Current trends in isolation, separation, determination and identification of isoflavones: A review

Red and blue light-specific metabolic changes in soybean seedlings

Red and blue artificial light sources are commonly used as photosynthetic lighting in smart farm facilities, and they can affect the metabolisms of various primary and secondary metabolites. Although the soybean plant contains major flavonoids such as isoflavone and flavonol, using light factors to produce specific flavonoids from this plant remains difficult because the regulation of light-responded flavonoids is poorly understood. In this study, metabolic profiling of soybean seedlings in response to red and blue lights was evaluated, and the isoflavone-flavonol regulatory mechanism under different light irradiation periods was elucidated. Profiling of metabolites, including flavonoids, phenolic acids, amino acids, organic acids, free sugars, alcohol sugars, and sugar acids, revealed that specific flavonol, isoflavone, and phenolic acid showed irradiation time-dependent accumulation. Therefore, the metabolic gene expression level and accumulation of isoflavone and flavonol were further investigated. The light irradiation period regulated kaempferol glycoside, the predominant flavonol in soybeans, with longer light irradiation resulting in higher kaempferol glycoside content, regardless of photosynthetic lights. Notably, blue light stimulated kaempferol-3-O-(2,6-dirhamnosyl)-galactoside accumulation more than red light. Meanwhile, isoflavones were controlled differently based on isoflavone types. Malonyl daidzin and malonyl genistin, the predominant isoflavones in soybeans, were significantly increased by short-term red light irradiation (12 and 36 h) with higher expressions of flavonoid biosynthetic genes, which contributed to the increased total isoflavone level. Although most isoflavones increased in response to red and blue lights, daidzein increased in response only to red light. In addition, prolonged red light irradiation downregulated the accumulation of glycitin types, suggesting that isoflavone's structural specificity results in different accumulation in response to light. Overall, these findings suggest that the application of specific wavelength and irradiation periods of light factors enables the regulation and acquisition of specialized metabolites from soybean seedlings.

Antioxidant and Cytotoxic Activities of Kudzu Roots and Soy Molasses against Pediatric Tumors and Phytochemical Analysis of Isoflavones Using HPLC-DAD-ESI-HRMS

Pediatric solid tumors (PSTs) are life-threatening and can lead to high morbidity and mortality rates in children. Developing novel remedies to treat these tumors, such as glioblastoma multiforme and sarcomas, such as osteosarcoma, and rhabdomyosarcoma, is challenging, despite immense attempts with chemotherapeutic or radiotherapeutic interventions. Soy (Glycine max) and kudzu roots (KR) (Pueraria spp.) are well-known phytoestrogenic botanical sources that contain high amounts of naturally occurring isoflavones. In the present study, we investigated the antioxidant and cytotoxic effects of the extracts of KR and soy molasses (SM) against PSTs. The green extraction of isoflavones from KR and SM was performed using natural deep eutectic solvents. The extracts were subsequently analyzed by high-performance liquid chromatography (HPLC)-diode array detector (DAD) coupled with high-resolution (HR) mass spectrometry (MS), which identified 10 isoflavones in KR extracts and 3 isoflavones in the SM extracts. Antioxidant and cytotoxic activities of KR and SM extracts were assessed against glioblastoma multiforme (A-172), osteosarcoma (HOS), and rhabdomyosarcoma (Rd) cancer cell lines. The KR and SM extracts showed satisfactory cytotoxic effects (IC₅₀) against the cancer cell lines tested, particularly against Rd cancer cell lines, in a dose-dependent manner. Antioxidant activity was found to be significantly (p ≤ 0.05) higher in KR than in SM, which was consistent with the results of the cytotoxic activity observed with KR and SM extracts against glioblastoma and osteosarcoma cells. The total flavonoid content and antioxidant activities of the extracts were remarkably attributed to the isoflavone content in the KR and SM extracts. This study provides experimental evidence that HPLC-ESI-HRMS is a suitable analytical approach to identify isoflavones that exhibit potent antioxidant and anticancer potential against tumor cells, and that KR and SM, containing many isoflavones, can be a potential alternative for health care in the food and pharmaceutical industries.

