (n = 21) and postmenopausal (n = 17) women and a group of men (n = 21)], we examined the effect of age, gender, and the food matrix on the bioavailability of isoflavones for both the aglycon and glucoside forms that are naturally present in 3 different soy foods, soy milk, textured vegetable protein, and tempeh. The study was designed as a random crossover trial so that all individuals received each of the 3 foods. The dose of isoflavones administered to each individual as a single bolus dose was 0.44 mg/kg body weight. Pharmacokinetic parameters were normalized to mg of each isoflavone ingested per kilogram body weight to account for differences in daidzein and genistein content between the diets. Serum isoflavone concentrations in all individuals and groups increased rapidly after the ingestion of each soy food; as expected, genistein concentrations exceeded daidzein concentrations in serum. In this small study, gender differences in peak concentrations of daidzein were observed, with higher levels attained in women. Consumption of tempeh (mainly isoflavone aglycon) resulted in higher serum peak levels of both daidzein (P < 0.001) and genistein (P < 0.01) and the associated area under the curve (P < 0.001 and P < 0.03, respectively) compared with textured vegetable protein (predominantly isoflavone glucosides). However, soy milk was absorbed faster and peak levels of isoflavones were attained earlier than with the other soy foods. Only 30% of the subjects were equol producers and no differences in equol production with age or gender were observed.

Soy extract has different effects compared with the isolated isoflavones on the proteome of homocysteine-stressed endothelial cells

Epidemiological studies suggest that soy consumption may provide a protection in the development and progression of atherosclerosis. It is under debate, however, whether the soy isoflavones or other compounds are the "active principle". As apoptosis is a driving force in the process of atherosclerosis, we tested whether a soy extract or a combination of the two predominant isoflavones genistein and daidzein, in concentrations as found in the extract, exert similar or different effects on apoptosis in EA.hy 926 endothelial cells after exposure to the endothelial stressor homocysteine. Plasma membrane disintegration and nuclear fragmentation served as relevant apoptosis markers. To assess whether the extract and the genistein/daidzein mixture differently affect cellular target proteins changed in amount by homocysteine treatment, proteome analysis was performed by two-dimensional gel-electrophoresis and peptide mass fingerprinting of regulated protein spots. Homocysteine induced apoptosis in the cells, and both extract and genistein/daidzein inhibited apoptosis to a comparable extent. Whereas the extract prevented for 10 proteins the changes in expression levels as caused by homocysteine, the genistein/daidzein mixture reversed the homocysteine effects on the proteome for 13 proteins. The cytoskeletal protein matrin 3 and a U5 snRNP-specific 40-kDa protein were the only protein entities where both extract and genistein/daidzein reversed the homocysteine-induced changes in a common way. In conclusion, our studies provide evidence that an isoflavone containing soy extract and isolated isoflavones, despite similar effects on inhibition of homocysteine-induced apoptosis in endothelial cells, affect a quite different spectrum of cellular target proteins.

Genistein blocks homocysteine-induced alterations in the proteome of human endothelial cells

Dietary isoflavones from soy are suggested to protect endothelial cells from damaging effects of endothelial stressors and thereby to prevent atherosclerosis. In search of the molecular targets of isoflavone action, we analyzed the effects of the major soy isoflavone, genistein, on changes in protein expression levels induced by the endothelial stressor homocysteine (Hcy) in EA.hy 926 endothelial cells. Proteins from cells exposed for 24 h to 25 microM Hcy alone or in combination with 2.5 microM genistein were separated by two-dimensional gel electrophoresis and those with altered spot intensities were identified by peptide mass fingerprinting. Genistein reversed Hcy-induced changes of proteins involved in metabolism, detoxification, and gene regulation; and some of those effects can be linked functionally to the antiatherosclerotic properties of the soy isoflavone. Alterations of steady-state levels of cytoskeletal proteins by genistein suggested an effect on apoptosis. As a matter of fact genistein caused inhibition of Hcy-mediated apoptotic cell death as indicated by inhibition of DNA fragmentation and chromatin condensation. In conclusion, proteome analysis allows the rapid identification of cellular target proteins of genistein action in endothelial cells exposed to the endothelial stressor Hcy and therefore enables the identification of molecular pathways of its antiatherosclerotic action.

High-performance liquid chromatography–tandem mass spectrometry for identification of isoflavones and description of the biotransformation of kudzu root

High-performance liquid chromatography-tandem mass spectrometry has been used to identify isoflavone aglycones and glycosides in kudzu root. Fourteen isoflavones were detected. Among these, six were identified by comparison with authentic standards. Tentative identifications of the other isoflavones are based on UV spectra, mass spectra of protonated and deprotonated molecules, and MS-MS data. Several are reported for the first time in kudzu root. The bioactivity and bioavailability of isoflavone aglycones are usually greater than those of their glycosides. To improve the bioavailability of kudzu root isoflavones, crude beta-glycosidases prepared from microbes were used to hydrolyze the isoflavone glycosides. Several MS modes are combined not only to identify the isoflavones in kudzu root, but also to describe the biotransformation of kudzu root isoflavone glycosides. It is also proved that crude beta-glycosidases have high selectivity toward the O-glycosides of isoflavones.

Optimizing dough proofing conditions to enhance isoflavone aglycones in soy bread

Native beta-glucosidase activity in soy bread can convert isoflavone glucosides to aglycones during proofing, and this study determined the time-temperature dependence of this process. Samples were taken every hour for 4 h during proofing at 22, 32, and 48 degrees C to determine beta-glucosidase activity and isoflavone profiles of the dough. After 1-2 h, the beta-glucosidase activity increased 43-84% achieving a plateau value at 22 degrees C but declining when proofed beyond 2 h at 32 degrees C and 48 degrees C. Large increases in aglycones and corresponding decreases in the simple glucosides were observed during proofing. The level of malonyl-glucosides decreased 3-15%, and acetyl-glucosides were fairly constant. The two higher temperatures drove more rapid conversion: 70-73% of simple glucosides in 2-4 h. The extent of conversion in the early proofing periods corresponded to beta-glucosidase activity. The optimum time-temperature protocol was 2 h at 48 degrees C resulting in a rapid, high conversion.

