Soy isoflavones have an antiestrogenic effect and alter mammary promoter hypermethylation in healthy premenopausal women

We determined if soy isoflavones have dose-related estrogenic and methylation effects. Thirty-four healthy premenopausal women were randomized to 40 mg or 140 mg isoflavones daily through one menstrual cycle. Breast specific and systemic estrogenic effects were assessed measuring the estrogenic marker complement (C)3 and changes in cytology, whereas methylation assessment of 5 cancer related genes (p16, RASSF1A, RARbeta2, ER, and CCND2) was performed on intraductal specimens. Serum genistein significantly increased after consuming both isoflavone doses. Cytology did not significantly change at either isoflavone dose. Serum C3 levels posttreatment were inversely related to change in serum genistein (r =-0.76, P = 0.0045) in women consuming low but not high dose isoflavones. The RAR beta 2 hypermethylation increase posttreatment correlated with the posttreatment genistein level considering the entire group (r = 0.67, P = 0.0017) and those receiving high-dose isoflavones (r = 0.68, P = 0.021). At the low but not the high isoflavone dose, CCND2 hypermethylation increase correlated with posttreatment genistein levels (r = 0.79, P = 0.011). In summary, the inverse correlation between C3 and genistein suggests an antiestrogenic effect. Isoflavones induced dose-specific changes in RARbeta2 and CCND2 gene methylation, which correlated with genistein levels. This work provides novel insights into estrogenic and methylation effects of dietary isoflavones.

Concentrations of isoflavones and their metabolites in the blood of pregnant and non-pregnant heifers fed soy bean

The present study compared the changes in isoflavones (daidzein and genistein) and their metabolite (equol and para-ethyl-phenol) concentrations in the blood plasma of cyclic and pregnant heifers after feeding with soy bean. Twelve healthy heifers were divided into three groups: cyclic heifers (days 8-12 of the estrous cycle; control group; n=4), an early pregnancy group (2 months pregnant; n=4) and a late pregnancy group (8 months pregnant; n=4). All heifers were fed a single dose of 2.5 kg of soy bean and then blood samples were taken from the jugular vein for 8 h at predetermined intervals. The concentrations of soy bean-derived isoflavones and their active metabolites were measured in the blood plasma on an HPLC system. In the blood plasma of the early- and late-pregnant heifers, we found lower concentrations and time-dependent decreases in daidzein and genistein in comparison to cyclic heifers (P<0.05). Moreover, we noticed significant increases of equol and para-ethyl-phenol in the blood plasma of the early-pregnant heifers (P<0.05). In contrast, in the blood plasma of the late-pregnant heifers, we did not find an increase in the isoflavone metabolite concentrations compared with the early-pregnant heifers (P>0.05). In conclusion, physiological status (cyclicity or pregnancy) of the females influenced the concentrations of isoflavone metabolites in the blood plasma of the heifers. The stage of pregnancy affects isoflavone absorption, biotransformation and metabolism differently and results in higher concentrations of active metabolites of isoflavones during early pregnancy in comparison to their lower concentrations during late pregnancy. Therefore, we surmise that cows are more sensitive to active isoflavone metabolite actions during early pregnancy than cyclic heifers and heifers in late pregnancy.

Self-Microemulsifying Drug Delivery Systems (SMEDDS) for Improving In Vitro Dissolution and Oral Absorption of Pueraria Lobata Isoflavone

The aim of our investigation was to develop and characterize self-microemulsifying drug delivery systems (SMEDDS) of Pueraria lobata isoflavone to improve its in vitro dissolution and oral absorption in beagle dogs. SMEDDS consisted of oil (ethyl oleate), a surfactant (Tween 80), and a cosurfactant (Transcutol P). In all the SMEDDS, the level of Pueraria lobata isoflavone was fixed at 20% w/w of the vehicle. The in vitro self-microemulsification properties and droplet size analysis of SMEDDS were studied following their addition to water under mild agitation. A pseudoternary phase diagram was constructed identifying the efficient self-microemulsification region. From these investigations, an optimized formulation was selected and its dissolution and bioavailability were compared with a tablet formulation in beagle dogs. The in vitro dissolution rate of puerarin from SMEDDS was more than threefold faster than that from Yufengningxin tablets (Pueraria lobata isoflavone tablets). A 2.5-fold increase in the relative bioavailability was observed for the SMEDDS compared with Yufengningxin tablets. The absolute bioavailability of the SMEDDS was 82.32 +/- 15.51%, which was significantly improved compared with that of Yufengningxin tablets. These results demonstrate the potential of SMEDDS as an efficient way of improving the oral absorption of Pueraria lobata isoflavone.

