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The conversion and deglycosylation of isoflavones and anthocyanins in black soymilk process

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Abstract

The conversion of isoflavones and anthocyanins during black soymilk processing including soaking and heating was investigated. During soaking procedure, the β-glucosidase activity, content of bioactive compounds including daidzein, genistein, delphinidin and cyanidin were significantly increased by deglycosylation reaction. After heating treatment at 90 °C for 1 h, the content of isoflavones β-glucosides including daidzin, glycitin and genistin were increased through a de-esterification reaction from malonyl-glucosides at high temperature. On the contrary, aglycone content including daidzein and genistein were no significant changed, this result indicated aglycones displayed well thermal stability. Moreover, anthocyanins including delphinidin-3-O-glucoside (D3G) and cyanidin-3-O-glucoside (C3G) were converted into delphinidin and cyanidin by glucose removal. HPLC analysis suggested that daidzein, genistein, D3G and C3G were bound with β-conglycinin and glycinin. Our results establish the conversion of bioactive components including daidzein, genistein, delphinidin and cyanidin by deglycosylation during soaking and heating progress and benefit to the production of soymilk.

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The aim of this study was to investigate the effects of soybean soaking on grain properties and isoflavone loss in order to find suitable conditions for this step of soybean processing. A moisture content of 120% (dry basis) was achieved by soaking the soybeans at 55 °C and 70 °C for 3 and 2 h, respectively. Soybeans soaked at temperatures above 25 °C showed no significant difference (p > 0.05) in hardness after 1 h of soaking. The contents of total isoflavones and soluble proteins were better preserved at soaking temperatures of 25 °C and 40 °C. The β-glucosidase activity and contents of aglycone and β-glucoside isoflavones were closely related. Soybeans soaked at 55 °C for 5 h had a 6-fold higher aglycone isoflavone content than did whole soybeans (81.4 μg aglycones g−1) without considerable impairment of the aforementioned characteristics; soaking under this condition is therefore recommended before subsequent processing. This work helps to estimate the loss in soluble protein content and the loss and degradation of isoflavones during soybean soaking at different temperatures.
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One anthocyanin compound, cyanin-3-glucoside, was isolated and identified by high performance liquid chromatography tandem mass spectrometry (HPLC_MS/MS) from seed coat of black soybean variety, Heizi to assess its thermal characterization in vitro. The thermal characterization of anthocyanin was studied by thermogravimetry (TG) analysis. The results from the TG curves showed the decomposition of anthocyanin occurred in three stages. Glucose cleaved from the cyanin-3-glucoside occurred in the first stage. Degradation of cyanin and small amounts of cyanin-3-glucoside appeared mainly in the second stage. The sugar in the anthocyanin was decomposed in the third stage. Thermodynamic analysis was applied by free dynamic model. TG-isothermal experiments for the anthocyanins from black soybean seed coats confirmed the correct of the thermodynamic analysis.
Article
In this study, electrospun soy protein isolate (SPI) nanocomposite fiber mats were developed utilizing the lowest concentration possible of poly(ethylene oxide) (PEO) containing the highest levels of anthocyanin-rich red raspberry (Rubus strigosus) extract [ARRE; 20% raspberry powder in 95% ethyl alcohol/water/85% lactic acid (80:19:1; v/v/v)]. Variations in the physicochemical attributes of SPI nanofiber mats were investigated as a function of adding ARRE before and after protein denaturation. The electrical conductivity of fiber-forming solutions significantly decreased with increasing ARRE. Scanning electron microscopy (SEM) imaging did not reveal noticeable overall microstructural morphological differences (seen as beads-on-fiber structures) but slightly altered the density of beads in the electrospun SPI fibers. Fourier transform infrared (FTIR) spectroscopy provided insights into the hydrogen bonding interactions between ARRE and SPI in relations to the processing methods used. Specifically, the addition of ARRE after denaturation of SPI caused the amide I bond at 1656 cm− 1 of SPI to dramatically increase, which indicates ARRE induced CO stretching vibration of soy protein, possibly due to the attachment of polyphenols in ARRE to the hydrophobic pockets of the soy protein side-chains. Simultaneously, the addition of ARRE after SPI denaturation imparts fiber forming solutions with a significant higher level of bioactive anthocyanins and a greater antibacterial activity against Staphylococcus epidermidis, this illustrates that anthocyanin-rich plant extracts could serve as new biological ingredients to create novel active/functionalized SPI-based nanomaterial in food systems.