Acute, subchronic and chronic safety studies with genistein in rats

Genistein is a phytoestrogen that occurs naturally in the diet, especially in soy based foods. There is wide spread interest in phytoestrogens as chemopreventive agents for a variety of diseases and cancers based on epidemiologic evidence. Although soy, and its constituents such as genistein, have been consumed at high levels in several Asian populations without apparent adverse effects, concern has been raised about potential adverse effects due to the estrogenic and other activities. Safety studies with genistein were conducted in the Wistar rat including two acute studies, two subchronic (4 weeks and 13 weeks) and a chronic 52-week dietary admix study. In the acute studies, genistein had a low order of toxicity. In the three repeated dose safety studies at doses up to 500 mg/kg/day, genistein was well tolerated. In all of the studies, decreased food consumption and body weight gain were observed at 500 mg/kg/day. The main hematological findings were decreased red blood cell parameters at 500 mg/kg/day with a compensatory increase in reticulocytes. For clinical chemistry, with the exception of a slight increase in gamma glutamyl transferase in male and female rats at the high dose, there were a number of other minor changes considered not toxicologically significant. At necropsy, there were relatively few macroscopic changes; in the 52-week study, dilation of the uterus with fluid at the high dose and cysts of the ovaries in treated animals were observed. Organ weight changes in male rats at the high dose of 500 mg/kg/day included increased kidney, spleen, adrenal and testes weights and for females included, increased liver, kidney, spleen, ovary and uterus weights. After 4 and 13 weeks of treatment with genistein, there were no treatment related histopathologic findings. After 26 and 52 weeks of treatment, histological changes were seen in the female reproductive organs (ovaries and uterus), and in males (epididymides and prostate), and bone, kidneys, heart, liver and spleen in both sexes. After 52 weeks of treatment of males, vacuolation of the epididymal epithelium at 500 mg/kg/day and inflammation of the prostate were recorded at a higher incidence at 50 and 500 mg/kg/day. In females, cytological changes in the uterus, squamous metaplasia at 50 and 500 mg/kg/day and hyperplasia at 500 mg/kg/day were observed. Furthermore, hydrometra of the uterus and findings in the vagina consisting of anestric or diestrus vaginal mucosa with vaginal mucification, hyperplastic epithelium and multifocal cystic degeneration were noted at 500 mg/kg/day. Atrophy of the ovaries increased in severity in animals at 50 and 500 mg/kg/day. Osteopetrosis (hyperostosis) was observed in male and female rats at 50 and 500 mg/kg/day along with a compensatory increase in extramedullary hemopoiesis in the spleen; females were more affected than males. Hepatocellular hypertrophy and minimal bile duct proliferation were recorded at a higher incidence in animals at 500 mg/kg/day. It is concluded that almost all of the treatment related findings in these studies are related to the estrogenic properties of genistein as a phytoestrogen and would be expected to occur with a compound with estrogenic activity. The hormonally related changes were considered to be functional in nature and thus not adverse effects. Most of the findings in these studies were limited to the high dose of 500 mg/kg/day and were reversible. The few findings observed at 50 mg/kg/day were relatively minor and in view of the functional (hormonally mediated) nature of the effects, were considered not adverse effects. The increased incidence of minimal bile duct proliferation and slightly increased gamma glutamyl transferase are indicative of a mild hepatic effect at the high dose of 500 mg/kg/day. The no observed adverse effect level (NOAEL) of genistein is considered to be 50 mg/kg/day based on the presence of mild hepatic effects at the high dose of 500 mg/kg/day. The no observed effect level (NOEL) is considered to be 5 mg/kg/day based on the hormonally induced functional changes at higher doses.

Subchronic and chronic safety studies with genistein in dogs

Genistein is a phytoestrogen that occurs naturally in the diet, especially in soy-based foods. There is widespread interest in phytoestrogens as chemopreventive agents for a variety of diseases and cancers based on epidemiologic evidence. Although soy and its constituents, such as genistein, have been consumed at high levels in several Asian populations without apparent adverse effects, concern has been raised about potential adverse effects due to estrogenic and other activities. The subchronic and chronic safety of genistein were evaluated in the beagle dog including a 4-week study and a 52-week safety study with a 13 week interim sacrifice and a 4 week recovery period. In both studies at doses of 50, 150 and 500 mg/kg/day, genistein was well tolerated. In the 4 week study, except for an increase in uterine weights in female dogs at 500 mg/kg/day, there were no other treatment related findings. In the 52-week study, the primary effects of genistein were observed on the reproductive tract, which included for male dogs: reduced size and/or weight of the testes, epididymus and prostate of 2/2 dogs after 13 weeks of treatment and in 1/4 dogs after 52 weeks of treatment at 500 mg/kg/day. The histological changes observed in the affected dogs at 500 mg/kg/day indicated atrophy of the testes and prostate gland and absent spermatozoa in the epididymus. At the mid-dose of 150 mg/kg/day, although there was a reduction to a lesser extent in testes weight after 13, but not 52 weeks, there were no histopathological changes. In female dogs, the reproductive tract effects included increased uterine weight at 500 mg/kg/day after 13 weeks of treatment, but not after 52 weeks of treatment. There was also a small decrease in ovarian weights at 150 and 500 mg/kg/day after 13 weeks and at 500 mg/kg/day after 52 weeks of treatment. There were no histopathological correlates to the changes in organ weights in female dogs. In the 4-week recovery group dogs, no changes were observed in dogs previously treated for 52 weeks with 500 mg/kg/day of genistein. It is concluded that the administration of genistein to dogs for a period of 4-52 weeks was well tolerated and did not result in systemic toxicity. Effects of genistein on the reproductive tract at very high doses were functional in nature and are of a type that would be expected in view of the relatively weak estrogenic activity of genistein and were considered not adverse effects. In the 4-week study, the no observed adverse effect level (NOAEL) for genistein was considered to be >500 mg/kg/day and the no observed effect level (NOEL) was considered to be 150 mg/kg/day. For the 52-week study, the NOAEL is considered to be >500 mg/kg/day and the NOEL is considered to be 50 mg/kg/day.

Effect of storage temperature and water activity on the content and profile of isoflavones, antioxidant activity, and in vitro protein digestibility of soy protein isolates and defatted soy flours

The aim of this work was to study the effect of 1 year of storage at different temperatures and 1 month of storage at different water activities on the content and profile of isoflavones, antioxidant activity, and in vitro protein digestibility of defatted soy flours (DSF) and soy protein isolates (SPI). The storage for up to 1 year, at temperatures from -18 to 42 degrees C, had no effect on the total content of isoflavones, but the profile changed drastically at 42 degrees C, with a significant decrease of the percentage of malonylglucosides with a proportional increase of beta-glucosides. A similar effect was observed for SPI stored at a(w) = 0.87 for 1 month. For DSF, however, there was observed a great increase in aglycons (from 10 to 79%), probably due to the action of endogenous beta-glucosidases. The antioxidant activity decreased after storage at 42 degrees C, but the in vitro protein digestibility did not change.