A Comprehensive Review on the Electrochemical Sensing of Flavonoids

Flavonoids are bioactive polyphenolic compounds, widespread in the plant kingdom. Flavonoids possess broad-spectrum pharmacological effects due to their antioxidant, anti-tumor, anti-neoplastic, anti-mutagenic, anti-microbial, anti-inflammatory, anti-allergic, immunomodulatory, and vasodilatory properties. Care must be taken, since excessive consumption of flavonoids may have adverse effects. Therefore, proper identification, quantification and quality evaluations of flavonoids in edible samples are necessary. Electroanalytical approaches have gained much interest for the analysis of redox behavior and quantification of different flavonoids. Compared to various conventional methods, electrochemical techniques for the analysis of flavonoids offer advantages of high sensitivity, selectivity, low cost, simplicity, biocompatibility, easy on-site evaluation, high accuracy, reproducibility, wide linearity of detection, and low detection limits. This review article focuses on the developments in electrochemical sensing of different flavonoids with emphasis on electrode modification strategies to boost the electrocatalytic activity and analytical efficiency.

Quantitative analysis of nine isoflavones in traditional Chinese medicines using mixed micellar liquid chromatography containing sodium dodecylsulfate/β-cyclodextrin supramolecular amphiphiles

Isoflavone is one of the phytoestrogens that have estrogenic effects, so it is usually served as an active ingredient for quality control of traditional Chinese medicines rich in isoflavones. Nine isoflavones commonly found in traditional Chinese medicines were separated in 30 min using mixed micellar liquid chromatography. The mobile phase consisted of 0.08 M sodium dodecylsulfate and 6.05 mM β-cyclodextrin:methanol (87:13, v/v) at pH 3 and eluted isocratically at 1 mL/min through a C18 column. In this study, we systematically optimized the chromatographic conditions including the pH, the composition and concentration of surfactants, the type and ratio of organic solvents, and column temperature. The method was validated according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use guidelines. There is no report using micellar liquid chromatography to detect isoflavones, and the optimized method has been successfully applied to quantify isoflavones in red clover and Radix Puerariae. This method is efficient, cheap, and convenient. Finally, we verified the existence of supramolecular amphiphilic vesicles in the mobile phase by transmission electron microscopy to explain the increased chromatographic efficiency.

Carbon fibers as green and sustainable sorbent for the extraction of isoflavones from environmental waters

Isoflavones are a group of phytoestrogens of important environmental concern due to their endocrine disrupting effects. This article presents a rapid, green, and sustainable method for determining four isoflavones (daidzein, genistein, formononetin, and biochanin A) in environmental waters complying with current trends in Analytical Chemistry. The method consists of in-syringe dispersive solid-phase extraction (DSPE) as the extraction approach, using carbon fibers as extraction material. The synthesis of carbon fibers is simple and sustainable, since it only requires a natural product such as raw cotton as precursor, which is thermally treated (600 °C for 30 min) in an inert (Ar) atmosphere to convert it into carbon fibers. After extraction, the final eluate is analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The proposed methodology allows the determination of the four isoflavones in water samples at the ng L^-1 range, with limits of detection in the range from 17 to 25 ng L^-1, relative standard deviations (RSD) from 2.8 to 10.1%, and good batch-to-batch repeatability (RSD < 13%). The method was finally applied to six environmental water samples from different sources and two swimming pool waters, and concentrations of all analytes up to 490 ng L^-1 were found. The highest concentrations were found in those samples close to crop fields. Relative recovery values (80-121%) showed that the aqueous matrices considered in this work did not significantly affect the extraction process. This method overcomes the drawbacks of the previous works with the same purpose, such as consuming large volumes of organic solvents or prolonged extraction times. Moreover, this procedure would allow the extraction stage to be carried out in situ, since only the sorbent material (previously synthesized in the laboratory) and disposable syringes are required.

Optimization of the Bioactivation of Isoflavones in Soymilk by Lactic Acid Bacteria

Soybeans and soy-based products contain isoflavones which can be used for nutraceutical and medical applications. In soybeans and in unfermented soy foods, isoflavones are normally present as glycosides. Isoflavone glycosides can be enzymatically converted to isoflavone aglycones, thus releasing the sugar molecule. The effective absorption of isoflavones in humans requires the bioconversion of isoflavone glycosides to isoflavone aglycones through the activity of the enzyme β-glucosidase. The objective was to assess the capacity of 42 bacterial strains (belonging to Lactobacillus, Streptococcus and Enterococcus) to produce β-glucosidase activity. The strain that showed the highest β-glucosidase activity (Lactobacillus plantarum 128/2) was then used for the optimization of the bioconversion of genistin and daidzin present in commercial soymilk to their aglycone forms genistein and daidzein. The contribution of process parameters (temperature, inoculum size, time) to the efficiency of such bioactivation was tested. Lactobacillus plantarum 128/2 was able to completely bioactivate soymilk isoflavones under the following conditions: 25 °C temperature, 2% inoculum size and 48 h process time. These results confirm the suitability of lactic acid bacteria for the bioactivation of isoflavones present in soymilk and provide an interesting candidate (L. plantarum 182/2) for food industries to perform this transformation.