Article
The number of cases of type 2 diabetes (T2D) is increasing worldwide. This disease can be characterized by insulin resistance and pancreatic β cell dysfunction, which lead to macro- and microvascular complications. Anthocyanins are flavonoids that occur naturally in plants and are responsible for their color. Studies with cell lines and animal models and clinical trials in humans suggest that anthocyanins exhibit antidiabetic properties. However, variation in the structure of anthocyanins makes it difficult to determine their effects on T2D. Understanding the absorption and metabolism of anthocyanins is important for understanding their role in the improvement of this disease. Published data suggest that anthocyanins may lower blood glucose by improving insulin resistance, protecting β cells, increasing secretion of insulin and reducing digestion of sugars in the small intestine. The mechanisms of action are primarily related to their antioxidant properties, but enzymatic inhibition and other pathways may also be relevant.
Article
An investigation was performed on the profile and the content of isoflavones in the concentrate of aqueous Defatted Soy Flour (DSF) extract obtained by nanofiltration. The effect of thermal treatments on these isoflavones was also evaluated according to a Central Composite Design (CCD 2k) with varying temperatures (70 to 90°C) and times (15 to 45min). Through nanofiltration it was possible to concentrate β-glucosides and malonyl glucosides (p0.05). The thermal treatments applied on the concentrate showed that the malonyl glucosides were influenced by temperature (p
Article
The water absorption of soybeans in soaking is directly related to the changes in textural characteristics and grinding properties of soybeans for processing. In this study, we determined the characteristics of water absorption, solid loss, and moisture content, textural characteristics and grinding properties of soybeans at four different soaking temperatures, 10°C, 20°C, 30°C, and 40°C, and various soaking times up to 8h. We found that the solid loss increased significantly when the soaking temperature increased from 30°C to 40°C. The measured moisture data of soaked soybeans fitted well with the data predicted using Peleg's equation. Rupture force and maximum tangent and secant modulus measured by the compression test decreased as the moisture increased, up to 122%. The grinding property of soaked soybeans was related only to the final moisture content and not to the soaking conditions. High soaking temperature could significantly reduce the required soaking time. Based on these results, we recommend that soybeans be soaked to minimal final moisture content of 120% before grinding.
Article
A rapid HPLC method was developed for determination of isoflavones in soybean. Twelve isoflavones were resolved within 15 min by using a Vydac 201TP54 C18 column and a mobile phase of acetonitrile (A) and water (B) with the following gradient elution: 8% A and 92% B initially, increased to 10% A in 2 min, 12% A in 3 min, 22% A in 10 min, 23% A in 11 min, 35% A in 12 min, 50% A in 13 min, maintained for 3 min, and returned to 8% A in 20 min. The flow rate was 2 mL/min with column temperature at 35°C and detection at 262 nm. Formononetin was found to be a suitable internal standard for quantification. A solvent system of acetone–0.1 mol/L hydrochloric acid (5:1, v/v) was used for extraction of isoflavones from soybean, and the recoveries ranged from 64–87%. The malonylglucosidic type of isoflavones was present in the largest amount, while the acetylglucosidic type showed the lowest level.
Article
Spent coffee grounds, discarded as environmental pollutants, were adopted as enzyme immobilisation solid carriers instead of commercialised solid supports to establish an economical catalytic system. β-Glucosidase was covalently immobilised onto spent coffee grounds for the conversion of isoflavone glycosides into their aglycones in black soymilk. Optimum conditions were determined to be 40°C and pH 6 using 4-nitrophenyl β-d-glucuronide as an indicator. Operational reusability was confirmed for more than 30 batch reactions and the storage stability was capable of sustaining its highest catalytic activity for 20days. The kinetic parameters including rate constant (K), time (τ50) in which 50% of isoflavone deglycosylation was reached, and time (τcomplete) required to achieve complete isoflavone deglycosylation, were0.16±0.02min(-1), 4.54±0.32min, 60min for daidzin and 0.16±0.02min(-1), 2.28±0.11min, 60min for genistin, respectively. The total aglycone content in black soymilk was enriched by 67.14±0.60% in the enzymatic treatment of 60min duration.
