Trace element water improves the antioxidant activity of buckwheat (Fagopyrum esculentum Moench) sprouts

Buckwheat (Fagopyrum esculentum Moench) was grown in trace element water (TEW) (100, 200, 300, 400, and 500 ppm) and deionized water (DIW) to evaluate whether the beneficial effects of trace elements on the antioxidant activity could be accomplished with the supplement of TEW. At 300 ppm, TEW significantly increased the Cu, Zn, Mn, and Fe contents in buckwheat sprout but not the Se content. However, the levels of rutin, isoorientin, vitexin, and isovitexin did not differ between buckwheat sprouts grown in TEW and DIW. The ethanolic extract from buckwheat sprout grown in 300 ppm of TEW showed higher ferrous ion chelating activity and inhibitory activity toward lipid peroxidation than that grown in DIW. The extract in the TEW group also enhanced intracellular superoxide dismutase activity and lowered reactive oxygen species and superoxide anion in the human Hep G2 cell. It was concluded that TEW could increase the antioxidant activities of buckwheat sprouts.     

Tartary buckwheat (Fagopyrum tataricum Gaertn.) as a source of dietary rutin and quercitrin

Two samples of tartary buckwheat (Fagopyrum tataricum Gaertn.) from China and one from Luxembourg were studied by high-performance liquid chromatography (HPLC) to reveal the possibilities of growing tartary buckwheat herb as a possible source of rutin, quercetin, and quercitrin. The content of rutin was determined as up to 3% dry weight (DW) in tartary buckwheat herb. Quercitrin values were in the range of 0.01-0.05% DW. Only traces of quercetin were detected in just some of the samples. Tartary buckwheat seeds contained more rutin (about 0.8-1.7% DW) than common buckwheat seeds (0.01% DW). Rutin and quercetin content in seeds depends on variety and growing conditions. Tartary buckwheat seeds contained traces of quercitrin and quercetin, which were not found in common buckwheat seeds.     

黑苦荞米黄酮提取工艺优化及其降血糖活性研究

为了获得合适的黑苦荞米黄酮提取工艺,该文采用单因素试验和响应面设计,选择乙醇体积分数、料液比、提取时间、提取温度4个因素,优化黑苦荞米黄酮提取工艺。试验结果表明,黑苦荞米黄酮的最佳提取条件是:乙醇体积分数54%,料液比1:24 g/m L,提取时间62 min,提取温度71℃。在此条件下,理论黄酮得率为2.21%,实际黄酮得率为2.20%,相对误差为0.45%。在此基础上进一步研究了黑苦荞米黄酮的α-淀粉酶抑制活性,结果表明7.5 mg/m L的黑苦荞米黄酮对α-淀粉酶活性的抑制率为54.05%,与二甲双胍(5 mg/m L)效果相当;此外,与空白对照相比,50μg/m L黑苦荞米黄酮能显著(P0.05)提高肝脏细胞Hep G2的葡萄糖消耗量(48.73%),并促进肝脏细胞糖原的合成。研究结果表明,黑苦荞米黄酮具有较好的辅助降血糖功效。     

Metabolomic analysis of phenolic compounds in buckwheat (Fagopyrum esculentum M.) sprouts treated with methyl jasmonate

The effects of exogenous methyl jasmonate (MeJA) on phytochemical production in buckwheat sprouts cultivated under dark conditions (0, 1, 3, 5, and 7 d) were investigated by metabolomic analysis, using ultra performance liquid chromatography-quadrupole-time-of-flight (UPLC-Q-TOF) mass spectroscopy (MS) and partial least-squares-discriminant analysis (PLS-DA). MeJA-treated and control groups showed no differences in growth but were clearly discriminated from each other on PLS-DA score plots. The metabolites contributing to the discrimination were assigned as chlorogenic acid, catechin, isoorientin, orientin, rutin, vitexin, and quercitrin, which have various health effects. Moreover, isoorientin, orientin, rutin, and vitexin were assigned as the main phytochemicals of sprouts cultivated under dark conditions. The accumulation of these metabolites caused the phenolic compound content and antioxidant activity of the sprouts to increase. Further, this study revealed that their accumulation resulted from the stimulation of the phenylpropanoid pathway by MeJA treatment. Therefore, these metabolites may be useful for better understanding the effects of MeJA on buckwheat sprout phytochemicals and contribute to improving the functional quality of the sprouts.     