Screening of Novel Source for Genistein by Rapid and Sensitive UPLC-APCI-TOF Mass Spectrometry

Genistein has been shown to have a broad spectrum of health advantages. Only legumes were reported to have a significant amount of genistein with the highest concentration in Soybean. Soybean was found to cause allergies in children with atopic dermatitis and in adults. Limited food sources have hindered the use of genistein in daily diets, medications, and nutraceuticals. The main objective of the current research work was to discover the novel source for genistein by the simple method of extraction and quantification. Genistein was extracted by solid-liquid extraction technique. Extraction parameters were optimized by a single factor test. Identification and quantification of genistein from the selected seeds of Apiaceae were carried out using UPLC-APCI-TOF-MS. UPLC-APCI-TOF-MS method was successfully developed, validated (linearity (R² = 0.999), precision (R.S.D. <5%), and accuracy (107.23%)), and used for the study. Remarkably, a high concentration of the genistein (811.57 μg/g) was found in the Cuminum cyminum. Solvent mixture (50 mL Methanol+25 mL Dimethyl sulphoxide+25 mL Water (v/v/v)), temperature (80°C), and time (1 h) were found to be the optimum extraction conditions. The concentration of genistein before optimization was 226.67 μg/g and after optimization is 811.57 μg/g. This shows the efficiency of the extraction method in the extraction of genistein without the need for hydrolysis. Novel source for genistein is identified in regular human food can be consumed in a regular diet which increases wellness of human health along with enhancing the taste of the food. The developed extraction method coupled with high throughput, sensitive, and selective UPLC-APCI-TOF-MS technique facilitates rapid quantification (8 minutes of run time) without primary purification of complex extract.

A brief history and spectroscopic analysis of soy isoflavones

The production of soybean continues to increase worldwide. People are showing more interest in the beneficial health effects of soybeans than before. However, the origin and history of soybeans are still being discussed among many researchers. Chromatographic methods enable the desirable separation of a variety of isoflavones from soybeans. The structures of isolated soy isoflavones have been successfully identified in tandem with spectroscopic analytical instruments and technologies such as liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy. The theoretical background behind spectroscopy may help improve the understanding for the analysis of isoflavones in soybeans and soy-derived foods. This review covers the origin of the English name of soybean and its scientific name, Glycine max (L.) Merrill, based on the evidence reported to date. Moreover, the reports of soy isoflavones discovered over a period of about 100 years have been briefly reviewed.

Fermentation of plant-based milk alternatives for improved flavour and nutritional value

Non-dairy milk alternatives (or milk analogues) are water extracts of plants and have become increasingly popular for human nutrition. Over the years, the global market for these products has become a multi-billion dollar business and will reach a value of approximately 26 billion USD within the next 5 years. Moreover, many consumers demand plant-based milk alternatives for sustainability, health-related, lifestyle and dietary reasons, resulting in an abundance of products based on nuts, seeds or beans. Unfortunately, plant-based milk alternatives are often nutritionally unbalanced, and their flavour profiles limit their acceptance. With the goal of producing more valuable and tasty products, fermentation can help to the improve sensory profiles, nutritional properties, texture and microbial safety of plant-based milk alternatives so that the amendment with additional ingredients, often perceived as artificial, can be avoided. To date, plant-based milk fermentation mainly uses mono-cultures of microbes, such as lactic acid bacteria, bacilli and yeasts, for this purpose. More recently, new concepts have proposed mixed-culture fermentations with two or more microbial species. These approaches promise synergistic effects to enhance the fermentation process and improve the quality of the final products. Here, we review the plant-based milk market, including nutritional, sensory and manufacturing aspects. In addition, we provide an overview of the state-of-the-art fermentation of plant materials using mono- and mixed-cultures. Due to the rapid progress in this field, we can expect well-balanced and naturally fermented plant-based milk alternatives in the coming years.