Article
The effect of heat treatment at 95-100 °C for 5 min and homogenization on the physicochemical properties of soymilk was studied, determining the particle size distribution and the amount and type of protein present after step-wise centrifugation. Differential scanning calorimetry of soy protein showed three thermal transitions for unheated soymilk at 54, 70 and 94 °C, which were attributed to 2S, 7S and 11S, respectively. These thermal transitions were absent from heated (and homogenized) soymilk. Unheated soymilk showed a large average particle size, a broad size distribution, and significant protein precipitation with centrifugation. Heating of soymilk decreased the particle size distribution and improved its stability. Homogenization also resulted in a decrease in particle size, with a narrower size distribution compared to heated soymilk. During step-wise centrifugation changes in the ratios of 11S (glycinin) and 7S (β-conglycinin) in the supernatants were noted, and they depended on the treatments applied to soymilk. Transmission electron microscopy observations showed the distribution of the colloidal particles in soymilk and helped further identify the differences after heating and heating with homogenization.
Article
Anthocyanins are naturally occurring polyphenolic pigments in plants that have been shown to decrease weight gain and insulin resistance in mice-fed high-fat diets. We investigated the effects of anthocyanins on cell growth, differentiation, and lipolysis in 3T3-L1 cells to test our hypothesis that anthocyanins could reduce adipose tissue mass by acting directly on adipocytes. Anthocyanin extracts from black soybeans were used and composed of 3 of the following major anthocyanins: cyanidine-3-O-glucoside (68.3%), delphinidin-3-O-glucoside (25.2%), and petunidin-3-O-glucoside (6.5%). Treatment with 12.5 and 50 μg/mL of black soybean anthocyanins exhibited inhibitory effects on the proliferation of both preconfluent preadipocytes (P < .01) and maturing postconfluent adipocytes (P < .01). In fully differentiated adipocytes, the number of viable cells was reduced by black soybean anthocyanins (P < .01). Treatment with 50 μg/mL of black soybean anthocyanins slightly increased epinephrine-induced lipolysis but decreased the basal lipolysis of fully differentiated adipocytes (P < .05). Black soybean anthocyanins also reduced lipid accumulation and suppressed the expression of the peroxisome proliferator-activated receptor γ, a major transcription factor for the adipogenic gene (P < .01). These results suggest that black soybean anthocyanins inhibit adipocyte differentiation and basal lipolysis, which may contribute to their antiobesity and antidiabetic properties.
Article
7S globulin was isolated according to a new method from soybeans. Its physicochemical properties were studied by differential scanning calorimetry (DSC) and by dynamic viscoelastic measurements. Heating DSC curves for 7S globulin showed only one endothermic peak. Extrapolation of the incipient temperature (T(i)) and the endothermic peak temperature (T(p)) observed at slow heating rates in DSC curves to 0-degrees-C/min led to the result T(i0) = 64-degrees-C and T(p0) = 70-degrees-C. The gelation process of 7S globulin solution was examined by dynamic rheological measurements at isothermal conditions. The storage modulus G' did not rise at temperatures below T(i0) (64-degrees-C) even after 120 min. The gelation time became shorter and the rate constant of gelation increased with increasing heating temperature. The storage modulus G' of 7S globulin gels heated for 120 min as a function of heating temperature increased up to T(p0) (70-degrees-C) and then decreased. These results indicated that the rheological behavior of 7S globulin gel was closely related to DSC curves and strongly influenced by the heating temperature.
Article
The effect of three different soaking treatments (6 hr in 50°C water; 6 hr in 50°C 0.25% NaHCO3 solution; or 30 min in boiling 0.25% NaHCO3 solution) was studied on the production of the major isoflavone aglucones, daidzein and genistein, and headspace volatile organic compounds including aldehydes, alcohols and furans in soybeans. Both 50° treatments resulted in production of substantial amounts of isoflavone aglucones and headspace volatile organic compounds. The boiling NAHCO3 treatment inhibited production of isoflavone aglucones and lowered total headspace volatile organic compounds.