Pharmacokinetic, Tissue Distribution, and Excretion of Puerarin and Puerarin-Phospholipid Complex in Rats

Puerarin is a potential therapeutic agent for cardiovascular diseases. But its poor oral bioavailability restricts its clinical application. In present study, as an evaluation of a formulation to improve the bioavailability of the drug, puerarin and its phospholipid complex were given to rats by intragastrically (i.g.) administration to compare pharmacokinetic, tissue distribution, and excretion. Serum samples were obtained at designated times after a single oral dose of 400 mg/kg puerarin or its complex. Tissue samples (heart, liver, spleen, kidney, lung, and brain), urine, and feces were collected and analyzed by a sensitive and specific high performance liquid chromatography (HPLC) method after i.g. administration of puerarin or its phospholipid complex. Compartmental and non-compartmental analyses were applied to the serum concentration versus time data. Pharmacokinetic parameters were calculated using the 3P97 pharmacokinetic software package. An open two-compartment, first-order model was selected for pharmacokinetic modeling. The results showed that after i.g. administration of 400 mg/kg puerarin and its phospholipid complex (equivalent to 400 mg/kg of puerarin), the pharmacokinetic parameters of the two formulations were different. The serum concentrations reached peaks at 0.894+/-0.521 h and 0.435+/-0.261 h, respectively, indicating the complex was more readily absorbed in serum than puerarin. The maximum concentrations for puerarin and its complex were 1.367+/-0.586 mg.L(-1) and 2.202+/-1.28 mg.L(-1) and AUC were 5.779+/-1.662 mg.h. L(-1) and 8.456+/-0.44 mg.h L(-1), respectively, indicating a higher bioavailability for the complex. The widely distribution characteristics of puerarin and its complex in tissues post-i.g. administration was identical and in a descending order as follows: lung, kidney, liver, heart, spleen, and brain. However, the amount was different. Puerarin distribution was higher in heart, lung, and brain after administering the complex. The cumulative 72 h urinary excretion of puerarin after i.g. administration of puerarin and its complex accounted for 1.05%, 1.11% of the administered dose, respectively. The cumulative feces excretion of puerarin was 32.3% and 25.5%. To sum up, oral administration of puerarin phospholipid complex modified the pharmacokinetics and tissue distribution of puerarin and it could be an effective oral formulation for puerarin.

Synthesis of haptens and conjugates for ELISA of glycitein: development and validation of an immunological test

Two carboxylic acid haptens of glycitein were synthesized, with a spacer arm at the C2 position. They differed in the length of the spacer arm, with the length of the spacer arms being three or four carbon atoms, and were named Delta3-glycitein and Delta4-glycitein haptens, respectively. The different haptens were coupled to bovine serum albumin (BSA), and the coupling efficiency was assessed by MALDI mass spectrometry. Polyclonal antibodies were generated against the BSA conjugates. An additional conjugate of Delta4-glycitein hapten was generated with swine thyroglobulin (Thyr). Enzyme-linked immunosorbent assays (ELISAs) based on the competition between free glycitein and Delta4-glycitein-Thyr conjugates for specific antibodies were developed. The IC50 of the standard curves was 15.6 ng mL(-1) with anti-Delta3-glycitein and 62.5 ng mL(-1) with anti-Delta4-glycitein, that is, 10.9 and 44 pmol/well, respectively. With the Delta3-glycitein antibody, interassay and intra-assay variations were 12.2 and 11.5%, respectively. Specificity tests did not show any significant cross-reaction with any other soy isoflavone. This specificity is not influenced by the length of the spacer arm. The assay was validated by measurements performed on plasma samples as well as on soy-based foodstuffs and on soy-based food supplements.

