Quantitative determination of isoflavones and coumestrol in soybean by column liquid chromatography

Screening the effects of phytoestrogens on lipid metabolism in primary cultured adipocytes from rainbow trout (Oncorhynchus mykiss) and gilthead sea bream (Sparus aurata)

Aquafeed formulation has progressively reduced its dependence on fish-derived ingredients over the past decades. Plant-based substitutes have been a major focus, with soybean meal and its derivatives leading the way. However, many plants contain phytoestrogens, which may affect fish physiology. This study aimed to assess in vitro the effects of genistein (GE), daidzein (DZN), glycitein (GLY), and coumestrol (COU) on the lipid metabolism of rainbow trout (Oncorhynchus mykiss) and gilthead sea bream (Sparus aurata). Primary cultured adipocytes were incubated with these phytoestrogens, along with 17β-estradiol, at two doses each (1, 10, or 100 μM). The 100 μM dose of GE and DZN decreased adipocyte viability, and mainly enhanced lipid accumulation in both species, suggesting a hypertrophic condition. However, the reduction in adipocyte number and lipid content with 100 μM DZN in rainbow trout indicated a limiting effect on adipose tissue growth in this species. Interestingly, COU significantly increased cell viability in gilthead sea bream, potentially leading to hyperplastic growth, a more favorable metabolic state. In that species, which proved to be more phytoestrogens-sensitive, lipoprotein lipase was generally downregulated upon treatments. Moreover, 10 µM GE significantly decreased the mRNA levels of fatty acid transport protein 1 and fatty acid synthase, and increased those of fatty acid binding protein 1, suggesting an acceleration of the differentiation process compared to the control cells. This work provides new insights into how dietary phytoestrogens modulate fish lipid metabolism and supports that their presence in plant protein feedstuffs can potentially affect fish health and production performance.

From Plants to Therapies: Exploring the Pharmacology of Coumestrol for Neurological Conditions

Neurological disorders are possibly the most prevalent and have been identified to occur among individuals with autism beyond chance. These disorders encompass a diverse range of consequences with neurological causes and have been regarded as a major threat to public mental health. There is no tried-and-true approach for completely protecting the nervous system. Therefore, plant-derived compounds have developed significantly nowadays. Coumestrol (CML) is a potent isoflavone phytoestrogen with a protective effect against neurological dysfunction and has been discovered to be structurally and functionally similar to estrogen. In recent years, more research has been undertaken on phytoestrogens. This research demonstrates the biological complexity of phytoestrogens, which consist of multiple chemical families and function in various ways. This review aimed to explore recent findings on the most significant pharmacological advantages of CML by emphasising neurological benefits. Numerous CML extraction strategies and their pharmacological effects on various neurological disorders, including PD, AD, HD, anxiety, and cognitive impairments, were also documented.

Phytoestrogens as Biomarkers of Plant Raw Materials Used for Fish Feed Production

The intensive use of plant materials as a sustainable alternative for fish feed production, combined with their phytochemical content, which affects the growth and production characteristics of farmed fishes, necessitates their monitoring for the presence of raw materials of plant origin. This study reported herein concerns the development, validation and application of a workflow using high-performance liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) for the quantification of 67 natural phytoestrogens in plant-derived raw materials that were used to produce fish feeds. Specifically, we verified the presence of 8 phytoestrogens in rapeseed meal samples, 20 in soybean meal samples, 12 in sunflower meal samples and only 1 in wheat meal samples in quantities enabling their efficient incorporation into clusters. Among the various constituents, the soybean phytoestrogens daidzein, genistein, daidzin, glycitin, apigenin, calycosin and coumestrol, as well as the sunflower neochlorogenic, caffeic and chlorogenic phenolic acids, displayed the highest correlations with their origin descriptions. A hierarchical cluster analysis of the studied samples, based on their phytoestrogen contents, led to the efficient clustering of raw materials. The accuracy and efficiency of this clustering were tested through the incorporation of additional samples of soybean meal, wheat meal and maize meal, which verified the utilization of the phytoestrogen content as a valuable biomarker for the discrimination of raw materials used for fish feed production.