Genistein reverses changes of the proteome induced by oxidized-LDL in EA.hy 926 human endothelial cells

Endothelial cells are primary targets for pro-atherosclerotic stressors such as oxidized LDL (ox-LDL). The isoflavone genistein, on the other hand, is suggested to prevent a variety of processes underlying atherosclerosis and cardiovascular diseases. By analyzing the proteome of EA.hy 926 endothelial cells, here we show, that genistein reverses the ox-LDL-induced changes of the steady-state levels of several proteins involved in atherosclerosis. These alterations caused by genistein are functionally linked to the inhibition of ox-LDL induced apoptosis.

Dietary daidzein influences laying performance of ducks (Anas platyrhynchos) and early post-hatch growth of their hatchlings by modulating gene expression

Our previous studies demonstrated that dietary supplementation of daidzein improves egg production in duck breeders during late periods of the laying cycle. The present study was aimed to clarify whether the growth of ducklings hatched from eggs laid by daidzein-treated hens would be affected, and to elucidate the mechanisms underlying potential trans-generational effects, by determining changes of hormone levels and mRNA expression of relevant genes. Daidzein was added to the basal diet of 415-day-old duck breeders at the level of 5 mg/kg. During 9 weeks of daidzein treatment, laying rate increased by 7.70%, average egg mass tended to increase, whereas yolk/albumen ratio decreased significantly. These changes were accompanied by significantly elevated plasma T4 and E2 levels, enhanced gonadotropin releasing hormone (GnRH) mRNA, but diminished estrogen receptor (ER)-beta mRNA expression in hypothalamus of daidzein-treated hens. Ducklings hatched from daidzein-treated eggs were significantly smaller at hatching, but they caught up with their control counterparts by 4 weeks of age. Serum levels of T4, pituitary GH, hepatic GH receptor (GHR) and type-1 IGF receptor (IGF-1R) mRNA expression were all suppressed markedly in the daidzein-treated group at hatching, but this suppression proved to be temporary, as at 4 weeks of age, expression levels of all investigated genes were restored. However, it is noteworthy that at 4 weeks of age an obvious down-regulation of hypothalamic GnRH mRNA expression was detected in ducklings maternally exposed to daidzein. Our results provide evidence that maternal exposure to daidzein affects post-hatch growth in the duck with accompanying changes in the secretion of metabolic hormones and expression of growth-related genes. Although the negative effect of maternal daidzein on embryonic growth could be eliminated 4 weeks after hatching, the long-term effect of maternal daidzein on reproductive function is not to be ignored and awaits further investigation.

Beta-glycosidase activity toward different glycosidic forms of isoflavones

Isoflavones, a group of soybean components that significantly contribute to human health and disease prevention, exist in various chemical forms. The enzyme activity can be very sensitive to molecular structure; thus, the profile of the isoflavones can affect their rate of hydrolysis. The objective of this work was to study the beta-glycosidase activities toward isoflavone beta-glycosides and their conjugated forms. Hydrolysis experiments were conducted where beta-glycosides and their conjugates were treated with beta-glycosidase. Results confirmed that beta-glycosidase can hydrolyze nonconjugated beta-glycosides into aglycones. However, when the enzyme amount and/or activity were limited, significant differences in enzyme activity toward the beta-glycosides were observed. On the other hand, beta-glycosidase was not effective in hydrolyzing the conjugated glycosides to their respective aglycones, even with increased levels of the enzyme and with prolonged incubation. The transformation of conjugated glycosides into their respective beta-glycosides will most likely result in increased hydrolysis rates and better absorption.

Antioxidant activities of black and yellow soybeans against low density lipoprotein oxidation

Several studies have demonstrated that the daily intakes of soy foods were associated with a reduced cardiovascular risk. The aim of our study was to investigate the inhibitory effect of black soybeans on low density lipoprotein (LDL) oxidation in comparison to yellow soybeans. The extract from black soybean had a longer LDL oxidation lag time than that from yellow soybean (205 +/- 16 and 65 +/- 3 min, respectively). When both soybeans were divided into the seed coat and the mixture of the germ and cotyledon, the diluted extract solution from the black soybean seed coat prolonged the lag time significantly more than the original extract of the yellow soybean seed coat. On the other hand, antioxidant effects of the extract from the mixture of germs and cotyledons were similar in both soybeans. Regarding total polyphenol contents, the seed coat of black soybean had a higher polyphenol content than that of yellow soybean (29.0 +/- 0.56 and 0.45 +/- 0.02 mg/g, respectively). Interestingly, the mixture of the germ and cotyledon hydrolyzed by beta-glucosidase in both soybeans showed a stronger inhibitory effect on LDL oxidation than that before being hydrolyzed by beta-glucosidase. These results suggest that black soybeans may be more effective in inhibiting LDL oxidation than yellow soybeans because of total polyphenols contents in its seed coat. In addition, aglycones, which are rich in soybeans fermented or hydrolyzed by beta-glucosidase, may play a crucial role in the prevention of oxidation-related diseases.

Chemical compositions and physicochemical properties of the fiber-rich materials prepared from shoyu mash residue

Fiber-rich materials including desalted shoyu mash residue (briefly referred as desalted mash residue, DMR), alcohol-insoluble solid (AIS), and water-insoluble solid (WIS) were prepared from shoyu mash residue, which is a filtration cake obtained during the isolation of shoyu by press filtration of fermented matrix in the final process. The DMR, AIS, and WIS contain rich dietary fiber of 52.4, 61.5, and 54.7 wt %, respectively. The DMR, AIS, and WIS all have significantly lower bulk densities, and higher water-holding capacities, oil-holding capacities, swelling abilities, and cation-exchange capacities than the control cellulose. These results indicated that the said fiber-rich materials prepared in this study all have the desired physicochemical properties for being used as satisfactory sources of dietary fibers or low-calorie bulk ingredients in food applications requiring oil and moisture retention. Furthermore, the said fiber-rich materials also have high contents of isoflavones, mainly daidzein and genistein, which are considered as the most bioavailable phytoestrogens, with a total amount of about 1200-1480 micromol/100 g (equal to daidzein of ca. 3040-3759 microg/g, or genistein of 3240-3996 microg/g). The results revealed that the said fiber-rich materials might be a potent fiber source for health foods.