Plasma profiling of intact isoflavone metabolites by high-performance liquid chromatography and mass spectrometric identification of flavone glycosides daidzin and genistin in human plasma after administration of kinako

The roles of isoflavones in the prevention of several hormone-dependent cancers and osteoporosis are of great interest. Despite many pharmacokinetics studies of the isoflavones, the actual types of conjugates circulating in the body and the position(s) of conjugation sites on the flavone skeleton are still uncertain because, in general, conjugated compounds in biological fluids have been evaluated by measuring the free aglycones obtained after selective enzymatic hydrolysis. Using an high-performance (HPLC)-UV-diode-array detector (DAD) method combined with solid-phase extraction, we have obtained HPLC profiles of isoflavone glycosides [daidzin (Din) and genistin (Gin)] and of intact isoflavone metabolites in human plasma: daidzein, genistein, daizein-7-glucuronide, daidzein-4'-glucuronide, genistein-7-glucuronide, genistein-4'-glucuronide, daidzein-7-sulfate, daidzein-4'-sulfate, genistein-7-sulfate, and genistein-4'-sulfate. We investigated the plasma profile of intact isoflavone metabolites in plasma obtained 1 to-7 h after orally administration of 50 g of kinako (baked soybean powder) to two healthy volunteers. The results of DAD analysis indicated that the main isoflavone metabolite peaks were identified on the HPLC chromatogram. Furthermore, the intact glycosides Din and Gin were detected in 1-h plasma samples by their positive electrospray ionization mass spectra, demonstrating that the glycosides Din and Gin can be absorbed from the gut.

[Effect of verapamil on pharmacokinetics of puerarin in rats]

OBJECTIVE

To investigate the effect of verapamil on the pharmacokinetics of puerarin in rats.

METHOD

Puerarin with or without verapamil was administered intravenously or orally to rats. The concentration of puerarin in serum was determined by HPLC.

RESULT

No significant difference was found between the control and 0.5 microg x g(-1) verapamil combined groups for intravenous administration, and there was significant difference between the control and 2. 5 microg x g(-1) verapamil combined groups (P < 0.05). When puerarin was administered orally with verapamil, significant difference was found between the control and combined groups (P < 0.05).

CONCLUSION

Verapamil inhibited puerarin metabolism when puerarin was coadministered with verapamil, so it is necessary to change the therapeutic dose of puerarin.

Short-term effect of soy consumption on thyroid hormone levels and correlation with phytoestrogen level in healthy subjects

OBJECTIVE

Since soy isoflavones may influence the thyroid hormone feedback system by interference with their biosynthesis, secretion and metabolism, we tested whether their controlled shortterm consumption affects thyroid function.

METHODS

Eighty six volunteers--university students (32 males and 54 females) were eating unprocessed boiled natural soybeans (2 g/kg body weight/day) for 7 consecutive days. Thyrotropin, free thyroid hormones, antibodies to thyroid peroxidase and to thyroglobulin, and actual levels of unconjugated major soy phytoestrogens, daidzein and genistein, were measured in sera collected before, at the end and one week after finishing soy meal consumption.

RESULTS

Both phytoestrogens increased significantly (p<0.0001) at the end of soy-diet and fell down after its termination nearly back to the initial values. No significant changes were found in female group, while in males a significant transitory increase of thyrotropin (p<0.0001) was recorded. When actual levels of phytoestrogens were related to thyroid parameters, the only significant correlations were found between basal levels of daidzein and thyrotropin, daidzein and antithyroglobulin at the end of soy consumption in males, and between daidzein and free thyroxine at the end of the soy ingestion in females.

CONCLUSION

Though only modest and transitory effects on thyroid parameters occurred after controlled short-term soy consumption, some actual thyroid hormone parameters do correlate with actual isoflavone levels.

Pharmacokinetics of the soybean isoflavone daidzein in its aglycone and glucoside form: a randomized, double-blind, crossover study

BACKGROUND

There are conflicting results in the literature on the bioavailability of isoflavones in the aglycone and the glucoside forms.

OBJECTIVE

The objective was to investigate the pharmacokinetics of the soy isoflavone daidzein (DAI) on oral administration of both the aglycone and glucoside form in a human intervention study. In addition, the pharmacokinetics of the bacterial and oxidative metabolites of DAI was assessed.

DESIGN

Seven German men aged 22-30 y participated in a randomized, double-blind study in a crossover design. After ingestion of pure DAI or pure daidzein-7-O-beta-d-glucoside (DG) (1 mg DAI aglycone equivalent/kg body weight), blood samples were drawn before isoflavone administration and 1, 2, 3, 4.5, 6, 8, 10, 12, 24, and 48 h after the dose. Urine was collected before and 0-6, 6-12, and 12-24 h after the intake of the isoflavones. The concentrations of DAI and its major bacterial and oxidative metabolites in plasma and urine were measured with isotope dilution capillary gas chromatography-mass spectrometry.