Effective methods for increasing coumestrol in soybean sprouts

Coumestrol (CM), a biologically active compound found in Leguminosae plants, provides various human health benefits. To identify easy and effective methods to increase CM content in vegetables, we developed a quantitative analysis method using high-performance liquid chromatography (HPLC). Using this method, we found that soybean sprouts (1.76 ± 0.13 μg/g) have high CM contents among nine vegetables and evaluated the difference in CM contents between two organs of the sprouts: cotyledons and hypocotyls. Next, soybean sprouts were cultivated under different light, temperature, and water conditions and their CM contents were evaluated. CM content was higher in hypocotyls (4.11 ± 0.04 μg/g) than in cotyledons. Cultivating soybean sprouts at 24°C enhanced CM content regardless of light conditions, the growth of fungi and bacteria, and sprout color. Thus, we identified methods of soybean sprout cultivation to increase CM content, which may provide health benefits and enhance value.

Encapsulation of isoflavone with milk, maltodextrin and gum acacia improves its stability

This study was carried out for extraction of soy isoflavones and entrapment of the isoflavones so obtained into whole milk via encapsulation techniques. Three different solvent (ethanol, methanol and acetonitrile) were used for the extraction of isoflavone using three stage of extraction. The extracted isoflavone was encapsulated into 200 ml of whole milk by spray drying using different concentrations of gum acacia (4, 6 and 8% w/v) and 10% w/v maltodextrin DE 18. The ratio between cores to coating materials was 1:10. Though acetonitrile extracted higher amount of isoflavone, ethanol was selected for subsequent studies of extraction of isoflavone, as per the legislations regarding use of Food-grade solvents. There was no significant difference (p > 0.5) among all three samples 4% gum acacia+10% maltodextrin (A), 6% gum acacia+10% maltodextrin (B) and 8% gum acacia+10% maltodextrin (C) in terms of moisture content and hygroscopicity. However, insolubility index showed that sample A possessed a higher solubility index. Encapsulation techniques suggested that sample A showed higher encapsulation efficiency than others. Statistical analysis suggested that there was no significant difference among samples A, B and C during storage at 4°C for the time period (30 days) studied, in terms of isoflavone retention rate. However, samples stored at 25 and 37°C showed significant difference in the retention rate. Among all the three samples, sample B showed significantly lower isoflavone degradation rate of 3.80, 4.07 and 4.70 × 10-3/day at 4, 25 and 37°C, respectively. The highest amount of isoflavone degradation was observed at 37°C. Results indicate that isoflavone can be encapsulated using a combination of gum acacia either 4 or 6% w/v and 10% maltodextrin along with milk proteins at 4°C for longer shelf life.

Synthesis, characterization and biological evaluation of formononetin derivatives as novel EGFR inhibitors via inhibiting growth, migration and inducing apoptosis in breast cancer cell line

Novel formononetin derivative 4v inhibited MDA-MB-231 cell proliferation, migration and induced apoptosis through targeting EGFR.

Analysis of isoflavones and coumestrol in soybean sprouts

High-performance liquid chromatography analysis is used to examine the distribution of isoflavones in different parts of soybean sprouts. Between the seed leaf and hypocotyl, the ratio of isoflavones differs depending on the aglycone type. Glycitein exists predominantly in the hypocotyl. Three compounds isolated from 4-day-old seed coats were identified as coumestrol and its glycosides.