Article
The conversion and degradation of isoflavones during dry or moist heating at 100, 150 and 200 °C, for varied lengths of time, were kinetically studied. Results showed that, at the early stage, all the reaction rates of malonylgenistin (MG), acetylgenistin (AG), genistin (G), and genistein (Ge) increased with increasing temperature and fitted a first-order model, when the concentration changes during heating were analyzed using HPLC. For dry heating, the conversion of MG to G exhibited the highest rate constant (h−1), followed by MG to AG, AG to G, AG to Ge, G to Ge and MG to Ge. Moist heating showed the same phenomenon; however, the last three conversions were not observed. In addition, MG had the highest degradation rate, followed by G, Ge and AG during dry heating, while the reversed trend occurred for moist heating. Moist heating was more susceptible to conversion and degradation of isoflavones than dry heating. The correlation coefficients (r2) ranged from 0.664 to 0.987 for moist heating and 0.688–0.960 for dry heating. The kinetic model developed in this study can be used to predict the concentration changes of isoflavones during dry heating and moist heating.
Article
Soy isoflavones are phenolic compounds comprised of aglucones, β-glucosides and β-glucosides conjugated with malonyl and acetyl groups. The β-glucosidases are a heterogeneous group of enzymes which hydrolyse β-glucosidic links of oligosaccharides and other glucosides conjugates releasing glucose. Thus the objective of this study was to determine the isoflavone forms content, β-glucosidase activity and their correlation in 18 soybean cultivars of different maturity groups under the same cultivation conditions. The predominant isoflavone forms were malonyldaidzin and malonylgenistin in all cultivars, corresponding to 67.0%, while β-glucoside and aglucone forms corresponded to 31.0% and 2.0%, respectively, of the total isoflavones; the acetylated form was not detected. This proportion among different forms was similar to all soybean cultivars studied. Regression analysis between number of days of maturity and all isoflavone forms were not significant. The relationship between maturity days and β-glucosides and malonyl-glucosides showed no correlation. However, a correlation was observed between maturity days and aglucones (P<0.08). Regression analysis and correlation between β-glucosidase activity and cultivars of different number of days of maturity were not significant, and β-glucosidase activity did not correlate with isoflavone forms contents (P<0.05).
Article
An optimal condition of supercritical fluid extraction (SFE) for isoflavone aglycones (daidzein and genistein) in soybean hypocotyls previously subjected to thermohydration at pH 5.0 and a temperature of 50 °C for 6, 12 and 18 h was developed. Different temperatures, pressures and cosolvents (methanol, ethanol, and acetonitrile) was tested and compared with solid–liquid extraction using aqueous methanol solution (80% v v−1) conducted in parallel for comparison. The extraction conditions were 50–70 °C, 176–380 bar, adding 0, 5, 10 mol% of cosolvents 80% in water as a modifier. The results from SC–CO2 showed that the cosolvent and pressure have significant effects in the extraction efficiency. It was found that the extraction conditions promoting the highest extraction of daidzein and genistein were at the temperature of 60 °C, pressure of 380 bar and both static and dynamic extraction of 15 min with the addition of 10% acetonitrile (80% v v−1). The maximum amounts of daidzein and genistein extracted by each method were solid–liquid extraction (70.07 mg 100 g−1) and carbon dioxide–acetonitrile (17.97 mg 100 g−1). The yield of daidzein and genistein achieved by a 30 min SC–CO2 extraction on soybean hypocotyls after 12 h soaking time was markedly improved by the addition of a modifier (acetonitrile) to the CO2 fluid. HPLC analysis of the obtained extracts revealed that extraction of isoflavone aglycones by SC–CO2 was 4.78 and 13.19 mg 100 g−1 for daidzein and genistein, respectively. The contents of daidzein and genistein obtained in the solid–liquid extraction were superior to 86% and 63%, respectively, compared to supercritical extraction.