RESULTS

The systemic bioavailability (area under the curve; AUC(inf)), the maximal plasma concentration (C(max)), and the cumulative recovery of DAI in urine after administration of DG were 3-6 times greater than after the ingestion of DAI. Except for equol, which was formed by only one volunteer, all other quantified metabolites exhibited 2-12 times greater AUC(inf), C(max), and urinary recoveries after consumption of DG.

CONCLUSION

Our results show that DG exhibits a greater bioavailability than its aglycone when ingested in an isolated form.

Dietary phytoestrogens activate AMP-activated protein kinase with improvement in lipid and glucose metabolism

OBJECTIVE

Emerging evidence suggests that dietary phytoestrogens can have beneficial effects on obesity and diabetes, although their mode of action is not known. Here, we investigate the mechanisms mediating the action of dietary phytoestrogens on lipid and glucose metabolism in rodents.

RESEARCH DESIGN AND METHODS

Male CD-1 mice were fed from conception to adulthood with either a high soy-containing diet or a soy-free diet. Serum levels of circulating isoflavones, ghrelin, leptin, free fatty acids, triglycerides, and cholesterol were quantified. Tissue samples were analyzed by quantitative RT-PCR and Western blotting to investigate changes of gene expression and phosphorylation state of key metabolic proteins. Glucose and insulin tolerance tests and euglycemic-hyperinsulinemic clamp were used to assess changes in insulin sensitivity and glucose uptake. In addition, insulin secretion was determined by in situ pancreas perfusion.

RESULTS

In peripheral tissues of soy-fed mice, especially in white adipose tissue, phosphorylation of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase was increased, and expression of genes implicated in peroxisomal fatty acid oxidation and mitochondrial biogenesis was upregulated. Soy-fed mice also showed reduced serum insulin levels and pancreatic insulin content and improved insulin sensitivity due to increased glucose uptake into skeletal muscle. Thus, mice fed with a soy-rich diet have improved adipose and glucose metabolism.

CONCLUSIONS

Dietary soy could prove useful to prevent obesity and associated disorders. Activation of the AMPK pathway by dietary soy is likely involved and may mediate the beneficial effects of dietary soy in peripheral tissues.

Development of techniques for the analysis of isoflavones in soy foods and nutraceuticals

PURPOSE OF REVIEW

For over 20 years, soy isoflavones have been investigated for their ability to prevent a wide range of cancers and cardiovascular problems, and numerous other disease states. This research is underpinned by the ability of researchers to analyse isoflavones in various forms in a range of raw materials and biological fluids. This review summarizes the techniques recently used in their analysis.

RECENT FINDINGS

The speed of high performance liquid chromatography analysis has been improved, allowing analysis of more samples, and increasing the sensitivity of detection techniques allows quantification of isoflavones down to nanomoles per litre levels in biological fluids. The combination of high-performance liquid chromatography with immunoassay has allowed identification and estimation of low-level soy isoflavones. The use of soy isoflavone supplements has shown an increase in their circulating levels in plasma and urine, aiding investigation of their biological effects. The significance of the metabolite equol has spurned research into new areas, and recently the specific enantiomers have been studied.

SUMMARY

High-performance liquid chromatography, capillary electrophoresis and gas chromatography are widely used with a range of detection systems. Increasingly, immunoassay is being used because of its high sensitivity and low cost.

Long-term consumption of isoflavone-enriched foods does not affect bone mineral density, bone metabolism, or hormonal status in early postmenopausal women: a randomized, double-blind, placebo controlled study

BACKGROUND

Osteoporosis is a major health problem. It was hypothesized that isoflavone-containing products may be a potential alternative to hormone replacement therapy for preventing bone loss during the menopausal transition.

OBJECTIVE

The objective was to investigate whether the consumption of isoflavone-enriched foods for 1 y affects bone mineral density, bone metabolism, and hormonal status in early postmenopausal women.

DESIGN

This was a randomized, double-blind, placebo-controlled, parallel, multicenter trial. Two hundred thirty-seven healthy early postmenopausal women [mean (+/-SD) age of 53 +/- 3 y and time since last menses of 33 +/- 15 mo] consumed isoflavone-enriched foods providing a mean daily intake of 110 mg isoflavone aglycones or control products for 1 y while continuing their habitual diet and lifestyle. Outcome measures included bone mineral density of the lumbar spine and total body, markers of bone formation and bone resorption, hormones, isoflavones in plasma and urine, safety variables, and adverse events.