Analytical and compositional aspects of isoflavones in food and their biological effects

This paper provides an overview of analytical techniques used to determine isoflavones (IFs) in foods and biological fluids with main emphasis on sample preparation methods. Factors influencing the content of IFs in food including processing and natural variability are summarized and an insight into IF databases is given. Comparisons of dietary intake of IFs in Asian and Western populations, in special subgroups like vegetarians, vegans, and infants are made and our knowledge on their absorption, distribution, metabolism, and excretion by the human body is presented. The influences of the gut microflora, age, gender, background diet, food matrix, and the chemical nature of the IFs on the metabolism of IFs are described. Potential mechanisms by which IFs may exert their actions are reviewed, and genetic polymorphism as determinants of biological response to soy IFs is discussed. The effects of IFs on a range of health outcomes including atherosclerosis, breast, intestinal, and prostate cancers, menopausal symptoms, bone health, and cognition are reviewed on the basis of the available in vitro, in vivo animal and human data.

Sample preparation for the analysis of isoflavones from soybeans and soy foods

This manuscript provides a review of the actual state and the most recent advances as well as current trends and future prospects in sample preparation and analysis for the quantification of isoflavones from soybeans and soy foods. Individual steps of the procedures used in sample preparation, including sample conservation, extraction techniques and methods, and post-extraction treatment procedures are discussed. The most commonly used methods for extraction of isoflavones with both conventional and "modern" techniques are examined in detail. These modern techniques include ultrasound-assisted extraction, pressurized liquid extraction, supercritical fluid extraction and microwave-assisted extraction. Other aspects such as stability during extraction and analysis by high performance liquid chromatography are also covered.

Atlantic salmon (Salmo salar L.) parr fed genetically modified soybeans and maize: Histological, digestive, metabolic, and immunological investigations

Physiological and health related responses to dietary inclusion of genetically modified (GM) full-fat soybean meal (Roundup Ready; GM-soy) and maize (MON810 Bt-maize; GM-maize), as well as non-parental, untransformed lines (nGM-soy and nGM-maize D2), were evaluated in farmed Atlantic salmon (Salmo salar L.) parr during the first 8 months of feeding. Significant effects of dietary GM presence were only found in intestinal Na+-dependent d-glucose uptake and SGLT1 protein level in the region pyloric caeca in which the highest values were found in the GM-soy, intermediate in the nGM-soy, and lowest in the standard FM fed groups. Data from this study confirm that GM soybeans (RRS) and maize (MON810) at inclusion levels of about 6% appear to be as safe as commercially available nGM soy and maize in diets for Atlantic salmon parr. Results from studies with higher inclusion levels and with non-modified, isogenic or near-isogenic parental lines as control groups are pending.

Short-term soybean intake and its effect on steroid sex hormones and cognitive abilities

OBJECTIVE

To observe the effects of short-term soybean consumption on cognitive spatial abilities and changes in sex endocrine net in both genders.

DESIGN

Short-term prospective intervention study.

SETTING

Academic medical center.

PATIENT(S)

Fifty-four healthy females and 32 healthy males (18 - 25 y of age).

INTERVENTION(S)

Volunteers were asked to eat 2 g/kg per day of soybeans during 1 week. Saliva and plasma samples were taken, and psychometric tests were performed on the 1st (before soybean intake), 7th (after soybean intake), and 14th days (after washout period) of the study.

MAIN OUTCOME MEASURE(S)

Salivary T and plasma E(2) were measured. Mental rotation (MR) and spatial visualization (SV) tests were performed on the days of sampling.

RESULT(S)

Soybean intake did not change salivary T and plasma E(2) levels in men. During the washout period, both parameters have shown a tendency to rise. The effect of soybean intake on hormonal parameters in men was, however, dependent on the basal T levels. In women, salivary T as well as plasma E(2) levels showed a tendency toward a decline after soybean intake (the decrease in E(2) was statistically significant) and to increase back toward basal levels during the washout period. Both males and females statistically significantly improved in MR and SV after soybean intake. During the washout period, both genders further improved their results in MR but not in SV.

CONCLUSION(S)

Short-term soybean consumption alters the concentrations of salivary T and plasma E(2) in both men and women. Spatial abilities appear to be improved by short-term soybean intake, but the exact mechanisms require further study.