Isoflavones and postmenopausal women: a critical review

Isoflavonic phytoestrogens, or isoflavones, constitute a class of phytoestrogens that have properties similar to selective estrogen receptor modulators, and have attracted a substantial degree of attention in recent years, particularly as a possible alternative to the conventional hormone replacement therapy regimens used by postmenopausal women. Despite great promise, it is difficult to make many specific recommendations about their use at the current time, in light of the many outstanding questions that hopefully will be answered in the future by focused interventional studies involving humans. Studies to date indicate that the use of isoflavones to address vasomotor symptoms provides at most small benefits beyond a placebo effect, and no benefit for genital atrophy. As for postmenopausal women whose primary concern is cardiovascular disease, the recommendation of the American Heart Association to include soy protein foods as part of an otherwise healthy diet is well justified, and similarly the substitution of supplements containing soy protein for animal protein can also be recommended. The use of purified isoflavone supplements not containing soy protein may have some cardiovascular benefits, but these appear to be less substantial in degree than those provided by soy protein with isoflavones. In particular, more research is needed to assess the effects of isoflavones on osteoporosis, for which no recommendation regarding isoflavones can be made based on the current data. Also, isoflavones should not be taken by postmenopausal women for the specific purpose of decreasing their risk of breast or endometrial cancer, although, at least for those without pre-existing disease or at high risk, it seems quite unlikely that isoflavone use is harmful in this regard.

Effects of solvent polarity and acidity on the extraction efficiency of isoflavones from soybeans (Glycine max)

Soy isoflavones have been correlated with beneficial health effects. The predominant chemical forms of isoflavones present may affect their biological activities. Choosing the solvent system that can accurately quantify the amounts of individual isoflavones present in these products is paramount. Our objectives were to compare frequently used solvent systems and to evaluate the effects of polarity and acidity on the recovery of isoflavones from soybeans. Isoflavones were extracted from pulverized Manokin soybeans using six solvent systems, which are the combinations of three polarity levels (83% acetonitrile, 80% methanol, and 58% acetonitrile) and two acidity levels (nonacidified and acidified). The pulverized soybean was stirred for 2 h in each solvent system before filtration and concentration using rotary evaporation. The extract was resuspended in 16% acetonitrile and analyzed by high-performance liquid chromatography. Recoveries of pure standards were evaluated with all solvent systems. Solvents with a higher polarity extracted a significantly higher amount of total isoflavones. For individual isoflavones, 58% acetonitrile (highest polarity) extracted either the highest amounts or no less than other solvents, while 83% acetonitrile (lowest polarity) extracted either the lowest amounts or no more than other solvents except for the aglycone form. Acidification significantly reduced the recovery of the malonylglucoside form and the total isoflavones. The recovery study revealed that acidification favored the chemical transformations of isoflavones during the extraction. Among the six solvent systems examined, 58% acetonitrile aqueous solution without acid was the best for extraction of isoflavones from soybeans.

Phytoestrogens derived from red clover: an alternative to estrogen replacement therapy?

The benefits of plant extracts from soy and red clover as alternatives to conventional hormone replacement therapy (HRT) have been debated in the past. Here, an attempt has been made to summarize the biochemical and pharmacological data in the light of clinical aspects. Red clover and soy extracts contain isoflavones, which have a high affinity to estrogen receptor alpha (ERalpha), estrogen receptor beta (ERbeta), progesterone receptor (PR) and androgen receptor (AR). The higher affinity to ERbeta compared to ERalpha has been used as an explanation why red clover extracts function as food additives to treat menopausal disorders and may reduce risk of breast cancer. Biochemical analysis shows that these representatives of phytoestrogens have multiple actions beside selective estrogen receptor modulator (SERM)-activity. They act as selective estrogen enzyme modulators (SEEMs), have antioxidant activity and interact with transcription factors such as NF-kappaB. Furthermore, it is indicated that they have protective effects on osteoporosis and the cardiovascular system. Currently 40-50mg of isoflavones (biochanin A, daidzein, formononetin and genistein) are recommended as daily dose. This recommendation is based on the daily intake of phytoestrogens in a traditional Japanese diet.

Comparison of regulative functions between dietary soy isoflavones aglycone and glucoside on lipid metabolism in rats fed cholesterol

The effects of dietary soy isoflavones aglycone and glucoside on lipid metabolism were compared in male Sprague-Dawley rats (4 weeks old) given purified diets containing 0.3% cholesterol. The rats were fed a diet supplemented with either isoflavone aglycone-rich powder (IF-A group) or isoflavone glucoside-rich powder (IF-G group) or isoflavone-free diet (control group) for 40 days. The additional level of isoflavone aglycone moiety in the diet was prepared to the same level (approximately 0.096 g/100 g: approximately 0.1% in diet). The activity of hepatic cholesterol 7alpha-hydroxylase tended to be slightly higher in the rats fed isoflavones than in those fed the isoflavone-free diet. On the other hand, the activity of hepatic Delta6 desaturase in the IF-A group was lower than that of the control group. Reflecting this effect, the Delta6 desaturation indices [(20:3n-6+20:4n-6)/18:2n-6] in liver phospholipids of the IF-A group were lower than those in the control group. Liver and serum total cholesterol levels and liver TG level were also reduced by consumption of isoflavone aglycone. Moreover, serum TG level was lowered by consumption of both isoflavones aglycone and glucoside. The level of serum total isoflavones in the IF-A group was significantly higher than that in the IF-G group. Therefore, we speculate that the absorption speed of isoflavone aglycones might be faster than that of isoflavone glucosides in rats. This study suggests that dietary soy isoflavones, particularly their aglycone form, may exert a beneficial effect on lipid metabolism in rats fed cholesterol.

Pharmacokinetics of a slow-release formulation of soybean isoflavones in healthy postmenopausal women

Pharmacokinetic studies of soybean isoflavones have shown that following oral ingestion, the two major isoflavones, daidzin and genistin, are hydrolyzed in the intestine, rapidly absorbed into the peripheral circulation, and eliminated from the body with a terminal half-life of 7-8 h. These characteristics make maintenance of steady-state plasma isoflavone concentrations difficult to attain unless there is repeated daily ingestion of foods or supplements containing isoflavones. In an attempt to sustain more constant plasma isoflavone concentrations, a new slow-release formulation of a soybean isoflavone extract was prepared by microencapsulation with a mixture of hydroxypropylcellulose and ethylcellulose to alter its dissolution characteristics. In vitro experiments confirmed slow aqueous dissolution of isoflavones from this formulation when compared with the conventional isoflavone extract. The pharmacokinetics of this slow-release isoflavone extract was studied in 10 healthy postmenopausal women after oral administration of a single capsule containing the equivalent of 22.3 mg of genistein and 7.47 mg of daidzein expressed as aglycons. A comparison of the key pharmacokinetic parameters obtained in this study with those established in extensive studies performed previously in this laboratory indicated that the mean residence time of genistein and daidzein increased 2-fold with microencapsulation. These findings are indicative of a decreased rate of absorption, consistent with the observed slow in vitro dissolution rate. These findings show that it is feasible to employ polymer matrices that slow the aqueous dissolution for preparing sustained-release formulations of soy isoflavones. Further studies to optimize such formulations are warranted.