RESULTS

Consumption of isoflavone-enriched products did not alter bone mineral density of the lumbar spine and total body or markers of bone formation and bone resorption. Hormone concentrations did not differ between the isoflavone and control groups. Consumption of isoflavone-enriched products resulted in increased isoflavone concentrations in plasma and urine, whereas control products did not. This finding indicated good compliance with treatment. Subgroup analysis did not support an effect of equol phenotype on bone density. The intervention had no effect on a range of safety variables and reported adverse events.

CONCLUSION

Consumption of foods containing 110 mg/d of soy isoflavone aglycone equivalents for 1 y did not prevent postmenopausal bone loss and did not affect bone turnover in apparently healthy early postmenopausal white women. This trial was registered at clinicaltrials.gov as NCT00301353.

Age-stratified serum levels of isoflavones and proportion of equol producers in Japanese and Korean healthy men

Racial differences in the incidence of prostate cancer are manifest worldwide, possibly due to the different dietary habits. To elucidate the relationship between the recent trend of phytoestrogenic isoflavone intake and the increased incidence of prostate cancer in Japan, we conducted an age-stratified dietary survey of soybean foods in 102 Japanese healthy men (age range: 10-59 years) and measured the serum isoflavones and equol levels in them and 100 Korean healthy men. The intergroup comparison among the age-stratified groups showed significant differences in the daily intake of genistein and daidzein between the teenager group and the other groups of age >or=30 years (P<0.05). In the Japanese study, the proportion of equol producers in the teenager group was 10%, being significantly the lowest among the age-stratified groups. The proportions of equol producers in the age-stratified groups from 10 to 49 years were also significantly lower than those in the fifties. The equol non-producers consumed significantly less amounts of isoflavones than the equol producers. In the Korean study, the proportions of equol producers were 45% in the teenager and 40% in the twenties and thirties, being significantly lower than in the forties (80%) and fifties (65%). The decreased intake of isoflavones, low serum level of equol and low incidence of equol production in the young generation may become potential risk factors for prostate cancer not only in Japan but also in Korea in the near future. Elucidating the mechanism of equol production may be promising in developing strategies for chemoprevention against prostate cancer.

Preparation, characterization, and pharmacokinetic evaluation of puerarin submicron emulsion

A novel formulation of puerarin was studied. Puerarin submicron emulsion was prepared by complex phase inversion-high-pressure homogenization technology. Characterization, distribution of drug in emulsion, short-term stability, and pharmacokinetics of emulsion were evaluated. The mean diameter and zeta potential of puerarin emulsion were 188.14 nm and -29.45 mv, respectively. The distribution range of puerarin emulsion was very narrow. The concentration of puerarin in the interfacial surface, oil droplet, water, and liposome-micelles were 7.821, 1.079, 0.637 and 0.423 mg/mL, respectively. Puerarin submicron emulsion was stable for a period of 3 months. The area under the whole blood concentration-time curve of rabbits after intravenous administration of puerarin emulsion was 1.718-fold higher than that of rabbits of intravenous administration of puerarin (P < 0.05). And compared with the puerarin group, the elimination rate of puerarin emulsion group was significantly decreased (P < 0.05), and the biological half-life and the mean retention time of puerarin emulsion were markedly increased (P < 0.05).

Enhanced bioavailability of soy isoflavones by complexation with beta-cyclodextrin in rats

In order to improve the solubility and bioavailability of a soy isoflavone extract (IFE), inclusion complexes (IFE-beta-CD) of the isoflavone extract with beta-cyclodextrin (beta-CD) were prepared and studied for their solubility and bioavailability. The aqueous solubility of the complexes of IFE with beta-CD (2.0 mg/ml) was about 26 times that of IFE itself (0.076 mg/ml). The same dosages of IFE and IFE-beta-CD were orally administered to SD rats (Sprague-Dawley) on an isoflavone glycoside (IFG) basis (daidzin, genistin and glycitin), and the plasma concentrations of daidzein, genistein and glycitein were measured over time to estimate the average AUC (area under the plasma concentration versus time curve) of the isoflavones. After the oral administration, the AUC values for daidzein, genistein and glycitein were 340, 11 and 28 microg x min/ml, respectively. In contrast, the respective AUC values after the administration of IFE-beta-CD were 430, 20 and 48 microg x min/ml. The bioavailability of daidzein in IFE-beta-CD was increased to 126% by the formation of inclusion complexes with beta-CD, compared with that in IFE. Furthermore, the bioavailability of genistein and glycitein in IFE-beta-CD formulation was significantly higher by up to 180% and 170%, respectively, compared with that of IFE p=0.008 and p=0.028, respectively). These results show that the absorption of IFE could be improved by the complexation of IFE with beta-CD (IFE-beta-CD).