Effects of coumestrol on neonatal and adult mice osteoblasts activities

Estrogen replacement therapy has been shown to reduce postmenopausal osteoporosis. In the present study, we examined the effects of the phytoestrogen coumestrol on neonatal and adult osteoblasts metabolism. Two different sources of osteoblast cells (neonatal mice calvaria and adult mice long bone) cultures were used in this study. The effects of coumestrol on the cellular activities were analyzed by the mitochondrial tetrazolium (MTT) assay, secretion of alkaline phosphatase (ALP), intracellular calcium content (Ca), and the gene expression of bone matrix protein, estrogen receptors (ER-alpha, ER-beta), and osteoprotegerin (OPG) and osteoprotegerin ligand (OPGL). The results showed that the proliferation of neonatal mice osteoblast cells was enhanced by treatment of coumestrol. In the presence of 10(-9)M coumestrol, the osteoblast proliferation attained 139.5% of the control and that the coumestrol can increase the intracellular calcium contents. Type I collagen gene expression was upregulated 167% at the 1st day's culture; ALP gene expression was upregulated 360% at the 7th day's culture; while the osteocalcin gene expression was upregulated 222% at the 14th day's culture. When adult mice osteoblasts were cultured in the presence of 10(-9)M coumestrol, the osteoblasts population increased significantly earlier and attained its maximal effect at the 21st day's culture with 207.4% of control group. The content of ER-beta and osteoprotegerin secretion by neonatal mice control cells gradually increased during osteoblasts differentiation, whereas the ER-alpha and OPGL content were decreased in this study. The cellular responses to the estradiol and counmestrol were quite different in the osteoblasts derived from different age.

Compositional changes induced by UV-B radiation treatment of common bean and soybean seedlings monitored by capillary electrophoresis with diode array detection

In this work, a new CE method with diode array detection (DAD) was developed for the monitoring and quantitation of flavonoids in different beans treated and untreated with UV-B radiation. Flavonoid concentration was monitored in UV-B-treated and untreated sprouts of three common beans (Zolfino ecotype, cv. Verdone, cv. Lingua di Fuoco) and one soybean (cv. Pacific). After acid hydrolysis of extracts, the CE-DAD method provides reproducible quantitative determinations of daidzein, glycitein, genistein, and kaempferol at ppm level in these natural matrices within a relatively short time (less than 16 min). Total flavonoid content determined by CE-DAD was 159 +/- 8, 26 +/- 2, 13 +/- 1, and 1.3 +/- 0.3 microg/g fresh weight for untreated sprouts of Pacific soybean, Verdone bean, Zolfino bean, and Lingua di Fuoco bean, respectively. UV-B treatment caused no significant quantitative effect on Pacific soybean sprouts, whereas it enhanced the total isoflavone content by 1.5, 1.8, and 3.2-fold in Verdone, Zolfino, and Lingua di Fuoco beans, respectively. The proposed method shows (i) the potentialities of bean sprouts as a natural source of bioactive compounds (antioxidants); (ii) the technological role of UV-B treatment for sprout isoflavone enrichment; and (iii) the good capabilities of CE-DAD to monitor this process.

Electrochemical valveless flow microsystems for ultra fast and accurate analysis of total isoflavones with integrated calibration