Antioxidant properties of soybean isoflavone extract and tofu in vitro and in vivo

Isoflavones in soybean were extracted in the crude form using 80% food-grade ethanol at 80 degrees C for 6 h and followed by concentration and dehydration. The soy extract contained isoflavones primarily in the forms of glucosides. In vitro antioxidant activities of the soy extract containing 20-500 ppm isoflavones were conducted using a Rancimat method. The results showed that soy isoflavone extract had strong in vitro antioxidant activity. There was a dose-dependent response for the in vitro antioxidant activity at the lower concentrations but not at the higher concentrations. In vivo antioxidant property was determined by measuring the antioxidant enzymes, superoxide dismutase, and catalase in various organs of rats that were fed with diets containing partially oxidized oil and various levels of isoflavones for up to 24 weeks. Neither short-term (8 weeks) feeding nor low isoflavone content (50 ppm) induced changes in superoxide dismutase or catalase activities in rats. Only diets containing high isoflavone contents (150 and 250 ppm) showed obvious elevated enzymatic levels in various organs. In addition, a laboratory-prepared tofu containing approximately 50 ppm isoflavones had better effects than the soy extract with the 250 ppm isoflavone group, which indicated that molecules other than isoflavones may have a synergistic effect on in vivo antioxidant enzyme inductions of tofu.

Determinants for urinary and plasma isoflavones in humans after soy intake

Consumption of soy foods leads to a biphasic appearance pattern of isoflavones (IFLs) in blood and urine, with peaks appearing at 1-2 h and 4-8 h after intake, but its causes are not understood. IFLs were measured repeatedly from plasma and/or urine after intake of soy foods, IFL glucosides, or aglycons without or with a mildly or radically reduced gut flora as a result of oral antibiotic (AB) treatment, or this combined with mechanical bowel preparation (AB+MBP). The typical biphasic IFL pattern in blood and/or urine was observed when a soy protein drink without (control) or with AB treatment or when IFL glucosides or aglycons were consumed. Soy intake combined with AB+MBP or consumption of puerarin led to a shift of the second peak to much later times. The first peak was absent after puerarin intake. Total urinary IFL recovery was more than 50% lower in the first 24 h, but overall 61% higher after AB+MBP vs. the control. When the area under the curves for corresponding time intervals were compared, individual or total urinary IFL excretion rates were highly correlated with individual or total plasma IFL levels (r=0.85-0.91; P <0.001). At the same urinary excretion rate three times more genistein than daidzein remained in the circulation. We conclude that urinary IFL excretion rates reflect circulating IFL levels, with daidzein appearing less in blood and more in urine than genistein. The first and second IFL peaks are due to uptake in the small and large intestine, respectively. The latter is the major locus of uptake (90%) at usual dietary IFL doses (0.15-1.5 mmol/kg body weight). A reduced gut flora delayed IFL uptake but led overall to increased urinary recovery because of less bacterial degradation in the intestine.

Cellular uptake and efflux of trans-piceid and its aglycone trans-resveratrol on the apical membrane of human intestinal Caco-2 cells

Two stilbenes (trans-piceid and its aglycone trans-resveratrol) were investigated in the uptake across the apical membrane of the human intestinal cell line Caco-2 in order to determine their mechanisms of transport. The uptake was quantified using a reverse phase high-performance liquid chromatography method with fluorescence detection. The rate of cellular accumulation in the cells was found to be higher for trans-resveratrol than for trans-piceid. In addition, trans-resveratrol uses passive transport to cross the apical membrane of the cells, whereas the transport of trans-piceid is likely active. With regard to the mechanisms of transport, the involvement of the active transporter SGLT1 in the absorption of trans-piceid was deduced using various inhibitors directly or indirectly exploiting the activity of this transporter (glucose, phlorizin, and ouabain). Moreover, we investigated the involvement of the multidrug-related protein 2 (MRP2), an efflux pump present on the apical membrane, in stilbene efflux by Caco-2 cells. The effect of MK-571 (an MRP inhibitor) seems to implicate MRP2 as responsible for apical efflux of trans-piceid and trans-resveratrol.

Genistein affects androgen-responsive genes through both androgen- and estrogen-induced signaling pathways

This study examined the mechanisms by which the prostate cancer chemopreventive agent genistein modulates gene expression in LNCaP human prostate cancer cells. Expression of androgen- and estrogen-regulated genes was measured in LNCaP cells cultured in the presence or absence of hormonal stimulation and the presence or absence of genistein. Genistein strongly suppressed basal expression of androgen-responsive gene (ARG) mRNAs, including prostate-specific antigen (PSA) and Ste20-related proline-alanine-rich kinase (SPAK). However, genistein had little or no effect on basal expression of two other ARGs, beta2-microglobulin (B2M) or selenoprotein P (SEPP1). Culturing LNCaP cells in the presence of the synthetic androgen R1881-induced increases in PSA, SPAK, B2M, and SEPP1 mRNA levels. The R1881-induced expression of these genes was uniformly blocked by genistein. For PSA and SPAK, genistein also blocked or downregulated 17beta-estradiol-induced increases in mRNA expression. These results indicate that genistein selectively alters expression of ARG mRNAs in LNCaP cells through modulation of both androgen- and estrogen-induced signaling pathways.

Bioavailability and bioefficacy of polyphenols in humans. II. Review of 93 intervention studies

For some classes of dietary polyphenols, there are now sufficient intervention studies to indicate the type and magnitude of effects among humans in vivo, on the basis of short-term changes in biomarkers. Isoflavones (genistein and daidzein, found in soy) have significant effects on bone health among postmenopausal women, together with some weak hormonal effects. Monomeric catechins (found at especially high concentrations in tea) have effects on plasma antioxidant biomarkers and energy metabolism. Procyanidins (oligomeric catechins found at high concentrations in red wine, grapes, cocoa, cranberries, apples, and some supplements such as Pycnogenol) have pronounced effects on the vascular system, including but not limited to plasma antioxidant activity. Quercetin (the main representative of the flavonol class, found at high concentrations in onions, apples, red wine, broccoli, tea, and Ginkgo biloba) influences some carcinogenesis markers and has small effects on plasma antioxidant biomarkers in vivo, although some studies failed to find this effect. Compared with the effects of polyphenols in vitro, the effects in vivo, although significant, are more limited. The reasons for this are 1) lack of validated in vivo biomarkers, especially in the area of carcinogenesis; 2) lack of long-term studies; and 3) lack of understanding or consideration of bioavailability in the in vitro studies, which are subsequently used for the design of in vivo experiments. It is time to rethink the design of in vitro and in vivo studies, so that these issues are carefully considered. The length of human intervention studies should be increased, to more closely reflect the long-term dietary consumption of polyphenols.