Article
Eight strains of Lactobacillus plantarum, 6 strains of Lactobacillus casei, Lactobacillus acidophilus LA-5, and Bifidobacterium lactis BB-12 were screened for β-glucosidase activity. We then proceeded to investigate the enzymatic potential of selected strains for bioconversion of delphinidin and malvidin glycosides to their metabolites. L. plantarum and L. casei strains showed the highest cell-envelope associated β-glucosidase activity. Intracellular β-glucosidase activity from B. lactis BB-12 was up to 287-fold higher than that of the other strains. The L. acidophilus strain showed low β-glucosidase activity, both, intra and extracellularly. No aglycons were detected in bacterial extract reactions with anthocyanin glycosides. Delphinidin-3-glucoside underwent chemical degradation to form mainly gallic acid, although delphinidin-3-glucoside degradation due to B. lactis BB-12 and enzymatic activity towards chemically-formed metabolites due to L. casei LC-01 were observed. Incubation of malvidin-3-glucoside with B. lactis BB-12, L. plantarum IFPL722, and L. casei LC-01 cell-free extracts led to different patterns of gallic, homogentisic and syringic acid formation.
Article
The objectives of this study were to determine the phenolic and anthocyanin contents in black soybean Mallika and Cikuray variety seed coat extract and to examine antioxidant activity of extract against DPPH radical and LDL oxidation. Black soybean seed coat of Mallika (M) and Cikuray (C) was extracted using methanol-1%HCl. The phenolic and anthocyanin contents were determined with Folin–Ciocalteu and pH differential methods, respectively. Individual anthocyanidins were identified with HPLCdiode array detector, and antioxidant activity was examined, using DPPH and TBARS assay with LDL as the oxidation substrate. BHT and rutin were used as antioxidant references. The phenolic content in M and C were 8.15 ± 0.23 and 6.46 ± 0.11 g GAE/100 g, respectively. The anthocyanin contents were 11.36 ± 0.12 and 1.45 ± 0.13 g/100 g, respectively. Cyanidin, delphinidin, and pelargonidin were found as individual anthocyanidins. The optimum DPPH radical scavenging capacity (%) of M and C were 92.78% and 91.50%, respectively, BHT and rutin were 77.0% and 91.94%, respectively. The optimum inhibition of TBARS formation from M and C were 37.10 and 30.37 nmol MDA equivalents/g LDL protein, respectively, and rutin were 30.10 nmol MDA equivalents/g LDL protein, respectively. These results suggest that black soybean seed coat has high levels of phenolic and anthocyanin, and also demonstrated considerable antioxidant activity of black soybean seed coat.
Article
In order to study the content and composition of isoflavones retained in soybean seed component, obtained each component part the embryo, cotyledon and seed coat tissues of nine different soybean varieties were analyzed for 12 isoflavones using high performance liquid chromatography with photo diode array detector (HPLC-PDA) and were compared to each other. A total average concentration of isoflavone was 2887 μg g−1 in embryo, 575 μg g−1 in whole seed, 325 μg g−1 in cotyledon, and 33 μg g−1 in seed coat. With respect to each tissue of soybean varieties, isoflavone content was highest in Geomjeongkong 2 embryo (5701 μg g−1), Geomjeongolkong whole seed (1321 μg g−1), Heugcheongkong cotyledon (951 μg g−1), and Keunolkong seed coat (56 μg g−1). Isoflavone was least present in Keunolkong embryo (341 μg g−1), Hwaeomputkong whole seed (175 μg g−1), Seonheukkong cotyledon (81 μg g−1), and Seoklyangputkong seed coat (5 μg g−1). Overall, embryo and seed coat of all nine varieties contained isoflavones at the highest and lowest level, respectively. Isoflavones accumulated in the order of malonylglycoside, glycoside, acetylglycoside, and aglycon, among which malonylglycoside was the most abundant form ranging from 66% to 79% of the total isoflavone content in all three tissues. The embryo of cooked-with-rice soybean with black seed coat appears to be the best source of isoflavone.