A novel strategy integrating methodological calibration and analysis on board on a planar first-generation microfluidics system for the determination of total isoflavones in soy samples is proposed. The analytical strategy is conceptually proposed and successfully demonstrated on the basis of (i) the microchip design (with the possibility to use both reservoirs), (ii) the analytical characteristics of the developed method (statically zero intercept and excellent robustness between calibration slopes, RSDs < 5%), (iii) the irreversible electrochemical behaviour of isoflavone oxidation (no significant electrode fouling effect was observed between calibration and analysis runs) and (iv) the inherent versatility of the electrochemical end-channel configurations (possibility of use different pumping and detection media). Repeatability obtained in both standard (calibration) and real soy samples (analysis) with values of RSD less than 1% for the migration times indicated the stability of electroosmotic flow (EOF) during both integrated operations. The accuracy (an error of less than 6%) is demonstrated for the first time in these microsystems using a documented secondary standard from the Drug Master File (SW/1211/03) as reference material. Ultra fast calibration and analysis of total isoflavones in soy samples was integrated successfully employing 60 s each; enhancing notably the analytical performance of these microdevices with an important decrease in overall analysis times (less than 120 s) and with an increase in accuracy by a factor of 3.

Development and validation of a RP-HPLC method for quantification of isoflavone aglycones in hydrolyzed soy dry extracts

Isoflavones are widely used as an alternative treatment to hormone replacement therapy and also for prevention of several chronic diseases, including cancers. Genistein, daidzein and glycitein are the most abundant isoflavone aglycones found in soy extracts, where they also occur as glycosides. This paper describes the development and validation of an isocratic reversed-phase HPLC (RP-HPLC) method for the analysis of isoflavone aglycones, released after acid hydrolysis of soy dry extracts, used as pharmaceutical raw material. The quantification was carried out in a C(18) endcapped column, using a mobile phase composed of 0.1% acetic acid and methanol (52:48), at a flow rate of 1.0 ml/min and diode array detection (DAD) at 254 nm. The method showed to be linear (r(2)>0.99), precise (R.S.D.<2%), accurate (recovery of 98.88% for daidzein and 98.12% for genistein), robust and specific.

Endocrine and cognitive effects of short-time soybean consumption in women

BACKGROUND

Soy phytoestrogens are known to influence the hormonal status acting as partial estrogen agonists. Soy-derived food supplements are advised for hormone replacement therapy, prevention of atherosclerosis, age-related cognitive decline and even hormone-dependent cancer, although results from clinical studies are controversial. Whether increased soybean intake can affect the endocrine status and cognitive abilities is largely unknown.

AIM

To observe the effects of 1 week of increased soybean intake on sex hormone levels and spatial cognitive abilities in women.

SUBJECTS AND METHODS

16 young healthy female volunteers were asked to eat 900 g of soybeans within 1 week. Salivary testosterone (T), free and total plasma T, salivary and plasma estradiol (E) were measured by radioimmunoassay before and after the study period. Mental rotation (MR) and spatial visualization (SV) psychological tests were done at the days of sampling.

RESULTS

Soybean intake increased total plasma T levels (p < 0.02) while decreasing salivary T (p < 0.01) and not altering free plasma T levels. Salivary and plasma E levels were not changed. The results of MR and SV tests were improved after the study period.

CONCLUSION

Short-time increased soybean intake alters the level of total plasma and salivary T and improves spatial cognition in women. Whether this effect is mediated by modulation of estrogen receptors, changes in sex hormone-binding globulin production or changes in activity of steroid-competent enzymes needs further study.

Determination of isoflavones in soybean food and human urine using liquid chromatography with electrochemical detection

A highly sensitive high-performance liquid chromatographic method with electrochemical detection (HPLC-ED) was developed for the determination of isoflavones. Electrochemical behaviour of daidzein and genistein was studied on carbon paste electrode (CPE) by adsorptive transfer stripping square wave voltammetry. The obtained electrochemical results were used for the development of HPLC-ED method. Furthermore, isoflavones were separated on an Atlantis dC18 column using a mobile phase consisting of acetonitrile (solvent A) and 0.15M acetate buffer of pH 5.5 (solvent B) at a flow rate 0.4 mL/min. A linear gradient profile (solvent B) was at 0-2 min 87%; 22 min 60%; 27 min 50%; 31 min 45%; 47 min 87%. Full scan of multi-channel coulometric detection was tested and optimal potential at 450 mV was chosen for our purposes. Calibration curves were linear (daidzein R(2) = 0.9993 and genistein R(2) = 0.9987). The detection limit for daidzein/genistein was 480/394 pg/mL (1.8/1.5 nM) and per column 2.4/1.9 pg. Isoflavones extracted from soybean products (farina, meat, milk) by the accelerated solvent extraction (ASE) procedure and isoflavones present in human urine were determined by the HPLC-ED method.