Inhibition of carcinogenesis by polyphenols: evidence from laboratory investigations

Many plant polyphenolic compounds have been shown to have cancer-preventing activities in laboratory studies. For example, tea and tea preparations have been shown to inhibit tumorigenesis in a variety of animal models of carcinogenesis, involving organ sites such as the skin, lungs, oral cavity, esophagus, stomach, liver, pancreas, small intestine, colon, and prostate. In some of these models, inhibitory activity was demonstrated when tea was administered during the initiation, promotion, or progression stage of carcinogenesis. The cancer-preventing activities of these and other polyphenols, such as curcumin, genistein, and quercetin, are reviewed. In studies in vitro, many of these compounds have been shown to affect signal transduction pathways, leading to inhibition of cell growth and transformation, enhanced apoptosis, reduced invasive behavior, and slowed angiogenesis. However, the concentrations used in cell culture studies were much higher than those found in vivo. If we propose mechanisms for cancer prevention on the basis of cell line experiments, then these activities must be demonstrated in vivo. The bioavailability, ie, tissue and cellular concentrations, of dietary polyphenols is a determining factor in their cancer-preventing activity in vivo. For example, compounds such as curcumin are effective when applied topically to the skin or administered orally to affect the colon but are not effective in internal organs such as the lungs. More in-depth studies on bioavailability should facilitate correlation of mechanisms determined in vitro with in vivo situations, increase our understanding of dose-response relationships, and facilitate extrapolation of results from animal studies to human situations.

Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies

Polyphenols are abundant micronutrients in our diet, and evidence for their role in the prevention of degenerative diseases is emerging. Bioavailability differs greatly from one polyphenol to another, so that the most abundant polyphenols in our diet are not necessarily those leading to the highest concentrations of active metabolites in target tissues. Mean values for the maximal plasma concentration, the time to reach the maximal plasma concentration, the area under the plasma concentration-time curve, the elimination half-life, and the relative urinary excretion were calculated for 18 major polyphenols. We used data from 97 studies that investigated the kinetics and extent of polyphenol absorption among adults, after ingestion of a single dose of polyphenol provided as pure compound, plant extract, or whole food/beverage. The metabolites present in blood, resulting from digestive and hepatic activity, usually differ from the native compounds. The nature of the known metabolites is described when data are available. The plasma concentrations of total metabolites ranged from 0 to 4 mumol/L with an intake of 50 mg aglycone equivalents, and the relative urinary excretion ranged from 0.3% to 43% of the ingested dose, depending on the polyphenol. Gallic acid and isoflavones are the most well-absorbed polyphenols, followed by catechins, flavanones, and quercetin glucosides, but with different kinetics. The least well-absorbed polyphenols are the proanthocyanidins, the galloylated tea catechins, and the anthocyanins. Data are still too limited for assessment of hydroxycinnamic acids and other polyphenols. These data may be useful for the design and interpretation of intervention studies investigating the health effects of polyphenols.

Lactobacillus gasseri: effects on mouse intestinal flora enzyme activity and isoflavonoids in the caecum and plasma

The effects of Lactobacillus gasseri JCM 1131(T) on isoflavonoid levels within the caecum and plasma were assessed in adult mice. Male 5-week-old mice were fed an AIN 93M diet for 30 d. Two groups of mice were administered either L. gasseri JCM 1131(T) (the LGI group) or physiological saline solution (the control (CI) group) daily for 5 d before dissection. The plasma daidzein concentration was significantly higher in the LGI group, however, their plasma equol concentration was significantly less than in the CI group. The total amount of equol present as aglycone in the caecum was significantly greater in the CI group, but there was no significant difference in the total daidzein present as caecal aglycone. In an in vitro incubation of daidzein with the faecal flora of mice, the equol concentration was significantly higher in the CI group. The numbers of lactobacilli present were significantly higher in the LGI group. The present data suggest that the administration of L. gasseri is likely to influence the effect of isoflavonoids on the host via changes in the gastrointestinal environment.

Using DNA microarray analyses to elucidate the effects of genistein in androgen-responsive prostate cancer cells: identification of novel targets

Many studies have correlated the consumption of soy-rich diets with a decreased risk of developing hormone-dependent cancers, including prostate cancer. Genistein is a candidate prostate cancer preventive phytochemical found at high levels in soybean and soy foods. To better understand the molecular mechanisms underlying the beneficial effects of genistein on prostate cancer prevention, we used a DNA microarray approach to examine the effects of genistein at concentrations in the physiologic range on global gene expression patterns in androgen-responsive cancer cells. Microarray analyses were performed on androgen-responsive LNCaP human prostate cancer cells exposed to 0, 1, 5, or 25 microM genistein. We found a concentration-dependent modulation of multiple cellular pathways that are important in prostate carcinogenesis. Interestingly, the androgen receptor (AR)-mediated pathways, in particular, appeared to be modulated by genistein at the lowest concentrations. Based on these results, we propose that the regulation of AR-mediated pathways is potentially the most relevant chemopreventive mechanism for genistein administered at physiologic levels.

Effect of genistein supplementation on tissue genistein and lipid peroxidation of serum, liver and low-density lipoprotein in hamsters

The aim of this study was to investigate the effects of genistein supplementation in a vitamin E-deficient diet on the genistein concentrations and the lipid oxidation of serum, liver and low-density lipoprotein (LDL) of hamsters. Thirty-six male hamsters were randomly divided into three groups and fed a vitamin E-deficient semisynthetic diet (AIN-76) containing different levels of genistein, i.e., G0 (control group, genistein-free diet), G50 (50 mg genistein/kg diet) and G200 (200 mg genistein/kg diet) for 5 weeks. The concentrations of genistein in serum and liver significantly increased with the increase of genistein supplementation. The vitamin E contents in LDL were higher in hamsters fed G50 or G200 diets than in hamsters fed genistein-free diet. Genistein supplementation to hamsters significantly reduced the propagation rate during conjugated diene formation of LDL oxidation, and the lag time of LDL oxidation in hamsters fed G200 diets was significantly lower than that of G0 diets. In addition, genistein supplementation significantly raised serum total antioxidant capacity and decreased the thiobarbituric acid-reactive substances (TBARS) of LDL and liver in hamsters. However, no significant differences in TBARS were found in serum, irrespective of genistein addition. On the other hand, the relative contents of polyunsaturated fatty acids in LDL were decreased after genistein supplementation. There was a negative correlation between lag time and P/S ratio, and a positive correlation between lag time and vitamin E contents. These data demonstrate that genistein supplementation markedly increased its concentrations in body tissues and reduced oxidative stress of lipid oxidation of serum, liver and LDL.