Article
The recombinant β-glucosidase from the hyperthermophilic archaeon Pyrococcus furiosus was purified with a specific activity of 330 U/mg for genistin by His-trap chromatography. The specific activity of the purified enzyme followed the order genistin > daidzin > glycitin> malonyl glycitin > malonyl daidzin > malonyl genistin. The hydrolytic activity for genistin was highest at pH 6.0 and 95 °C with a half-life of 59 h, a K(m) of 0.5 mM, and a k(cat) of 6050 1/s. The enzyme completely hydrolyzed 1.0 mM genistin, daidzin, and glycitin within 100, 140, and 180 min, respectively. The soybean flour extract at 7.5% (w/v) contained 1.0 mM genistin, 0.9 mM daidzin, and 0.3 mM glycitin. Genistin, daidzin, and glycitin in the soybean flour extract were completely hydrolyzed after 60, 75, and 120 min, respectively. Of the reported β-glucosidases, P. furiosusβ-glucosidase exhibited the highest thermostability, k(cat), k(cat)/K(m), yield, and productivity for hydrolyzing genistin. These results suggest that this enzyme may be useful for the industrial hydrolysis of isoflavone glycosides.
Article
Concerns regarding the risk of estrogen replacement have resulted in a significant increase in the use of soy products by menopausal women who, despite the lack of evidence of the efficacy of such products, seek alternatives to menopausal hormone therapy. Our goal was to determine the efficacy of soy isoflavone tablets in preventing bone loss and menopausal symptoms. The study design was a single-center, randomized, placebo-controlled, double-blind clinical trial conducted from July 1, 2004, through March 31, 2009. Women aged 45 to 60 years within 5 years of menopause and with a bone mineral density T score of -2.0 or higher in the lumbar spine or total hip were randomly assigned, in equal proportions, to receive daily soy isoflavone tablets, 200 mg, or placebo. The primary outcome was changes in bone mineral density in the lumbar spine, total hip, and femoral neck at the 2-year follow-up. Secondary outcomes included changes in menopausal symptoms, vaginal cytologic characteristics, N -telopeptide of type I bone collagen, lipids, and thyroid function. After 2 years, no significant differences were found between the participants receiving soy tablets (n = 122) and those receiving placebo (n = 126) regarding changes in bone mineral density in the spine (-2.0% and -2.3%, respectively), the total hip (-1.2% and -1.4%, respectively), or the femoral neck (-2.2% and -2.1%, respectively). A significantly larger proportion of participants in the soy group experienced hot flashes and constipation compared with the control group. No significant differences were found between groups in other outcomes. In this population, the daily administration of tablets containing 200 mg of soy isoflavones for 2 years did not prevent bone loss or menopausal symptoms. clinicaltrials.gov Identifier: NCT00076050.
Article
The seed coats of black soybean (Glycine max (L.) Merr.) accumulate red (cyanidin-), blue (delphinidin-), purple (petunidin-), and orange (pelargonidin-based) anthocyanins almost exclusively as 3-O-glucosides; however, the responsible enzyme has not been identified. In this study, the full-length cDNA which encodes the enzyme that catalyzes the final step in anthocyanin biosynthesis, namely UDP-glucose:flavonoid 3-O-glucosyltransferase (UGT78K1), was isolated from the seed coat tissue of black soybean using rapid amplification of cDNA ends (RACE). Of the 28 flavonoid substrates tested, the purified recombinant protein glucosylated only anthocyanidins and flavonols, and demonstrated strict 3-OH regiospecificity. Galactose could also be transferred with relatively low activity to the 3-position of cyanidin or delphinidin in vitro. These findings are consistent with previous reports of mainly 3-O-glucosylated and minor amounts of 3-O-galactosylated anthocyanins in the seed coat of black soybean. The recombinant enzyme exhibited pronounced substrate inhibition by cyanidin at 100 microM acceptor concentration. Transfer of UGT78K1 into the Arabidopsis T-DNA mutant (ugt78d2) deficient in anthocyanidin and flavonol 3-O-glucosyltransferase activity, restored the accumulation of anthocyanins and flavonols, suggesting the in vivo function of the enzyme as a flavonoid 3-O-glucosyltransferase. Genomic and phylogenetic analyses suggest the existence of three additional soybean sequences with high similarity to UGT78K1. RT-PCR confirmed the co-expression of one of these genes (Glyma08g07130) with UGT78K1 in the seed coat of black soybean, suggesting possible functional redundancies in anthocyanin biosynthesis in this tissue.