Increase in isoflavonoid content in Glycine max cells transformed by the constitutively active Ca2+ independent form of the AtCPK1 gene

Calcium-dependent protein kinases (CDPKs) represent a class within a multigene family that plays an important role in biotic and abiotic plant stress responses and is involved in the regulation of secondary metabolite biosynthesis. Our previous study showed that overexpression of the mutant constitutively active Ca2+ independent form of the AtCPK1 gene (AtCPK1-Ca) significantly increased the biosynthesis of anthraquinones and stilbenes in Rubia cordifolia L. and Vitis amurensis Rupr. transgenic cell cultures, respectively. Here, we have established transgenic calli of soybean plants Glycine max (L.) Merr. that express the AtCPK1-Ca gene. Heterologous expression of the AtCPK1-Ca gene provoked a 5.2-fold increase in total isoflavone production up to 208.09 mg/L, along with an increase in isoflavone aglycones production up to 6.60 mg/L, which is 3-fold greater than that of the control culture. The production of prenylated isoflavones significantly increased, reaching 3.78 mg/L, 13-fold higher than in the control culture. The expression levels of 4-coumarate:CoA ligases, isoflavone synthases, 2-hydroxyisoflavanone dehydratase, isoflavone dimethylallyltransferase, and coumestrol 4-dimethylallyltransferase genes in transgenic cell cultures significantly increased. Thus, heterologous expression of the AtCPK1-Ca gene can be used to bioengineer plant cell cultures that produce isoflavonoids.

Soy Isoflavones and their Effects on Xenobiotic Metabolism

BACKGROUND

Soy isoflavones, such as genistein and daidzein, are bioflavonoids found in soy products that are able to interact with various hormones such as estrogen. Epidemiological studies reveal a proper level of isoflavones in diet can prevent many diseases like cancers or diabetes. Therefore, it is important to study the biotransformation and xenobiotic metabolism of soy isoflavones.

METHODS

A systematic review of published studies was carried out to investigate the characterization of isoflavones and their metabolites, sample pretreatment and quantitative analysis of isoflavones, and the influence of soy isoflavones on drug and xenobiotic metabolism.

RESULTS

Aglycones with weak estrogen-like activities are the biologically active forms of the soy isoflavones in mammals. The most recent advances including extraction, purification and detection of isoflavones in soybean and soy products are discussed. The effects of soy isoflavones on drug and xenobiotic metabolism involve in regulation of phase I cytochrome P450 (CYPs) enzyme and phase I detoxifying enzymes expression and activity. At the molecular level, soy isoflavones have proved capable of estrogenic/antiestrogenic with tissue-selective, anti-cancer, antiobesity, anti-oxidation, and tyrosine kinase inhibition activities.

CONCLUSION

This review summarized different aspects of soy isoflavones and their molecular mechanisms of pharmacological action on xenobiotic, which demonstrated that soy isoflavones can decrease the incidence of many diseases and benefit for human health. However, since the lack of clinical research for evaluation of the proper dosage of intake of soy isoflavones in diet or adjunctive therapy, there is a need for further studies on the selection of doses, biomedical applications and adverse effects of isoflavones for human health.

Attenuation of utero-toxicity, metabolic dysfunction and inflammation by soy protein concentrate in rats exposed to fluoridated water: consequence of hyperlipidemia in parallel with hypohomocysteinemia

Lipid peroxidation and ROS generation are the pathogenesis of chronic fluoride toxicity, and its detrimental effects on human reproduction are noted drastically. The aim of the present study was to elucidate the defensive effects of soy protein concentrate (SPC) against sodium fluoride (NaF)-induced uterine dysfunction at biochemical and histological level. Rats were randomly distributed into four groups as control, NaF-treated (200 ppm), and SPC co-administered groups (20 mg and 40 mg/ 100 g body weight) for 16 days. SPC reversed the toxic effects of NaF. SPC significantly ameliorated the NaF-induced alterations of the antioxidant system in the uterus by decreasing lipid peroxidation products and by increasing antioxidant activities. SPC significantly counteracted the adverse effects of NaF on serum level of lactate dehydrogenase (LDH) and inflammatory markers Interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α) and nuclear factor kappa-B (NF-κB). Our results also explored that lipid profile was meaningfully altered due to NaF and also focused a diminution of circulating homocysteine (Hcy) and altered lipid profiles along with a diminished quantity of serum B₁₂ and B₉. However, both the doses of SPC reverted back serum levels of B₁₂, B₉, and Hcy status in similar fashion along with its corrective action on lipid profile. NaF-treated group exhibited a marked degree of reduction in the weights of ovary and uterus with an alteration of normal tissue histology and significant diminution in serum estradiol (ES) levels without fluctuating uterine estradiol receptor-α (ER-α). However, SPC restored the normal tissue histoarchitecture and also increased the functional efficiency and expression of the ER-α receptor by overturning the ES levels in NaF-treated rats. Moreover, both the doses of SPC were effective against NaF-induced alterations, although 40 mg SPC/100 g body weight had better efficacy in ameliorating the NaF-induced adverse effects on the uterus and ovary.

