Buckwheat Extracts Research Articles

Determination ofd-chiro-Inositol in Tartary Buckwheat Using High-Performance Liquid Chromatography with an Evaporative Light-Scattering Detector

A simple method for rapid determination of d- chiro-inositol (DCI) (a potent mediator of insulin metabolism) contained in tartary buckwheat ( Fagopyrum tataricum L. Gaench) was developed on the basis of high-performance liquid chromatography coupled to an evaporative light scattering detector (ELSD). DCI was separated from an extract of tartary buckwheat on an Alltech Prevail Carbohydrates ES 5 mum column. During postcolumn detection, DCI was detected by ELSD. The detection limit was 100 ng. This method was sensitive enough for determining DCI in tartary buckwheat and its related products.

Application of the 16-kDa buckwheat 2 S storage albumin protein for diagnosis of clinical reactivity

The 16-kDa protein of buckwheat (BW) has been implicated as a major allergen in BW allergy. To characterize the 16-kDa allergen and evaluate its clinical significance as an indicator of BW allergy. Complementary DNA from the 16-kDa allergen was cloned and expressed in Escherichia coli. Allergenicity was confirmed with IgE immunoblotting or with an enzyme-linked immunosorbent assay. The clinical utility of the recombinant protein (r16 kDa) for diagnosis of BW reactivity was evaluated in 18 BW-allergic and in 20 asymptomatic BW-sensitized subjects. The 16-kDa allergen, composed of 127 amino acids, has 50% homology to the reported 8-kDa BW allergen, which belongs to the 2 S storage albumin. The r16-kDa protein can inhibit specific IgE (sIgE) antibody binding to the native BW 16-kDa allergen but minimally inhibited sIgE binding to crude BW extract. Approximately 77.8% of patients with the BW allergy produced sIgE antibodies to the r16-kDa protein, compared with a complete lack of reactivity in the 20 asymptomatic BW-sensitized subjects. The areas of the receiver operating characteristic curves for the skin prick test (mean, 0.93; 95% confidence interval, 0.85 to approximately 1.01; P < .001) and the rl6-kDa enzyme-linked immunosorbent assay (mean, 0.93; 95% confidence interval, 0.84 to approximately 1.01; P < .001) were higher than the area of the BW IgE measurement curve determined by ImmunoCAP (a system for assaying serum IgE) (mean, 0.80; 95% confidence interval, 0.66 to approximately 0.94; P = .002). The 16-kDa allergen belongs to the 2 S storage albumin. Measurement of rl6-kDa sIgE was more discriminating than measurement of ImmunoCAP sIgE in whole BW extracts for the diagnosis of clinical reactivity to BW.

Characterization of Buckwheat 19-kD Allergen and Its Application for Diagnosing Clinical Reactivity

Background: The 19-kD protein of buckwheat (BW) has been suggested to be a major allergen, but its characteristics and clinical significance are poorly defined. Methods: cDNA of the 19-kD BW allergen was cloned and expressed in Escherichia coli. Allergenicity and cross-allergenicity were confirmed by inhibition immunoblotting or by ELISA inhibition. The recombinant (r19-kD) protein was assessed for clinical utility in the diagnosis of BW reactivity in 18 BW-allergic and 19 BW-asymptomatic sensitized subjects using receiver operating characteristic analysis. Results: The 19-kD BW allergen, which is composed of 135 amino acids, has a weak homology to the vicilin-like allergens of cashew (Ana o 1), English walnut (Jug r 2) and 7 S globulin from Sesamum indicum. The r19-kD protein can inhibit sIgE binding to native 19-kD BW allergen. The maximum percentage inhibition of sIgE binding to crude BW extract was 56%. About 83.3% of the BW allergy patients had sIgE bound to r19-kD protein, compared to only 1 of the 19 BW-asymptomatic sensitized subjects. The areas under the receiver operating characteristic curves for the skin prick tests [0.925 (95% confidence interval: 0.839–1.012), p < 0.001] as well as r19-kD protein sIgE ELISAs [0.860 (95% confidence interval: 0.725–0.995), p <0.001] were higher than that of BW sIgE coated allergen particle test results [0.803 (95% confidence interval: 0.661–0.945), p = 0.002]. Conclusions: The 19-kD BW allergen may be the major allergen from BW. For the diagnosis of clinical reactivity to BW, the r19-kD protein sIgE ELISA test was more discriminative than the coated allergen particle sIgE measurement using whole BW extract.