[Study on effect of different combinations of traditional Chinese medicine preparation active parts on metabolism of puerarin in plasma of rats]

OBJECTIVE

To build an experimental method to determine the content of puerarin in plasma, observe the effect of different combinations of traditional Chinese medicine preparation active parts on metabolism of puerarin in plasma of rats suffering cerebral ischemia attack after being orally administered the main active parts of Yangyin Tongnao granules.

METHOD

Absorption of puerarin in plasma was extracted by acetonitrile. Using hydroxybenzoate as interior standard, methanol-0.5% acetic acid water solution as mobile phase, ODS C(18) chromatography column (4.6 mm x 150 mm, 5 microm) as stationary phase, puerarin was detected at 248 nm.

RESULT

There is a good linear relationship for puerarin in the range 0.025-3.2 microg x mL-1, RSD < 10%, and the average recovery is 97.6%.

CONCLUSION

The method is sensitive, reliable, and can be well applied in this experiment. It can provide a method for determination of active components in TCM preparation in vitro. Different compatibility influences metabolism of components.

Endocrine disruptors and spontaneous premature labor: a case control study

BACKGROUND

Premature labor is a poorly understood condition. Estrogen is thought to play a key role and therefore the labor process may be affected by endocrine disruptors. We sought to determine whether or not an environmental toxicant, DDE, or dietary derived endocrine disruptors, daidzein and genistein, are associated with spontaneous preterm labor.

METHODS

Cases were defined as primiparous patients having a preterm delivery at or before 35 weeks following the spontaneous onset of labor. Controls were defined as primiparous women who delivered on the same day as the cases but at term gestation. Over approximately 1 year, 26 cases and 52 controls were recruited. Subjects agreed to have blood tests on day one postpartum for DDE and for the phytoestrogens genistein and daidzein.

RESULTS

The mean concentration of DDE was similar in the case and control groups: 4.29 vs 4.32 ng/g lipid p = .85. In the case group, 13/26 had detectable levels of daidzein (range 0.20 - 1.56 ng/ml) compared to 25/52 controls (range 0.21 - 3.26 ng/ml). The mean concentration of daidzein was similar in cases compared to controls: 0.30 vs .34 ng/ml p = 0.91. Of the case group,14/26 had detectable levels of genistein (range 0.20 - 2.19 ng/ml) compared to 32/52 controls (range 0.21 - 2.55 ng/ml). The mean concentration of genistein was similar in cases compared to controls: 0.39 vs 0.31 ng/ml, p = 0.61.

CONCLUSION

The serum levels of DDE in this population were found to be low. There appears to be no relationship between serum concentrations of DDE, daidzein, and genistein and spontaneous preterm labor in our population. The inability to identify an effect may be related to the comparatively low concentrations of DDE in our population and the rapid and variable reduction of phytoestrogens from women in labor.

LC–MS/MS method for the simultaneous determination of icariin and its major metabolites in rat plasma

A rapid and sensitive method using liquid chromatography-tandem mass spectroscopy (LC-MS/MS) was developed and validated for the simultaneous quantitative determination of icariin and its two major metabolites, icariside I and icariside II in rat plasma. The analytes were extracted by liquid-liquid extraction with ethyl acetate after internal standard (daidzein) spiked. The separation was performed by a ZORBAX SB-C(18) column (3.5 microm, 2.1 mm x 100 mm) and a C(18) guard column (5 microm, 4.0 mm x 2.0mm) with an isocratic mobile phase consisting of acetonitrile-water-formic acid (50:50:0.05, v/v/v) at a flow rate of 0.25 mL/min. The Agilent G6410A triple quadrupole LC-MS system was operated under the multiple reaction monitoring (MRM) mode using the electrospray ionization technique in positive mode. The nominal retention times for icariin, icariside I, icariside II and daidzein were 1.21, 1.88, 2.34 and 1.35 min, respectively. The lower limits of quantification (LLOQ) of icariin, icariside I and icariside II of the method were 1.0, 0.5 and 0.5 ng/mL, respectively. The method was linear for icariin and its metabolites with correlation coefficients >0.995 for all analytes. The intra-day and inter-day accuracy and precision of the assay were less than 12.5%. This method has been applied successfully to a pharmacokinetic study involving the intragastric administration of icariin to rats.