Enzymatic modification of daidzin using heterologously expressed amylosucrase in Bacillus subtilis

Amylosucrases (ASase, EC 2.4.1.4) from Deinococcus geothermalis (DGAS) and Neisseria polysaccharea (NPAS) were heterologously expressed in Bacillus subtilis. While DGAS was successfully expressed, NPAS was not. Instead, NPAS was expressed in Escherichia coli. Recombinant DGAS and NPAS were purified using nickel-charged affinity chromatography and employed to modify daidzin to enhance its water solubility and bioavailability. Analyses by LC/MS revealed that the major products of transglycosylation using DGAS were daidzein diglucoside and daidzein triglucoside, whereas that obtained by NPAS was only daidzein diglucoside. The optimal bioconversion conditions for daidzein triglucoside, which was predicted to have the highest water-solubility among the daidzin derivatives, was determined to be 4% (w/v) sucrose and 250 mg/L daidzin in sodium phosphate pH 7.0, with a reaction time of 12 h. Taken together, we suggest that the yield and product specificity of isoflavone daidzin transglycosylation may be modulated by the source of ASase and reaction conditions.

Isoflavonoids as wound healing agents from Ononidis Radix

ETHNOPHARMACOLOGICAL RELEVANCE

Dried roots of Ononis spinosa L. are traditionally used for their diuretic, anti-inflammatory and wound healing effects.

AIM OF THE STUDY

Isolation of the bioactive compounds of Ononis spinosa L. subsp. leiosperma (Boiss.) Sirj.

MATERIALS AND METHODS

Ethyl acetate extract prepared from the roots of Ononis spinosa L. subsp. leiosperma (Boiss.) Sirj. was subjected to silica gel column. The fractions were tested for their wound healing and anti-inflammatory activities. Linear incision and circular excision wound models and hydroxypyroline estimation assay were used for the wound healing activity. Carrageenan-induced hind paw edema, TPA-induced ear edema and acetic acid-induced increase in capillary permeability tests as acute inflammation; FCA-induced arthritis as chronic inflammation models were used for the assessment of anti-inflammatory activity. Antioxidant capacities of the fractions were tested using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, 2,2-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) scavenging activity assay, reducing power assay and hydroxyl radical (OH^-) scavenging assay. The isolation procedure was continued with the active fraction (Fr-E5).

RESULTS

Fr-E5 exhibited remarkable wound healing activity with the 33.4% tensile strength value on the linear incision wound model and 51.4% reduction of the wound area at the day 12 on the circular excision wound model. Hydroxyproline content of the tissue treated by Fr-E5 was found to be 30.9 ± 0.72μg/mg. Acetic acid induced increase in capillary permeability test results revealed that Fr-E5 inhibited inflammation by the value of 40.3%. Fr-E5 showed 28.1-32.2% inhibition in carrageenan-induced hind paw edema test while did not possess activity on TPA-induced ear edema and FCA-induced arthritis models. Trifolirhizin, ononin, medicarpin-3-O-glucoside, onogenin-7-O-glucoside and sativanone-7-O-glucoside were isolated from Fr-E5 and tested for their wound healing activities using by measuring their inhibition of hyaluronidase, collagenase and elastase enzymes. Ononin and sativanone-7-O-glucoside inhibited hyaluronidase and elastase enzymes by 31.66% and 41.75%; 45.58% and 46.88% values respectively at the dose of 100μg/mL.

CONCLUSION

Among five isolated compounds, ononin and sativanone-7-O-glucoside were found to inhibit hyaluronidase and elastase enzymes. According to the results, these compounds may majorly be responsible for the wound healing activity of the extract.

Simple, efficient and economical methods for isolation and estimation of novel isoflavone using RP-HPLC

The study was undertaken to develop a simplified procedure for the isolation of bioactive isoflavone from Iris kashmiriana, using a direct method of isolation, avoiding the use of chromatographic techniques. The compound was isolated by commercially viable procedure. The extraction of powdered drug (500 g) was done with petroleum ether (60–80) using a Soxhlet apparatus (24 h run). The petroleum ether extract (gums and resins 2.13 g) was obtained and the marc (400 g) was subjected to extraction with 95% methanol using a Soxhlet apparatus (24 h run). The methanolic extract (5 g) was subjected to successive fractionation with toluene, chloroform and ethyl acetate and n- butanol. On the basis of phytochemical analysis, the glycoside was present in n- butanol fraction. The n-butanol fraction (1.5 g) was taken in dried methanol, passed through activated animal charcoal and subjected to acid hydrolysis. The isoflavone (250 mg), was obtained after the usual process of separation. The purity of the compound was checked by analyzing TLC (Thin Layer chromatography) and melting point. Further, the chemical method was used to characterize the compound by shift reagents using UV spectroscopy. The quantitative estimation of isoflavone was done using RP-HPLC and was found to be 98.9% pure.