Article
There are limited reports on the bioavailability and pharmacokinetics of isoflavones in elderly humans and aged animals. The present study was conducted to assess the effect of glycosidation of isoflavones on their bioavailability and pharmacokinetics in aged (20 month old) male Fischer-344 (F-344) rats. The F-344 rat, developed by the National Institute on Aging, is an inbred rat model that is commonly used for aging studies and resembles many features of aging humans. Three sources of isoflavones; Novasoy (a commercial supplement), a mixture of synthetic aglycons (daidzein, genistein and glycitein), and a mixture of synthetic glucosides (daidzin, genistin, and glycitin) were tested. Following administration, blood samples were collected at different times (0-48 h post-oral gavage and 0-8 h post-IV dosing). Plasma isoflavones and 7-hydroxy-3-(4'-hydroxyphenyl)-chroman (a metabolite of daidzein) were measured by LC/MS. The extent of absorption was determined by comparing the area under the curve (AUC) of the plasma-concentration time curve after intravenous (IV) administration with that following oral administration. The extent of bioavailability was then calculated as: %bioabailability = (AUC(or)/AUC(IV))x(Dose(IV)/Dose(or))x100. Bioavailabilities for genistein were significantly (p = 0.013) higher for the aglycon (35 +/- 9%) compared with the glucoside forms (11 +/- 3%). In contrast, the bioavailabilities for glycitein were significantly (p = 0.011) higher in Novasoy (27 +/- 13%) and the glucoside form (21 +/- 10%) compared with the aglycon (8 +/- 3%). No significant differences in the bioavailability of daidzein were observed in aged rats dosed with aglycon, glucoside or Novasoy. However, aged rats were able to produce equol as early as 8 h post-dosing. In summary, the source of isoflavones had significant effects on genistein and glycitein bioavailability in aged male rats.
Article
Attractive color is one of the most important sensory characteristics of fruit and berry products, and elderberry juice is widely used as natural colorant. When pectinase preparations were used in the production of elderberry juice for clarification, a concomitant decrease of anthocyanins and thus a color loss were observed. This paper demonstrates that this is due to side glycosidase activities contained in commercial pectinase preparations from Aspergillus sp. Using LC-MS, sequential deglycosylation of cyanidin-3-sambubioside, cy-3-glucoside, cy-3-sambubioside-5-glucoside, and cy-3,5-diglucoside was found to be catalyzed by specific glycosidases contained in the pectinase preparations. There was no big difference in the deglycosylation rate between monoglucosidic or diglucosidic anthocyanins. However, the degradation rate was decreased when rutinose was attached to cyanidin, whereas the structure of the aglycone itself had almost no influence. Pure beta-glucosidases from Agrobacterium species and Aspergillus niger and the beta-glucosidase N188 from A. niger did not show any conversion of anthocyanins, indicating the presence of specific glycosidases. Thus, an activity gel based assay was developed to detect anthocyanin-specific glycosidase activity in enzyme preparations, and according to LC-MS peptide mass mapping of digested bands, homologies to a beta-glucosidase from Aspergillus kawachii were found.