Comparison of Spectrophotometric and Electrochemical Methods for the Evaluation of the Antioxidant Capacity of Buckwheat Products after Hydrothermal Treatment

This paper reports the use of spectrophotometric and voltammetric methods for the determination of the antioxidant capacity of buckwheat and its products originated from a technological line of a buckwheat roasted groats producer. 80% methanol extracts from raw and roasted buckwheat and groats and hulls obtained from roasted buckwheat were used. The spectrophotometric methods included (1) free radical scavenging activities of the extracts against ABTS*+ radical cation (TEAC) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH RSA) and (2) determination of reducing capacity by the means of Folin-Ciocalteu reagent (FCR) application. The radical scavenging activities of the extracts were also investigated using a voltammetric assay. Moreover, the flavonoids profiles of the studied materials were provided. Buckwheat roasting caused a decrease in TEAC, DPPH RSA, and FCR reducing capacity by 70%. The lowest TEAC, DPPH RSA, and FCR reducing capacities were noted for roasted groats. Both DPPH RSA and TEAC methods were highly positively correlated with the FCR reducing capacity assay (r = 0.98 and r = 0.99). Cyclic voltammograms of analyzed buckwheat extracts were useful for evaluation of the antioxidant capacity. The total charge below the anodic current waveform was correlated with the data obtained by TEAC (r = 0.770), DPPH RSA (r = 0.88), and FCR reducing capacity (r = 0.81). The changes in the antioxidant capacity of buckwheat and its products followed the changes in flavonoids composition. In particular, the concentration of flavonoids was related to measurements by cyclic voltammetry.

Anaphylaxis Due To Buckwheat Skin Testing

INTRODUCTION: Buckwheat is a common crop in Asia, Europe and USA. Like peanut, buckwheat allergy can be fatal. To our knowledge, while anaphylaxis after skin testing with nuts is not exceptional, there has been no report of such with buckwheat. We report herein the first case. CASE HISTORY: A 26 year-old Chinese female presented to the Emergency Department with pruritic wheals, dyspnoea and hoarseness 15 minutes after eating Japanese buckwheat noodles. On examination, she had a swollen uvula, periorbital swelling, and generalised urticaria. Prompt recovery followed epinephrine, steroids and antihistamine administration. A referral to our service was made. She reported 2 previous episodes of similar reactions. Once after eating a sandwich containing olives, another after a muesli bar with avocadoes. Both were likely to have contained buckwheat. Skin prick tests (Greers) to peanuts, tree nuts, fish, shrimps, crabs, mussels, clams, scallops, oyster, milk, soy, and wheat were negative. On another occasion, skin prick tests to commercial buckwheat allergen (ALK); and prick-by-prick with raw and cooked buckwheat extract, olives and avocadoes were performed. All the buckwheat tests resulted in positive reactions with the largest wheal being 14mm x 9mm. During this session, she developed anaphylaxis evidenced by flushing and dyspnoea. Peak expiratory flow rates improved from 300 to 370 after epinephrine, antihistamine and steroid administration. Subsequent open-food challenges to avocadoes and olives were negative, confirming buckwheat as the allergen causing anaphylaxis after skin testing. CONCLUSION: In patients at risk of anaphylaxis, it is advisable to use only diluted commercial buckwheat extract for skin testing with resuscitative equipment readily available.

Identification of plants with potential anti-diabetic effects by using a screening platform to recognize partial PPARγ agonists