LC/UV/ESI-MS analysis of isoflavones in Edamame and Tofu soybeans

High-performance liquid chromatography coupled with ultraviolet and electrospray ionization mass spectrometry (HPLC/UV/ESI-MSD) was applied to the study of isoflavones in both Edamame and Tofu soy varieties, from which the immature fresh soybeans or the mature soybean seeds are consumed, respectively. Positive atmospheric pressure interface (API) MS and MS/MS were used to provide molecular mass information and led to the identification of a total 16 isoflavones, including three aglycones, three glycosides, two glycoside acetates, and eight glycoside malonates. The major isoflavones in soybean seeds were daidzein and genistein glycoside and their malonate conjugates. Trace levels of daidzein and genistein acetyl glycosides were found only in the mature dry soybean seeds. To facilitate quantitative analysis, acid hydrolysis during extraction of soy samples was selected to convert the various phytoestrogen conjugates into their respective isoflavone aglycones, allowing accurate quantitation of total phytoestrogens as aglycones. On the basis of HPLC combined with UV and MS detection, all three targeted soy isoflavone aglycones, daidzein, genistein and glycitein in hydrolyzed extracts were successfully quantified within 25 min with formononetin used as the internal standard. The standard curves of UV detection were fitted in the range of 14.16-29000 ng/mL for daidzein, 15.38-31500 ng/mL for genistein, and 11.72-24000 ng/mL for glycitein. For MS detection, the standard curves were established in the range of 3.54-1812.5 ng/mL for daidzein, 3.85-1968.75 ng/mL for genistein, and 2.93-1500 ng/mL for glycitein. Good linearities (r(2) > 0.999 for UV and r(2) > 0.99 for MS) for standard curves were achieved for each isoflavone. The accuracy and precision (RSD) were within 10% for UV detection and 15% for MS detection (n = 10). Using this method, the phytoestrogen levels of total isoflavone aglycones from 30 soybean seed varieties were then evaluated for confirmation of the technique. Total isoflavones ranged across the varieties from 0.02 to 0.12% in the Edamame varieties, which are harvested while the seeds are still immature, and from 0.16 to 0.25% in Tofu varieties, harvested when the seeds are physiologically mature. While the literature has focused on the isoflavone content of soy products and processing soy, this report provides a reliable analytical technique for screening of authenticated fresh immature Edamame soybeans and Tofu soybeans.

Trace determination of bisphenol A and phytoestrogens in infant formula powders by gas chromatography–mass spectrometry

This investigation describes a reliable and sensitive method for simultaneously determining bisphenol A (BPA) and two major phytoestrogens, daidzein and genistein, in powdered milks and infant formulas by gas chromatography-mass spectrometric analysis after trimethylsilylation. To reduce the matrix interference associated with the constituents of the formulas, the dissolved formula solutions were firstly ultra-centrifuged and the analytes in the supernatant were then extracted using a C18 solid-phase extraction column. The accuracy and precision of the method were determined and the technique was successfully employed to measure trace concentrations of BPA, daidzein and genistein in powdered formulas. The results show that BPA, daidzein and genistein were detected in all the testing samples (n = 6) at concentrations from 45 to 113 ng/g (except one infant formula), 20 to 2050 ng/g and 21 to 6510 ng/g, respectively. The highest concentrations of daidzein and genistein (i.e., 2050 and 6510 ng/g) were detected in a soy-based powdered infant formula. The quantitation limits were 1.0 ng/g for BPA, and 10 ng/g for daidzein and genistein using 0.5 g powdered milk samples.