Article
Whey proteins were modified by reaction with selected phenolic compounds (ferulic-, chlorogenic-, caffeic- and gallic acid) and related substances (quinic acid and p-quinone) as well as with extracts from coffee, tea, potato and pear at pH 9. The derivatives formed were characterized in terms of their physicochemical and digestion properties. The derivatization was accompanied by a reaction at the lysine and tryptophan side chains, whereby their content was decreased in comparison to that in the control whey proteins. Moreover, the solubility of the derivatives decreased over a broad pH range and the derivatization influenced the hydrophobe-hydrophile character of the whey proteins. The isoelectric points were shifted to lower pH values in the order of reactivity as follows: gallic acid > p-quinone > caffeic acid > chlorogenic acid. The other derivatives showed no or few changes compared to the control whey proteins. The formation of high molecular fractions was documented with SDS-PAGE. Especially the derivatives of chlorogenic-, caffeic-, gallic acid and p-quinone showed an increase in molecular weight of beta-lactoglobulin fraction from 18,300 to 20,000 Da. A dimer formation in molecular range 40,000 was also registered. MALDI-TOF-MS was applied to characterize the binding of the individual phenolic compounds or their oxidation products to the whey protein fractions, alpha-lactalbumin and beta-lactoglobulin. In vitro experiments showed that the digestion of the derivatized whey proteins with the enzymes of the gastrointestinal tract (trypsin, chymotrypsin, pepsin and pancreatin) was adversely effected. Similar results with regard to physicochemical characterization and digestion properties of the whey proteins treated with the applied extracts from plant beverages, fruit and vegetable were also documented. Coffee and tee were comparatively the most reactive extracts.
Article
Anthocyanins are suggested to be responsible for protective effects against cardiovascular diseases and certain forms of cancer. Although previous studies have implicated that intact anthocyanidin glycosides were decreased extensively by interactions in the gastrointestinal tract, only few data are available concerning the metabolism by the intestinal microflora. Using a new in vitro model, we have investigated the microbial deglycosylation and degradation of six anthocyanins exhibiting three different aglycones with mono- or di-beta-D-glycosidic bonds using high-performance liquid chromatography-diode array (HPLC-DAD) and gas chromatography-mass spectrometry (GC-MS) detection. We have found that all anthocyanidin glycosides were hydrolysed by the microflora within 20 min and 2 h of incubation depending on the sugar moiety. Due to the high instability of the liberated aglycones at neutral pH, primary phenolic degradation products were already detected after 20 min of incubation. Further metabolism of the phenolic acids was accompanied by demethylation. Because of their higher chemical and microbial stability, phenolic acids and/or other, not yet identified, anthocyanin metabolites might be mainly responsible for the observed antioxidant activities and other physiological effects in vivo.
Article
Anthocyanin pigments from a wide variety of edible and ornamental black, blue, pink, purple, red, and white wheat, barley, corn, rice, and wild rice were identified and quantified to evaluate their potential as natural colorants or functional food ingredients. The total anthocyanin contents varied significantly and exhibited a range of 7-3276 microg/g. Some grains, such as red rice and black rice, contained a limited number of pigments, whereas others, such as blue, pink, purple, and red corns, had complex anthocyanin profiles. Of the 42 anthocyanin compounds observed, 9 were characterized by comparison of the spectroscopic and chromatographic properties with those of authentic standards. The remaining compounds were tentatively identified on the basis of spectroscopic properties and electrospray ionization mass spectra. The most abundant anthocyanins were cyanidin 3-glucoside in black and red rices and in blue, purple, and red corns, pelargonidin 3-glucoside in pink corn, and delphinidin 3-glucoside in blue wheat.
Article
The objective of this study was to investigate how 6 commonly used solvent systems affected the yields of phenolic substances and the antioxidant capacity of extracts from 8 major classes of food legumes. Several antioxidant-related phytochemical compositions, namely, total phenolic content (TPC), total flavonoids content (TFC), and condensed tannins content (CTC), were investigated. In addition, antioxidant activities were tested using 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging, ferric-reducing antioxidant power (FRAP), and the oxygen radical absorbance capacity (ORAC). The results showed that the 50% acetone extracts exhibited the highest TPC for yellow pea, green pea, chickpea, and yellow soybean. Acidic 70% acetone (+0.5% acetic acid) extracts exhibited the highest TPC, TFC, and FRAP values for black bean, lentil, black soybean, and red kidney bean. The 80% acetone extracts exhibited the highest TFC, CTC, and DPPH-free radical scavenging activity for yellow pea, green pea, chickpea, and yellow soybean. The 70% ethanol extracts exhibited the greatest ORAC value for all selected legumes. These results indicated that solvents with different polarity had significant effects on total phenolic contents, extracted components, and antioxidant activities. High correlations between phenolic compositions and antioxidant activities of legume extracts were observed. The information is of interest to the nutraceutical food/ingredient industries since legumes are a rich source of antioxidants.