Worldwide more than 160 million people suffer from type 2 diabetes (T2D) which signifies that it has reached almost epidemic proportions. T2D is characterized by insulin resistance and the recommended treatment is a change in lifestyle often supplemented by insulin sensitizing drugs. These drugs bind to and activate the Peroxisome Proliferator-Activated Receptor (PPAR) γ, a key regulator of adipogenesis. However, side-effects do occur due to the fact that the drugs are full PPARγ agonists. Hence, partial PPARγ agonists are sought for as evidence suggests these to have less side-effects. Plants have traditionally been used in the treatment of diabetes, making them a potential source of natural products with anti-diabetic effects. A number of plants were selected for testing in a screening platform that makes identification of partial PPARγ agonsits possible. The platform consists of several bioassays which test for PPARγ activation, followed by tests for adipocyte differentiation, glucose uptake, and PPARα and δ activation. Extracts/compounds tested in this row of bioassays will only proceed through by passing each step satisfactory. Partial PPARγ agonists identified in the platform will then be subjected to animal and clinical testing. In the end, this process as a whole can lead to the identification of potential PPARγ activators without the side-effects seen for drugs used in T2D treatment today. Plant material from 23 plants was sequentially extracted with hexane, followed by CH2Cl2, CH3OH and finally H2O. More than 60% of the tested plants were found to contain partial PPARγ agonists. The most promising anti-diabetic effects were observed in extracts of purple coneflower (hexane), winter savoury (hexane, CH2Cl2), elderflower (CH2Cl2, MeOH), sage (hexane, CH2Cl2), and buckwheat (hexane, CH2Cl2). By the use of bioassay-guided chromatographic fractionation it will then be possible to isolate and identify the active principles from the plant extracts.

Analysis of element species fractions in buckwheat and amaranth flours by SEC/ICP-MS and MALDI-MS

Fractionation of Co, Cu, Fe, Mn, Mo, Ni, P and Zn in extracts of buckwheat and amaranth flour in 0.02 mol·l−1 Tris-HCl (pH = 7.5) buffer was performed by SEC/ICP-MS. All metals except for Fe and Mn (both samples) and Cu (amaranth only) are concentrated in a low-molecular fraction (M r < 2 kDa). Fe is bound in a high-molecular fraction (M r > 150 kDa). The main part of Mn is present as a labile complex or an ionic form. Cu in amaranth extract is also bound in medium-molecular fractions (10 and 40 kDa) and in a high-molecular one (M r > 150 kDa). Fractions rich in trace metals were isolated using preparative-scale SEC and the organic ligands of metals were refined by immobilized metal affinity chromatography. Low content of sulphur-containing amino acids (Cys, Met) and high content of acidic amino acids (Glu, Asp) are typical for all these purified fractions. A part of Zn (buckwheat) and almost all Cu (amaranth) in the low-molecular fractions were located in phosphorus rich sub-fractions. However, all Ni (both samples), the majority of Zn (buckwheat) and all Cu (buckwheat) were found in phosphorus-less sub-fractions. No phytochelatins were found in MALDI-MS spectra of isolated ligands.

A CE Method for Measuring Phototoxicity in Vitro

This paper presents an experimental setup which employs capillary electrophoresis with electrochemical and UV detection to test phototoxicity of plant extracts and components in terms of oxygen consumption and generation of reactive oxygen species upon irradiation with visible light. The experimental setup was used to test the phototoxicity of different buckwheat extracts and individual plant derived substances. The buckwheat extracts showed differences in their phototoxic behavior which might be due to different phytochemical composition. Screening of individual components revealed that rutin and quercetin alone were not phototoxic, but quercetin in combination with hypericin and chlorophyll caused considerable oxygen consumption. It has been demonstrated that the apparatus is a valuable tool to screen in vitro potential phototoxic reactions of plant extracts and individual constituents.

Differential Effects of Buckwheat and Kudingcha Extract on Neuronal Damage in Cultured Hippocampal Neurons and Spatial Memory Impairment Induced by Scopolamine in an Eight-Arm Radial Maze

We have reported the neuroprotection provided by an extract of buckwheat (BWE, Fagopyrum esculentum Moench) on neuronal damage in the repeated cerebral ischemia model and demonstrated that BWE inhibited the excess glutamate release induced by repeated cerebral ischemia, suggesting that BWE had a free radical-scavenging in addition to anti-glutamate action. In the present study, we studied the neuroprotective effects of Kudingcha extract (KDE, Ligustrum purpurascens Y. C.) on scavenging by the 2,2-diphenyl-1-picylhydrazyl (DPPH) radical in primary cultured hippocampal neurons, and on spatial memory impairment induced by scopolamine in an eight-arm radial maze in comparison with BWE. The effects of KDE (0.01-1 mg/ml) were more potent than those of BWE (0.01-1 mg/ml) in scavenging the DPPH radical (1 mM). KDE (100 μg/ml) prevented the cell damage induced by glutamate (300 μM) or kainate (1 mM), which was more potent than BWE (100 μg/ml), but BWE suppressed the cellular damage induced by β-amyloid(25-35) (20 μM) more potently than KDE (100 μg/ml). BWE (600 mg/kg), but not KDE, significantly suppressed the increase in errors induced by scopolamine (0.5 mg/kg i.p.) in the eight-arm radial maze. The results suggest that BWE may protect against cholinergic dysfunction and that KDE protects more effectively against glutaminergic dysfunction.