The apparent absorptions of isoflavone glucosides and aglucons are similar in women and are increased by rapid gut transit time and low fecal isoflavone degradation

We hypothesized that there would be no difference in apparent absorption, as assessed by urinary excretion, between isoflavone sources rich in glucosides or aglucons and that subjects with rapid gut transit time (GTT) and low fecal isoflavone degradation phenotype would absorb more isoflavones. Women (n = 13) with a fecal daidzein degradation rate constant, D(k) > 0.30 h(-1) (high degraders) and GTT of 106 +/- 11 h and women (n = 12) with D(k) < 0.20 h(-1) (low degraders) and GTT of 71 +/- 12 h were randomly assigned to 3 treatments: soygerm (1.1 micromol/kg body weight, n = 5 high degraders, 4 low degraders), fermented soygerm (3.3 micromol/kg, n = 4 high and 4 low degraders) or Novasoy isoflavone extract (1.5 micromol/kg, n = 4 high and 4 low degraders) for 7 d. By HPLC analysis, 24-h urinary excretion of soygerm was greater than Novasoy (51 +/- 6 vs. 26 +/- 6% of ingested dose, P < 0.05). Women of the low daidzein degradation phenotype had greater urinary isoflavone excretion than did women of the high daidzein degradation phenotype (51.6 +/- 4.8 vs. 33.8 +/- 4.7%, P < 0.05, mean of d1 and 7). The plasma total isoflavone level (estimated as a percentage of the ingested amount, mean of d 1 and 7) differed between women who consumed fermented soygerm and soygerm 3 h after feeding (1.8 +/- 0.3 vs. 0.5 +/- 0.3%, P < 0.05). Urinary excretions of aglucons and glucosides did not differ. The study confirmed that rapid GTT and low fecal isoflavone degradation rate increased the apparent absorption of isoflavones.

Biotransformation of soy isoflavone-glycosides in laying hens: intestinal absorption and preferential accumulation into egg yolk of equol, a more estrogenic metabolite of daidzein

Dietary soy-isoflavones have recently been noted as phytoestrogens with potentially beneficial effects on human health, and they are biologically transformed in the intestinal tract into aglycones and further into several specific metabolites. Here we report that in laying hens daidzin, a soy isoflavone-glycoside, in the diet was transformed into equol, absorbed, transported in circulating peripheral blood, and preferentially accumulated into egg yolk in its conjugated form. Laying hens were fed experimental diets containing two levels of soy isoflavone-glycosides (177 or 528 mg per 100 g diet) for 21 or 42 days, and blood and eggs were collected at 1- to 9-day intervals. HPLC analyses revealed that most of the isoflavones (daidzein, glycitein, and genistein) and a metabolite, equol, were present in blood and egg yolk in conjugated form. The concentration of equol-conjugates in blood plasma and egg yolk was higher than any of the other three isoflavone-conjugates analyzed and, especially in egg yolk, the equol-conjugates comprised no less than 60% of the total isoflavone-conjugates. The isoflavones, including equol, distributed mostly (95%) in the high-density fraction of blood serum, and more (65%) in the granule fraction of egg yolk. These results raise the possibility that feeding domestic animals soy-based fodder produces animal-based foods rich in a more active form of phytoestrogens.

Identification of puerarin and its metabolites in rats by liquid chromatography-tandem mass spectrometry

Puerarin (daidzein-8-C-glucoside) is the major bioactive isoflavone of kudzu root (the root of Pueraria lobata). Its metabolic fate, however, is not well-known. In this study, a sensitive and specific LC-ESI-MS/MS method for the determination of puerarin and its metabolites daidzein, dihydrodaidzein, and equol was developed for their analysis in biological samples. Two new metabolites of puerarin, mono- and dihydroxylated derivatives, were detected in the urine and feces of rats after oral administration. The persistence of puerarin in blood and urine as the principal metabolic form for the period of 4-72 h after oral administration suggested that puerarin is rapidly absorbed from the intestine without metabolism. Its presence in organs such as the brain suggests that this glucoside may enter tissues by specific transport pathways. Study of these metabolites may provide further understanding of the health beneficial effects of puerarin in kudzu dietary supplements.

Radiation-induced enhancement of antioxidant contents of soybean (Glycine max Merrill)

Soybean samples were treated with gamma-radiation doses between 0.5 and 5 kGy for achieving insect disinfestation and microbial decontamination. Nutritional quality of soybeans with respect to antioxidant isoflavone content was tested in radiation-treated and untreated samples. Changes in major isoflavones such as genistein, diadzein, glycetein, and their glycosides were monitored by high-performance liquid chromatography. Interestingly, a decrease in content of glycosidic conjugates and an increase in aglycons were noted with increasing radiation dose. Antioxidant potential measured as percent 1,1-diphenyl-2-picrylhydrazyl scavenging activity showed an increasing trend with dose, indicating that radiation processing as a method of food preservation has a positive nutritional implication.

Polyphenols: food sources and bioavailability

Polyphenols are abundant micronutrients in our diet, and evidence for their role in the prevention of degenerative diseases such as cancer and cardiovascular diseases is emerging. The health effects of polyphenols depend on the amount consumed and on their bioavailability. In this article, the nature and contents of the various polyphenols present in food sources and the influence of agricultural practices and industrial processes are reviewed. Estimates of dietary intakes are given for each class of polyphenols. The bioavailability of polyphenols is also reviewed, with particular focus on intestinal absorption and the influence of chemical structure (eg, glycosylation, esterification, and polymerization), food matrix, and excretion back into the intestinal lumen. Information on the role of microflora in the catabolism of polyphenols and the production of some active metabolites is presented. Mechanisms of intestinal and hepatic conjugation (methylation, glucuronidation, sulfation), plasma transport, and elimination in bile and urine are also described. Pharmacokinetic data for the various polyphenols are compared. Studies on the identification of circulating metabolites, cellular uptake, intracellular metabolism with possible deconjugation, biological properties of the conjugated metabolites, and specific accumulation in some target tissues are discussed. Finally, bioavailability appears to differ greatly between the various polyphenols, and the most abundant polyphenols in our diet are not necessarily those that have the best bioavailability profile. A thorough knowledge of the bioavailability of the hundreds of dietary polyphenols will help us to identify those that are most likely to exert protective health effects.