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The “previously undescribed” isoflavone was isolated by modifying approach of solvent/solvent extraction, fractionation and acid hydrolysis.

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The spectroscopic characterization was equaly done by IR, ¹HNMR, ¹³CNMR, Mass spectrometry.

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98.9% purity was achieved using RP-HPLC with simple solvent (Methanol and Water 55: 45).

Liquid chromatography with absorbance detection and with isotope-dilution mass spectrometry for determination of isoflavones in soy standard reference materials

Two independent analytical approaches, based on liquid chromatography with absorbance detection and liquid chromatography with mass spectrometric detection, have been developed for determination of isoflavones in soy materials. These two methods yield comparable results for a variety of soy-based foods and dietary supplements. Four Standard Reference Materials (SRMs) have been produced by the National Institute of Standards and Technology to assist the food and dietary supplement community in method validation and have been assigned values for isoflavone content using both methods. These SRMs include SRM 3234 Soy Flour, SRM 3236 Soy Protein Isolate, SRM 3237 Soy Protein Concentrate, and SRM 3238 Soy-Containing Solid Oral Dosage Form. A fifth material, SRM 3235 Soy Milk, was evaluated using the methods and found to be inhomogeneous for isoflavones and unsuitable for value assignment. Graphical Abstract Separation of six isoflavone aglycones and glycosides found in Standard Reference Material (SRM) 3236 Soy Protein Isolate.

Multidimensional Effects of Soy Isoflavone by Food or Supplements in Menopause Women: A Systematic Review and Bibliometric Analysis

Isoflavones can exert their action on various levels: on cardiovascular system, bone and muscle health, on cancer, on menopausal symptoms, on obesity, on thyroid and on cognitive function. The aim of this systematic review is to evaluate the multidimensional effects of phytoestrogens in postmenopausal woman, and specifically to explore the impact on scientific literature. A research strategy was planned on PubMed and Scopus by defining the following key words:: menopause, climacteric, soy, isoflavone, phytoestrogens, cardiovascular system, bone mineral density, muscle mass, cancer, thyroid, obesity, cognitive. A total of 43 studies (in humans) were retrieved. The majority (12) describe the applications of soy isoflavones on cardiovascular disease, followed by effects on bone and muscle health (9), and studies concerning their action on menopausal symptoms (7), on cancer (6), on obesity (4), on cognitive function (3) and on thyroid function (2). The citation analysis revealed a growing interest for this topic and the papers on thyroid function are the most cited. Citation trends of the articles regarding the action on cardiovascular disease and on obesity are growing in the last years. Concerning the research areas, this review has assessed the effectiveness of various activities of isoflavones on welfare of menopausal women. In particular, literature show that a specific dosage of isoflavones reduces cardiovascular disease (from 20 to 100 mg/die), may be protective in osteoporosis and muscular fatigue (from 20 to 80 mg/die), may be useful for cancer prevention on endometrium, mammary glands and liver (from 50 to 100 mg/die), might improve menopausal symptoms, particularly in reducing the frequency of hot flashes (from 50 to 120 mg/die), can reduce abdominal fat and circulating inflammatory markers (from 80 to 160 mg/die), may ameliorate the possible interaction between endogenous estrogen and thyroid function (75 mg/die) and improve visual memory (from 50 to 100 mg/die).

Analytical methods used to quantify isoflavones in cow's milk: a review

This paper provides an update and comprehensive review of the analytical methods used for quantifying isoflavones and their metabolites in cow’s milk. Isoflavones are secondary plant metabolites that are similar to 17 β-estradiol in chemical structure. They form one of the most common categories of phytoestrogens. Numerous health benefits have been attributed to isoflavones, but many of these compounds are also considered to be endocrine disruptors, with adverse effects on health. These contradictory trends offer an attractive prospect for future research, and therefore, sensitive and reliable analytical methods are required to clarify various issues about isoflavones. For this review, a structured methodology was used to select 26 relevant articles published between 2005 and 2015 from the Scopus and CAB Abstract databases. The review discusses individual steps of the analytical procedures described in these articles, including sample preparation, instrumental analysis and validation. The most commonly used analytical procedure is sample preparation involving liquid-liquid extraction and an enzymatic hydrolysis step followed by liquid chromatography with mass spectrometry analysis. Currently, however, there is no standardized procedure for the sample preparation and analysis of isoflavones in milk.