Antioxidant activities of buckwheat extracts

The antioxidant activities of buckwheat ( Fagopyrum esculentum Möench) extracts were evaluated and compared with butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT) and tertiary butylhydroquinone (TBHQ) using a β-carotene bleaching assay, a 2,2-diphenyl-β-picrylhydrazyl (DPPH) assay and the Rancimat method. Buckwheat was extracted with solvents of different polarities. The methanol extract showed the highest antioxidant activity coefficient (AAC) of 627 ± 40.0 at 200 mg/l by the β-carotene bleaching method and longest induction time of 7.0 ± 0.2 h by the Rancimat method. The acetone extract showed the highest total phenolics of 3.4 ± 0.1 g catechin equivalents/100 g and the highest scavenging activity of 78.6 ± 6.2% at 0.1 mg/ml by the DPPH method. The properties of the extracting solvents significantly affected the yield, total phenolics and antioxidant activity of buckwheat extract.

Development and Application of a CE Method for Quantification of Phenolic Compounds in Extracts from Buckwheat Herb and in Semi-Solid Formulations Containing the Extracts

Because of the growing interest in plant-derived substances for medical and cosmetic applications, appropriate analytical methods must be developed to ensure the quality of herbal extracts. This paper describes a CE method for the quantification of phenolic compounds in extracts from buckwheat herb. The optimum analytical conditions (60 mM borate buffer, pH 10.0, injection time 10 s) were obtained by variation of injection time, the pH and molarity of the running buffer. Comparison with a previously developed HPLC method showed that the new CE method is comparable in terms of precision, linearity, and limit of detection. It is also much faster and less expensive than the HPLC method. Application of the CE method to different extracts showed that the extracts are rather stable to high temperature but very sensitive to high humidity. It is demonstrated that the CE method is also suitable for determination of rutin in buckwheat extracts incorporated into two different semi-solid formulations.

Molecular characterization of a 10‐kDa buckwheat molecule reactive to allergic patients’ IgE

Using the sera from buckwheat (BW)-allergic patients, several putative causative molecules were reported. However, few molecules were determined on the molecular structure. We demonstrated in 2000 that the major allergen with 24 kDa (BW24KD) is a legumin-like storage protein. The aim of this study was to isolate and characterize further a major allergen with 10 kDa by molecular cloning. Buckwheat allergens were identified by immunoblotting analysis using sera from 14 allergic and two nonallergic individuals. We identified a protein with 10 kDa (BW10KD) that reacted with immunoglobulin E (IgE) more strongly than with IgG and IgA in 57% of the allergic patients but not with IgE in nonallergic individuals. Analyses were performed by N-terminal amino acid sequencing and molecular cloning. Physiological significance was assessed by an immunoblotting experiment showing that the reactivity of an allergic patient's serum IgE to BW10KD was competitively inhibited by natural BW extracts. Molecular cloning experiments indicated that BW10KD as a BW allergen was a member of the 2S-albumin multigene family.

Cross-reactivity from poppy seed to buckwheat in a food allergic patient with poppy seed anaphylaxis