Synthesis of hapten and conjugates of coumestrol and development of immunoassay

3-O-Carboxymethylcoumestrol was prepared as the hapten for immunoassay by a partial alkylation of coumestrol with ethyl chloroacetate in acetone alkalized with potassium carbonate. 3-O-Ethoxycarbonylmethylcoumestrol was separated by column chromatography and finally was hydrolyzed with formic acid. 1H and 13C NMR data (APT, COSY, HMQC, and HMBC) revealed that the reaction was regioselective, as 3-O-ethoxycarboxymethylcoumestrol was the only monosubstituted derivative. The hapten was then conjugated to bovine serum albumin and used for immunization of rabbits. A radioimmunoassay (RIA) system was established based on the polyclonal antiserum and a 125I-labeled hapten-tyrosine methyl ester conjugate as the radioligand. Parameters of the RIA: sensitivity: 12 pg per tube, 50% intercept: 140 pg per tube, working range: 20-4000 pg per tube. The cross-reactivity of a panel isoflavonoid and lignan phytoestrogens was either negligible (e.g. formononetin 0.07%; biochanin A 0.06%) or not detectable at all. The major immunoreactive peak in HPLC fractions from an alfalfa extract had the same retention time as coumestrol standard and represented 94.8% of the signal. The remaining 5.2% of immunoreactivity was distributed between five minor peaks. We conclude that after the validation for particular matrices, the method will be a useful tool for analysis of coumestrol, especially in low volume and low concentration samples.

Determination of daidzein and genistein in soybean foods by automated on-line in-tube solid-phase microextraction coupled to high-performance liquid chromatography

An automated on-line method for the determination of the isoflavones, daidzein and genistein, was developed using in-tube solid-phase microextraction coupled to high-performance liquid chromatography (in-tube SPME-HPLC). In-tube SPME is a new extraction technique for organic compounds in aqueous samples, in which analytes are extracted from the sample directly into an open tubular capillary by repeated draw/eject cycles of sample solution. Daidzein, genistein and their glucosides tested in this study were clearly separated within 8 min by HPLC using an XDB-C8 column with diode array detection. In order to optimize the extraction of these compounds, several in-tube SPME parameters were examined. The glucosides daidzin and genistin were analyzed as aglycones after hydrolysis because the glucosides were not concentrated by in-tube SPME. The optimum extraction conditions for daidzein and genistein were obtained with 20 draw/eject cycles of 40 microl of sample using a Supel-Q porous layer open tubular capillary column. The extracted compounds were easily desorbed from the capillary by mobile phase flow, and carryover was not observed. Using the in-tube SPME-HPLC method, the calibration curves of these compounds were linear in the range 5-200 ng/ml, with a correlation coefficient above 0.9999 (n = 18), and the detection limits (S/N = 3) were 0.4-0.5 ng/ml. This method was successfully applied to the analysis of soybean foods without interference peaks. The recoveries of aglycones and glucosides spiked into food samples were above 97%.

Differentiation of isomeric flavone/isoflavone aglycones by MS2 ion trap mass spectrometry and a double neutral loss of CO

The fragmentation behaviour of seven pairs of isomeric flavone/isoflavone aglycones (solely hydroxylated and/or methoxylated) was studied using ion trap mass spectrometry with atmospheric pressure ionisation (API, both electrospray and APCI) in the positive and negative ion modes. A major difference was found in the neutral loss of 56 u, which was a common feature of all isoflavones in API(+). It was identified as a double loss of CO by accurate mass tandem mass spectrometric (MS/MS) measurements using a hybrid quadrupole time-of-flight (Q-TOF) instrument. Fragmentation of daidzein with (13)C-isotope labelling of the carbon C2 showed that this double loss occurred from the central ring of the molecule. A mechanism for this selective fragmentation is given. Further isoflavone-specific fragmentations were used to develop a guideline for the identification of isoflavone structures. A software-based neutral loss scan of 56 u in the API(+)-MS(2) mode was applied to extracts of leaves of Lupinus albus and to soy flour. The structure elucidation guideline allowed identification of hydroxy and/or methoxy isoflavones. Structures could be confirmed for those available as reference compounds.