Increased probiotic yogurt or resistant starch intake does not affect isoflavone bioavailability in subjects consuming a high soy diet

OBJECTIVE

Probiotics and prebiotics that affect gut microflora balance and its associated enzyme activity may contribute to interindividual variation in isoflavone absorption after soy intake, possibly enhancing isoflavone bioavailability. This study examined the effects of the consumption of bioactive yogurt (a probiotic) or resistant starch (a known prebiotic) in combination with high soy intake on soy isoflavone bioavailability.

METHODS

Using a crossover design, chronic soy consumption was compared with soy plus probiotic yogurt or resistant starch in older male and postmenopausal females (n = 31). Isoflavone bioavailability was assessed at the beginning and end of each 5-wk dietary period by sampling plasma and urine after a standardized soy meal.

RESULTS

Chronic soy intake did not significantly affect plasma or urinary isoflavones after the soy meal and there were no significant effects of probiotic or resistant starch treatment. However, there were trends for increased circulating plasma daidzein and genistein after the probiotic treatment and for increased plasma daidzein and genistein 24 h after soy intake with resistant starch treatment. Neither treatment induced or increased equol production, although there was a trend for increased plasma equol in "equol-positive" subjects (n = 12) after probiotic treatment.

CONCLUSION

The weak or absence of effects of probiotic yogurt or resistant starch supplement to a chronic soy diet suggests that gut microflora were not modified in a manner that significantly affected isoflavone bioavailability or metabolism.

A phytoestrogen-rich diet increases energy expenditure and decreases adiposity in mice

BACKGROUND

Obesity is an increasingly prevalent health problem, and natural effective therapeutic approaches are required to prevent its occurrence. Phytoestrogens are plant-derived compounds with estrogenic activities; they can bind to both estrogen receptors alpha and beta and mimic the action of estrogens on target organs.

OBJECTIVES

The purpose of this study was to examine the influence of soy-derived phytoestrogens on energy balance and metabolism.

METHODS

Male outbred mice (CD-1) were allowed ad libitum access to either a high soy-containing diet or a soy-free diet from conception to adulthood. We measured circulating serum isoflavone levels using reverse-phase solid-phase extraction for subsequent liquid chromatography electrospray tandem mass spectrometry analysis. Adult animals were analyzed for body composition by dual-energy X-ray absorptiometry, locomotor activity by running-wheel experiments, respiratory exchange rate by indirect calorimetry, and food intake using metabolic cages. Quantitative reverse transcriptase-polymerase chain reaction was performed to determine the expression of hypothalamic neuropeptide genes.

RESULTS

We found that adult mice fed a soy-rich diet had reduced body weight, adiposity, and resistance to cold. This lean phenotype was associated with an increase in lipid oxidation due to a preferential use of lipids as fuel source and an increase in locomotor activity. The modulation of energy balance was associated with a central effect of phytoestrogens on the expression of hypothalamic neuropeptides, including agouti-related protein.

CONCLUSION

The data suggest that dietary soy could have beneficial effects on obesity, but they also emphasize the importance of monitoring the phytoestrogen content of diets as a parameter of variability in animal experiments.

[Pharmacokinetics of pueraria for intranasal on spray in rabbits]

OBJECTIVE

To explore pharmacokinetic features of puerarin in pueraria spray and calculate pharmacokinetic parameters according to puerarin of drug-time curve in rabbits.

METHODS

The concentration of puerarin in plamsa was determined by HPLC. The methanol was used to sediment protine. The 3P87 program was used to calculate the pharmacokinetic parameters.

RESULTS

The vivo course of pueraria in spray could be described by the two compartment model. The main pharmacokinetic parameters of Pueraria spray were: t(l/2(beta)) =0.93 h, CL =44.23 mg x L(-1), AUC = 16.28 mg x h x L(-1), Cmax =5.9 mg x L(-1) and tmax = 0.975 h.

CONCLUSION

The study will provide some scientific basises for the quality evaluation and pharmaceutics reformation of pueraria for intranasal.

Influence of inulin on plasma isoflavone concentrations in healthy postmenopausal women

BACKGROUND

Bacterial intestinal glucosidases exert an important role in isoflavone absorption. Insoluble dietary fibers such as inulin may stimulate the growth of these bacteria in the colon and, hence, stimulate the absorption of these substances in subjects who may need isoflavone supplementation.

OBJECTIVE

The objective was to assess the influence of inulin on plasma isoflavone concentrations after intake of soybean isoflavones in healthy postmenopausal women.