Rationale The opium poppy, Papaver somniferum L., is the source of both poppy seeds and opium. The commercially available seeds are widely used as ingredients for various kinds of food. IgE-mediated sensitization to poppy seeds is rare but if present, clinical symptoms are usually severe. Cross-reactivity between poppy seeds and other food allergens have been described with sesame, hazelnut, rye grain and kiwi fruit. We report a novel cross-reactivity with buckwheat in a 17-year-old female with poppy seed anaphylaxis. Methods Skin prick test, CAP-FEIA, CAP-inhibition tests, immunoblotting, immunoblot-inhibition and open oral food challenge tests were performed. Results Prick tests with native poppy seeds were strongly positive. Total serum IgE was raised to 646 kU/l, and allergen specific IgE against poppy seed (287 kU/l), hazelnut, sesame, buckwheat, brasil nut, pistachio, cashew nut and almond was detected by CAP-FEIA. CAP inhibition tests demonstrated a cross-reactivity from poppy seed to buckwheat but not to natural rubber latex. Immunoblotting of poppy seed extracts with our patients serum revealed 4 distinct allergen bands, which were inhibited after preincubation with buckwheat extract. The immunoblot for opium latex or raw opium was negative. Oral food challenge with up to 10 g of unground poppy seeds were negative, whereas 1 g of ground poppy seeds led to urticaria, heat sensation, pruritus, conjunctivitis and dyspnoe followed by a threefold raise of mast cell tryptase in serum (5.4 to 17.6 μg/l) within 3 hours. Conclusions Buckwheat must be considered as a novel cross-reactive allergen in at least some poppy seed allergic patients.

Identification and determination of flavonoids in buckwheat (Fagopyrum esculentum Moench, Polygonaceae) by high-performance liquid chromatography with electrospray ionisation mass spectrometry and photodiode array ultraviolet detection.

An analytical method for flavonoids present in the seed extract of buckwheat (Fagopyrum esculentum Moench, Polygonaceae), using HPLC and a photodiode array detector and interfaced to an electrospray ionisation mass spectrometer, has been developed. Structural information about the flavonols was obtained from the retention time characteristics, the UV-visible spectra and the mass spectra without the need to isolate the individual compounds. The methanol extract of buckwheat contained principally four flavonol glycosides: rutin, quercetin, kaempferol-3-rutinoside and a trace quantity of a flavonol triglycoside.

Buckwheat extract inhibits progression of renal failure.

Rats subjected to partial resection of the parenchyma showed reduced radical-scavenging activity in the remaining kidney and increased severity of renal tissue lesions. However, in similarly nephrectomized rats given buckwheat extract, the state of oxidative stress improved by restoring the decreased activities of reactive oxygen species-scavenging enzymes such as superoxide dismutase and catalase. The degree of mesangial proliferation, severity of extratubular lesions such as crescents and adhesions, glomerulosclerosis index, and severity of tubular interstitial lesions also improved. In addition, nephrectomized rats given buckwheat extract showed improvement in renal function, as indicated by decreased serum level of creatinine, with a significant decrease in the level of methylguanidine, a uremic toxin produced from creatinine in the presence of hydroxyl radical.

Effects of buckwheat in a renal ischemia-reperfusion model.

Experiments were done to find whether buckwheat extract ameliorates the renal injury induced by ischemia-reperfusion. In ischemic-reperfused control rats, the activities of antioxidative enzymes in renal tissue and blood and renal parameters deviated from the normal range, indicating dysfunction of the kidneys. In contrast, when buckwheat extract was given orally for 20 consecutive days before ischemia and reperfusion, the activities of the antioxidation enzymes superoxide dismutase, catalase, and glutathione peroxidase were higher, while thiobarbituric acid-reactive substance levels in serum and renal tissue were lower in the treated rats than in the controls. Decreased levels of urea nitrogen and creatinine in serum demonstrated a protective effect against the renal dysfunction caused by ischemia and recirculation. On the other hand, it was demonstrated that buckwheat extract had a protective effect on cultured proximal tubule cells subjected to hypoxia-reoxygenation, probably by preventing oxygen free radicals from attacking the cell membranes.

Analysis of Anti-Prolamin Monoclonal Antibody Reactivity Using Prolamin Fractions Purified by Preparative Electrophoresis