Determination of trace isoflavone phytoestrogens in biological materials by capillary electrochromatography

Capillary electrochromatography using a specialty monolithic matrix was utilized in developing a rapid and highly efficient separation of isoflavones in biological materials. Without a preconcentration technique, it is relatively easy to reach ppm-ppb concentrations of these compounds in soy-based foods and verify them structurally using a photodiode array detector. With on-column preconcentration, we were able to measure low-ppb levels in human serum. Using blood samples from human volunteers, whose diet was supplemented by a soy-based product, the method has been validated for high-throughput screening of isoflavones in clinical studies.

Review of the methods used in the determination of phytoestrogens

Interest in analytical methods for plant estrogens (phytoestrogens) has risen sharply in the past 10 years. In this review, we examine the existing analytical methods based on separations by gas-liquid chromatography, high-performance liquid chromatography and capillary electrophoresis in addition to methods of detection by ultraviolet absorption, fluorescence, electrochemical oxidation/reduction and mass spectrometry. These methods are compared with other methods of phytoestrogen analysis utilizing immunoassay approaches. The advantages and disadvantages of each of these methods are highlighted and potential areas for further development identified.

Identification and quantification of polyphenol phytoestrogens in foods and human biological fluids

We review the methods used to measure phytoestrogens (genistein, daidzein, lignans and their derivatives) in foods and biological fluids, and discuss advantages and disadvantages of each. The range of detection limits reported varies widely between individual laboratories, but generally the best reported sensitivity is as follows: immunoassay>HPLC-mass spectrometry=HPLC-multichannel electrochemical detection (coularray)>GC-single ion monitoring-mass spectrometry>HPLC-UV diode array>HPLC-single channel electrochemical detection. The best sensitivity reported so far is 0.002 pmol per assay for daidzein by radioimmunoassay. HPLC with UV diode array detection is the most commonly employed, but is the least sensitive and specific. GC and HPLC coupled with mass spectrometry or electrochemical detection are the most accurate and reproducible methods for a wide variety of analytes. Generally most methods, with the exception of immunoassay, have not been correlated with other methods. Recoveries from extraction methods, limits of detection, nature of compounds analysed and the internal standards used are summarised for more than 90 reports in the literature. From this data, it is clear that an inter-laboratory validation and correlation between a wide range of methods for phytoestrogen analysis is required. One underdeveloped area that requires particular attention is the analysis of plant lignans.

Analytical approaches for traditional chinese medicines exhibiting antineoplastic activity

Traditional Chinese medicines have attracted great interest in recent researchers as alternative antineoplastic therapies. This review focuses on analytical approaches to various aspects of the antineoplastic ingredients of traditional Chinese medicines. Emphasis will be put on the processes of biological sample extraction, separation, clean-up steps and the detection. The problems of the extraction solvent selection and different types of column chromatography are also discussed. The instruments considered are gas chromatography, capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) connected with various detectors (ultraviolet, fluorescence, electrochemistry, mass, etc.). In addition, determinations of antineoplastic herbal ingredients, including camptothecin, taxol (paclitaxel), vinblastine. vincristine, podophyllotoxin, colchicine, and their related compounds, such as irinotecan, SN-38, topotecan, 9-aminocamptothecin, docetaxel (taxotere) and etoposide, are briefly summarized. These drugs are structurally based on the herbal ingredients, and some of them are in trials for clinical use. Evaluation of potential antineoplastic herbal ingredients, such as harringtonine, berberine, emodin, genistein, berbamine, daphnoretin, and irisquinone, are currently investigated in laboratories. Other folk medicines are excluded from this paper because their antineoplastic ingredients are unknown.