Isoflavones found in Korean soybean paste as 3-hydroxy-3-methylglutaryl Coenzyme A reductase inhibitors

3-Hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase is the rate-limiting enzyme in the biosynthesis of cholesterol in mammals. Some microbial metabolites have been found to be HMG-CoA reductase inhibitors. Korean soybean paste is a unique food fermented by many microorganisms. The enzymatic method using the catalytic domain of Syrian hamster HMG-CoA reductase was employed for the screening of HMG-CoA reductase inhibitors. Soybean paste extract was fractionated by vacuum liquid chromatography. Fractions showing relatively high HMG-CoA reductase inhibition were further purified through Sephadex LH-20 column chromatography and C18 preparative HPLC, and the inhibitory compounds were identified as genistein, daidzein, and glycitein.

Effects of dose and glycosylation on the transfer of genistein into the eggs of the Japanese quail (Coturnix japonica)

Soy isoflavones have been associated with several beneficial effects of soy in human diets. However, most soy is consumed by livestock in the Western countries. It is possible that isoflavones could be transferred and/or accumulated into animal products, which could become additional sources of dietary isoflavones for humans. Our objectives were to determine whether dietary isoflavone genistein could be transferred and/or accumulated into the eggs of Japanese quail (Coturnix japonica) and how the supplementation dosage and glycosylation of the isoflavone would affect this transfer. Adult reproductive female Japanese quail were randomly assigned to treatment groups that received encapsulated 50 or 100 mg genistein or 80 mg genistin per day (four quail per treatment) for 5 days. A control group (two quail) received placebo capsules. Eggs were collected prior to treatment and then daily for 15 days. The egg, separated into yolk and white, and pulverized quail diet were extracted in 80% methanol for 2 h and either centrifuged or filtered before evaporation of the solvent. The extracts were redissolved in 16% acetonitrile for high-performance liquid chromatography (HPLC) analyses. Genistein and genistein metabolites were detected in the egg yolks of treated quail. Trace concentrations of genistein were detected in the control group, due to the presence of genistein derivatives in the diet. Neither genistein nor its metabolites were found in egg white. Levels of genistein in the eggs increased significantly from the 3rd day of supplementation and reached the maximum about 2 days after the supplementation stopped. The higher dose of genistein supplementation resulted in higher genistein concentrations in egg yolks. Glycosylation decreased the transfer and accumulation of genistein into the egg yolks.

Serum phytoestrogens and prostate cancer risk in a nested case-control study among Japanese men

The purpose of this study was to examine whether a high serum concentration of phytoestrogens reduces the risk of prostate cancer in a case-control study nested in a community-based cohort in Japan (Japan Collaborative Cohort (JACC) Study). Information on lifestyles and sera of the subjects were collected in 1988-90, and they were followed up to 1999. Incident and dead cases of prostate cancer and controls were matched for study area and age. Phytoestrogens and sex hormones in sera stored at - 80 degrees C were measured in 2002. Of 14,105 male subjects of the cohort who donated their sera, 52 cases and 151 controls were identified. Three datasets were analyzed; 1) all subjects, 2) 40 cases and 101 controls after excluding subjects with low testosterone levels who were suspected of having had medical intervention, and 3) 28 cases and 69 controls with prostate specific antigen level of Collapse

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MESH Headings

• Adult
• Biomarkers, Tumor/blood
• Case-Control Studies
• Humans
• Isoflavones/blood
• Japan
• Male
• Middle Aged
• Odds Ratio
• Phytoestrogens
• Plant Preparations/blood
• Prostatic Neoplasms/blood
• Risk Factors

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Affiliation(s)

Kotaro Ozasa Department of Epidemiology for Community Health and Medicine, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kamigyo-ku, Kyoto 602-8566, Japan.
Masahiro Nakao
Yoshiyuki Watanabe
Kyohei Hayashi
Tsuneharu Miki
Kazuya Mikami
Mitsuru Mori
Fumio Sakauchi
Masakazu Washio
Yoshinori Ito
Koji Suzuki
Kenji Wakai
Akiko Tamakoshi

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Determination of new derivatives of genistein in culture media by liquid chromatography

Methods for determination of genistein and its four new analogues in culture media have been developed to support studies on their potential anticancer activities. The investigated compounds were extracted from the media using liquid-liquid extraction with appropriate solvent. After evaporation of organic solvents each of the dry extracts was reconstituted in appropriate mobile phase. Reversed-phase HPLC was applied to quantitative determining of tested compounds. The methods are specific, sensitive and technically simple. They were used to evaluate concentration level of investigated compounds in experiments with human promyelocytic leukemia cells (HL-60 cell line).

Isoflavone profile and biological activity of soy bread

The present study examines the ability of isoflavone extracts from whole soy bread and two soy bread fractions, crumb and crust, to modulate the proliferation of human prostate cancer PC-3 cells. Total isoflavone content in the two fractions of soy bread were similar (3.17 micromol/g dry basis). However, their conjugate patterns were altered. Both fractions of soy bread contained a similar level of isoflavone aglycones ( approximately 24%). Low concentrations of soy bread extracts increased PC-3 cell proliferation as much as 47% compared to untreated control. This proliferative effect in cell growth was reduced at higher extract concentration. Soy bread crust extract (10 mg/mL) reduced PC-3 cell proliferation by 15% compared to untreated control. Interestingly, wheat bread extracts increased cell proliferation at all concentrations tested. Although extracts from both breads possessed biological activity, only soy bread crust extract reduced PC-3 cell proliferation. This observation may be related to the presence of soy in this bread.

Antioxidant isoflavones in Osage orange, Maclura pomifera (Raf.) Schneid

Recent findings that many human chronic diseases are associated with oxidative stresses have instigated the search for dietary antioxidants. Many phytochemicals, particularly phenolic compounds, have been found to possess strong antioxidant activity and reduce the risks of those diseases. Isoflavones, a special phenolic group found in soybean, have been found to act as antioxidants in some model systems. This study investigated the isoflavone content in a unique nonedible tree fruit, Osage orange [Maclura pomifera (Raf.) Schneid], and methods for the extraction, identification, and quantification of the two major isoflavones, osajin and pomiferin, were developed. The ethyl acetate extract contained 25.7% osajin and 36.2% pomiferin, and the two isoflavones were at 9.5 g kg(-1) of fresh Osage orange. Two model systems, FRAP and beta-CLAMS, were used to measure the antioxidant activity of these two isoflavones. Pomiferin was found to be a strong antioxidant in both systems, comparable to the antioxidant vitamins C and E and the synthetic antioxidant BHT. Osajin and the two soybean isoflavones (genistein and daidzein) showed no antioxidant activity. Although the Osage orange fruit is not a food source, it is considered to be safe and, therefore, a potentially good source of an antioxidant nutraceutical and functional food ingredient.