Coeliac disease (CD) is a gastrointestinal afliction triggered by the ingestion of prolamins from wheat, barley, rye and possibly oats. The only treatment for CD is a strict diet, free of the toxic components. Immunochemical methods are usually applied to certify foods aimed at coeliac patients. The characterization of a panel of four anti-prolamin monoclonal antibodies (MAbs) to be used to certify gluten-free products is described here. To this aim, purified gliadin, secalin and hordein fractions were obtained by preparative electrophoresis at acid pH. This procedure provides purified fractions not exposed to denaturing conditions. The specificity of the MAbs was tested by ELISA against purified fractions and ethanol extracts of wheat, barley, rye, oats, rice, maize, buckwheat, sorghum and soy. The four MAbs recognized only coeliac-toxic cereals. Each MAb reacted strongly with gliadins and showed differential reactivity against the different prolamin purified fractions. Some MAbs showed a broad pattern of recognition whereas others presented a more restricted one. The reactivity observed corresponded to structural homologies among gliadin, secalin and hordein fractions. It is remarkable that some fractions obtained by electrophoresis in the presence of sodium dodecylsulphate were not recognized by some MAbs, whereas the same components obtained by preparative A-PAGE showed high reactivity. This reinforces the suitability of the purification method employed in this study to isolate prolamin fractions. Using these purified prolamins, characterization of anti-prolamin MAb reactivity was achieved.

Molecular characterization of buckwheat major immunoglobulin E-reactive proteins in allergic patients

Buckwheat extract was analyzed by immunoblotting experiments using sera from nine allergic and three non-allergic individuals. Major IgE-reactive bands were 73, 70, 62, 58 and 54 kDa under non-reducing conditions and were detected in allergic subjects, but not in non-allergic ones. Under reducing conditions, the 73, 70, 62 and 58 kDa bands split to 56 and 24, 52 and 24, 45 and 24, and 43 and 24 kDa, respectively. The 24 kDa molecule was the most prominent band recognized with IgE as well as IgG or IgA. The FA02 cDNA clone, encoding the α and β subunits of the legumin-like storage protein, was isolated from a cDNA library made of immature buckwheat seeds. The deduced amino acid sequence of the cDNA clone is substantially identical to the N-terminal amino acid sequence of the 24 kDa molecule, which may be identical to that of BW24KD reported by Urisu et al. Consistent with these results, the translation product of the cDNA encoding the putative β subunit was strongly recognized with serum IgE, IgG and IgA from buckwheat-allergic patients. These results suggested that the 24 kDa molecule may be the β subunit of the legumin-like storage molecule of buckwheat.

Antioxidant and radical‐scavenging activities of buckwheat seed components

AbstractThe search for endogenous components in food ingredients exhibiting antioxidant activity has been intensified in order to eliminate synthetic antioxidants. Tocopherols are widely used as natural antioxidants, although their protective ability is not always sufficient. Buckwheat seed components were evaluated for antioxidant and free radical‐scavenging activities using solvents of different polarities to isolate components from hulls and groats. Components extracted from buckwheat hulls were pro‐oxidant in canola oil. Antioxidant activity of extracts from buckwheat groats increased when more polar solvents were used for extraction. The highest activity was observed for the methanolic extract. Radical‐scavenging activity of buckwheat extracts was analyzed with DPPH (2,2‐diphenyl‐2‐picryl‐hydrazyl). This activity increased when the more polar solvents were used for extraction, with the highest activity observed for the methanolic extract. It was also observed that the radical scavenging effectiveness of extracts was concentration dependent. Analysis revealed the presence of tocopherols in the hexane extract, while methanolic extracts were rich in phenolic acids and flavonoids.

Catechins as Antioxidants from Buckwheat (Fagopyrum esculentum Moench) Groats

Four catechins and rutin were isolated from ethanol extracts of buckwheat (Fagopyrum esculentum Moench) groats by Sephadex LH-20 column chromatography and preparative HPLC with monitoring of the peroxyl radical scavenging activity. The antioxidant activity of these catechins was higher than that of rutin. The structures of these catechins were established as (−)-epicatechin, (+)-catechin 7-O-β-d-glucopyranoside, (−)-epicatechin 3-O-p-hydroxybenzoate, and (−)-epicatechin 3-O-(3,4-di-O-methyl)gallate on the basis of 1H, 13C, and two-dimensional nuclear magnetic resonance techniques and fast atom bombardment mass spectrometry. The yields of these antioxidant compounds suggest that they are abundant, as is rutin, which is known as a biological phytochemical in buckwheat groats. Keywords: Fagopyrum esculentum; antioxidant activity; flavonoids; (−)-epicatechin; (+)-catechin 7-O-β-d-glucopyranoside; (−)-epicatechin 3-O-p-hydroxybenzoate; (−)-epicatechin 3-O-(3,4-di-O-methyl)gallate