DESIGN

Twelve healthy postmenopausal women participated in a randomized, double-blind, crossover study. They consumed 40 mg of a conjugated form of soybean isoflavones (6 mg daidzein and 18 mg genistein as free form) with or without 3.66 g inulin twice daily in two 21-d experimental phases. Blood samples were collected 0, 1, 2, 3, 4, 6, 10, 12, and 24 h after intake of isoflavones with breakfast and dinner at the end of each 21-d experimental phase. Plasma concentrations of isoflavones were assessed by HPLC with an electrochemical detector.

RESULTS

Plasma 24-h areas under the curve indicated that the intake of soybean isoflavones with inulin for 21 d was followed by higher plasma concentrations of daidzein and genistein (38% and 91%, respectively) compared with the formulation without inulin. Furthermore, the time for the maximum concentration of daidzein and genistein appeared to be lower after the 21-d intake of soybean isoflavones, with or without inulin. However, the time for the maximum concentration of daidzein and genistein after supplementation with the inulin-containing formulation on day 21 was not significantly different from that after supplementation with the formulation without inulin.

CONCLUSIONS

Inulin may increase the apparent plasma concentrations of the soybean isoflavones daidzein and genistein in postmenopausal women. The higher plasma concentrations of the 2 isoflavones suggests that the absorption of each was facilitated by the presence of inulin.

Formulation optimization of self-emulsifying preparations of puerarin through self-emulsifying performances evaluation in vitro and pharmacokinetic studies in vivo

The main purpose of this work is to prepare self-emulsifying drug delivery system (SEDDS) of a poorly water soluble drug, puerarin. Solubility of puerarin was determined in various oils and surfactants. Oleic acid and Tween 80 provided higher solubility. Addition of propylene glycol as cosurfactant improved solubility of puerarin and the spontaneity of self-emulsification. A series of mixtures comprising oleic acid, propylene glycol and Tween 80 were prepared and their self-emulsifying properties were studied. Pseudo-ternary phase diagrams were constructed to identify the efficient self-emulsification region and particle sizes of the resultant emulsions were determined using a laser diffraction sizer. The pharmacokinetic behaviors of three different SEDDS formulations (F2, F3, F4) were investigated in Beagle dogs. The bioavailability was compared using the pharmacokinetic parameters, peak plasma concentration (C(max)), time to reach peak plasma concentration (T(max)) and total area under the plasma concentration-time curve (AUC(0-t)). AUC(0-t) was significantly higher in formulation F2 group (5.201 +/- 0.511) ng x mL(-1) x h and formulation F3 group (5.174 +/- 0.498) ng x mL (-1) x h than that in formulation F4 group (3.013 +/- 0.623) ng x mL(-1) x h. Also, C(max) was significantly higher in formulation F2 group (1.524 +/- 0.125) ng x mL(-1) and formulation F3 group (1.513 +/- 0.157) ng x mL(-1) than that in formulation F4 group (0.939 +/- 0.089) ng x mL(-1). Further analysis of the data showed a statistically significant difference between F2 and F4 (P < 0.01) as well as F3 and F4 (P < 0.01) with regard to the values of AUC(0-infinity) and C(max) for three SEDDS formulations, but not between those of F2 and F3 (P > 0.05). From these studies, the SEDDS formulation containing oleic acid (17.5%), Tween 80 (34.5%) and propylene glycol (34.5%) (w/w) was selected as an optimized SEDDS formulation of puerarin. The data suggest the potential use of SEDDS to improve oral absorption of puerarin.

Differential effects of isoflavones on bone formation in growing male and female mice

Few studies have examined the effects of isoflavones on bone formation during growth period in male and female animals. In this study, the effects of daidzein or genistein on bone formation were assessed in immature male and female mice. Five-week-old male and female mice were divided respectively into 3 groups (n=8 per group) as follows: control group (C) fed a control diet (AIN-93G), daidzein group (D) fed a control diet containing 0.08% pure daidzein, and genistein group (G) fed a control diet containing 0.08% pure genistein. After 4 weeks, the male D group had a significantly higher bone mineral density (BMD) in whole body, lumbar spine, and femur than did the C group. On the contrary, BMD of the whole body and femur in the female D group was significantly lower than that in the C group. The BMD of the whole femur in the male G group also was significantly higher than for the C group. Histologic analysis revealed that the bone formation rate was significantly higher in the male D and G groups, and lower in the female D group compared with the C group. These results suggest that daidzein has a specific, sexually dimorphic effect on bone formation and BMD during growth period in mice.