Determination of Isoflavone Content in SRM 3238 Using Liquid Chromatography-Particle Beam/Electron Ionization Mass Spectrometry

The characterization of marker components in botanical materials is a challenging task, and the increased consumption of botanicals and dietary supplements demands a greater understanding of the associated health benefits and risks. In order to successfully acquire and compare clinical results and correlate health trends, accurate, precise, and validated methods of analysis must be developed. Presented here is the development of a quantitative method for the determination of soy isoflavones (daidzin, glycitin, genistin, daidzein, and genistein) using LC-particle beam/electron ionization-MS (LC-PB/EIMS). An internal standard (IS) approach for quantitation with 7-hydroxy-4- chromone as the IS compound was used, with response factors for each individual isoflavone obtained from calibrant solutions. The results from this method were compared with the certified and reference values for National Institute of Standards and Technology (NIST) SRM 3238 Soy-Containing Solid Oral Dosage Form to demonstrate that the method was in control. Results obtained using LC-PB/EIMS were consistent with the NIST certified or reference values and their uncertainties for all five isoflavones, demonstrating that the LC-PB/EIMS approach is both accurate and precise when used for the determination of the target isoflavones in soy-containing dietary supplement finished products while simultaneously providing structural information.

Determination of free and bound phenolic compounds in soy isoflavone concentrate using a PFP fused core column

In the last years, the consumption of soy-based foods has increased due to the health benefits related to soy bioactives like phenolic compounds. Thus, in the present study, a new chromatographic method using reverse-phase high performance liquid chromatography coupled to diode array detection (RP-HPLC/DAD) was developed using a fused core pentafluorophenyl (PFP) column. The established method allowed the determination of twenty-one free phenolic compounds and eleven bound phenolics in a soy isoflavone concentrate. The method was validated in terms of precision and recovery. Intra and inter-day precision were less than 5% (% RSD) and the recovery was between 97.4% and 103.6%. Limits of quantification (LOQs) ranged between 0.093 and 0.443 μg/mL. Because of that, PFP stationary phase can be easily applied for routine determination of phenolic compounds in soy based foods.

Improving the estimation of flavonoid intake for study of health outcomes

Imprecision in estimating intakes of non-nutrient bioactive compounds such as flavonoids is a challenge in epidemiologic studies of health outcomes. The sources of this imprecision, using flavonoids as an example, include the variability of bioactive compounds in foods due to differences in growing conditions and processing, the challenges in laboratory quantification of flavonoids in foods, the incompleteness of flavonoid food composition tables, and the lack of adequate dietary assessment instruments. Steps to improve databases of bioactive compounds and to increase the accuracy and precision of the estimation of bioactive compound intakes in studies of health benefits and outcomes are suggested.

Effect of ultra high pressure homogenization treatment on the bioactive compounds of soya milk

Ultra high pressure homogenization (UHPH) is a useful novel technology to obtain safe and high-quality liquid foods. The effect of UHPH at 200 and 300 MPa in combination with different inlet temperatures (Tin) (55, 65 and 75 °C) on the bioactive compounds of soya milk was studied. Total phytosterols increased with the higher combination of pressure and temperature. The main phytosterol was β-sitosterol, followed by stigmasterol and campesterol. Total tocopherols in UHPH-treated soya milks decreased as the temperature and pressure increased. UHPH treatment also affected the different chemical forms of tocopherols. No biogenic amines were detected in any of the analyzed soya milks. Meanwhile, the polyamines SPD and SPM were found in all soya milks, being stable to the UHPH treatment. Total isoflavones increased with the higher combination of pressure and temperature. No differences in the isoflavone profile were found, with β-glucoside conjugates being the predominant form.

LC-MS metabolic study on quercetin and taxifolin galloyl esters using human hepatocytes as toxicity and biotransformation in vitro cell model

Galloyl esters of quercetin and taxifolin have been recently prepared semisynthetically as part of work towards modifying the solubility and modulating the biological activity of these natural flavonoids. In this paper we focused on the liquid chromatography-mass spectrometry (LC-MS) profiling of metabolites of 3-O-galloylquercetin and 7-O-galloyltaxifolin using human hepatocytes as the in vitro cell model. A subtoxic concentration (50μM) was used for both compounds and the formation of metabolites was monitored for 2h in hepatocytes and cultivation medium separately. Using negative electrospray ionization-quadrupole time-of-flight mass spectrometry (ESI-QqTOF MS), we identified different biotransformation patterns for the studied compounds. 3-O-Galloylquercetin is metabolized directly to glucuronides and methyl derivatives. In contrast, 7-O-galloyltaxifolin is oxidized to 7-O-galloylquercetin or cleaved to taxifolin, and consequently the products formed are sulfated or glucuronidated. The oxidative biotransformation of 3-O-galloylquercetin and 7-O-galloyltaxifolin is also accompanied by ester bond cleavage presumably by cellular enzymes (esterases) in a nonspecific manner. Our results provide fundamental insights into the biotransformation of monogalloyl esters of flavonoids and can be applied in investigations of the pharmaceutical potential of other galloylated polyphenolic substances.

Analytical strategies based on chromatography-mass spectrometry for the determination of estrogen-mimicking compounds in food

Food safety can be compromised by the presence of a wide variety of substances, deriving from both natural and anthropogenic sources. Among these substances, compounds exhibiting various degrees of estrogenic activity have been widely studied in environmental samples, whereas less attention has been devoted to food matrices. The aim of the present review is to give a general overview on the recent analytical methods based on gas or liquid chromatography coupled to mass spectrometry for the determination of estrogen-like compounds in foods, including new developments, improvements and upcoming trends in the field. Attention will be focused on four representative groups of compounds, i.e. natural and synthetic estrogens, mycoestrogens, phytoestrogens, and alkylphenols.

Apoptotic effects of cooked and in vitro digested soy on human prostate cancer cells

Previous laboratory and animal studies reported that soy isoflavones were major bioactive compounds in soy to exert chemoprotection of prostate cancer. However, these studies cannot reflect the realistic effects that soy may induce through diets, and little is known about the bioavailability of isoflavones from whole soy food and their bioactivities after cooking and digestion. In this study, cooking and in vitro digestion were used to prepare soy extracts and the effects of cooking and digestion on the isoflavone contents and bioactivities of the whole soy extracts were examined. The cooking procedure generally increased the amount of daidzin, genistin and daidzein, but decreased that of genistein. Digestion process significantly lowered contents of daidzin and genistin in 60min cooked sample, while increased the contents of daidzin and daidzein and decreased the content of genistein in the uncooked sample. Antioxidant activities of soy extracts increased after cooking and in vitro digestion, while no consistent increase of the four soy isoflavones was determined. The apoptotic effects of soy extracts on both LNCaP and C4-2B cells were generally in a dose-dependent manner. Compared to purified single isoflavones, cooked and digested soy were more effective on induction of prostate cancer cell apoptosis, which indicated synergistic interactions between various bioactive compounds in the whole soy.

Evaluation of matrix effect in determination of some bioflavonoids in food samples by LC-MS/MS method

In the present work the LC-MS/MS method with solid phase extraction for simultaneous determination of bioflavonoids rutin, quercetin, hesperidin, hesperetin and kaempferol in some food samples (red onion, orange peel and honey) was developed and the matrix effect accompanying this determination was quantified. The matrix effect evaluated using a postextraction addition method was found to be negative in the range -44 to -0.5%, indicating ionization suppression and strongly depended on bioflavonoid concentration. The observed matrix effect was explained taking into account the co-elution of phenolic acids, in terms of their acid-base and hydrophilic properties. The efficacy of extraction expressed as the absolute recoveries of flavonoids were 88-96%, indicating very good efficiency of extraction. The extracts of food samples obtained either by Soxhlet or ultrasonic extraction were analyzed for bioflavonoid content by the LC-MS/MS method in selected reaction monitoring mode using a triple quadrupole detector and standard addition method, which was found to be the most suitable calibration approach for these samples. The optimized separation was achieved on a Phenomenex Gemini C18 column with gradient elution and mobile phase composition A: 2% acetic acid in water and B: acetonitrile. R(s) values were in the range from 1.3 to 3.1, indicating good selectivity of the method. The obtained results (mg/100g fresh weight) for different bioflavonids were for rutin 0.16, for quercetin in the range 0.65-56, for hesperidin 0.016-24, for hesperetin 0.0068-36.4 and for kaempferol 0.14-1.63 and generally show good agreement with published data. Low detection limits (0.014-0.063 μg/mL) were obtained with acceptable recoveries (86-114%). Total time of analysis was less than 40 min, therefore the proposed method represents significant improvement over existing methods.

Phytoestrogens for menopausal symptoms: a review

OBJECTIVE

To review the evidence that isoflavones are effective treatments for menopausal symptoms and to present the safety data.

METHODS

The databases Scopus, ScienceDirect and Primo Central Index were searched and preference was given to systematic reviews and meta-analyses.

RESULTS

The available evidence suggests that isoflavones do not relieve menopausal vasomotor symptoms any better than placebo. Long-term safety studies suggest that women who consume a diet high in isoflavones may have a lower risk of endometrial and ovarian cancer.

CONCLUSIONS

Isoflavones cannot be recommended for the relief of hot flushes.