Application of near-infrared reflectance spectroscopy to the evaluation of rutin and D-chiro-Inositol contents in tartary buckwheat

Tartary buckwheat [Fagopyrum tataricum (L.) Gaench] is rich in rutin and D- chiro-inositol (DCI), which have beneficial effects in the treatment of hemorrhagic diseases and insulin-resistant diseases, respectively. The current methods of extraction and detection of rutin and DCI are complex and time-consuming; a simple way of analyzing these compounds in the native matrix would be desirable. In this work, near-infrared reflectance spectroscopy (NIRS) was applied to determine the contents of rutin and DCI in tartary buckwheat. The spectral data were compared with those determined from high-performance liquid chromatography (HPLC) methods. Models for predicting rutin and DCI contents in buckwheat were developed using a partial least-squares algorithm. Cross-validation procedures indicated good correlations between HPLC data and NIRS predictions (R2 = 0.76 for rutin and R2 = 0.86 for DCI). The rutin content ranged from 0.998 to 1.75%, while the DCI content covered 0.179-0.200%. The results showed that NIRS, a well-established and widely applied technique, could be applied to determine rutin and DCI in tartary buckwheat rapidly and nondestructively.     

Social and environmental influences on tartary buckwheat (<Emphasis Type="Italic">Fagopyrum tataricum</Emphasis> Gaertn.) varietal diversity in Yunnan,China

Effective conservation strategies aimed to protect crop genetic resources require multiple sources of information. We used a combination of AFLP genotyping and farmer surveys to understand the extent, distribution and management of tartary buckwheat (Fagopyrum tataricum Gaertn.) diversity in its center of origin in Yunnan Province, China. We found genetic evidence of gene flow in tartary buckwheat throughout the study area, with small but statistically significant regional and village-level components. We also found genetic differentiation by seed color. Although most farmers reported exchanging seed in localized kinship networks, our results imply homogenizing gene flow is occurring. Yi ethnic farmers tend to plant more buckwheat than non-Yi farmers, and we found that in some communities, Yi farmers serve as seed sources for farmers of other ethnicities. Different tartary buckwheat varieties did not have different end uses; rather farmers maintained varietal diversity in order to protect crop yield and quality. Individual farmers’ seed exchange practices reflect their ideas about components of seed quality, as well as priorities in protecting buckwheat yield. From the standpoint of genetic resources conservation, the presence of a culturally rich farmer exchange network and hierarchical structuring of tartary buckwheat genetic diversity demonstrates the importance of maintaining an interlinked community of tartary buckwheat farmers in Yunnan.     

Use of cyclic voltammetry, photochemiluminescence, and spectrophotometric methods for the measurement of the antioxidant capacity of buckwheat sprouts

This paper describes the use of cyclic voltammetry, photochemiluminescence (PCL), and spectrophotometric methods (TEAC and FCR reducing capacity) for the measurement of the antioxidant capacity of dark- and light-grown buckwheat sprouts. Moreover, the flavonoid profile of studied material is provided. Methanol extracts (80%) from ungerminated buckwheat grain and 6 and 8 DAS (days after seeding) sprouts were used. The 8 day germination period was sufficient to obtain good quality sprouts with completely removed pericarps. The ungerminated buckwheat grain contained only rutin, whereas in sprouts produced in dark or light, a high level of isoorientin, orientin, vitexin, rutin, and isovitexin was found. The flavonoid content in sprouts produced under light was almost 2 times higher than those of sprouts produced in the dark. The antioxidant capacity of light-grown sprouts was higher than that of dark-grown ones. The results from voltammetric experiments obtained for buckwheat seeds and 6 and 8 DAS sprouts harvested under dark or light conditions highly correlated with those obtained by PCL antioxidant capacity of water-soluble substances (PCL ACW) (r = 0.99), PCL antioxidant capacity of lipid-soluble substances (r = 0.99), TEAC (r = 0.99), and FCR reducing capacity (r = 0.99). The use of cyclic voltammetry, PCL ACW, and TEAC was fully applicable for the evaluation of the antioxidant capacity of buckwheat sprouts.     

Effect of buckwheat extract on the antioxidant activity of lipid in mouse brain and its structural change during in vitro human digestion

This study was conducted to investigate the effects of buckwheat ( Fagopyrum esculentum Moench cv. Yangjul No. 2) extract on the antioxidant activity of lipids in mouse brain and the structural change during in vitro human digestion. Buckwheat was collected from a wild farm and extracted with water. The buckwheat extracts were then passed through an in vitro human digestion model that simulated the composition of the mouth, stomach, and small intestine juice. The results confirmed that the main phenolics of buckwheat extract were rutin, quercitrin, and quercetin. The rutin content increased with digestion of the buckwheat (from 48.82 to 96.34 μg/g) and rutin standard samples (from 92.76 to 556.56 μg/g). Antioxidant activity was more strongly influenced by in vitro human digestion of both buckwheat and rutin standard. After digestion by the small intestine, the antioxidant activity values were dramatically increased (from 5.06 to 87.82%), whereas the antioxidant activity was not influenced by digestion in the stomach for both buckwheat extract and rutin standard. Inhibition of lipid oxidation of buckwheat in mouse brain lipids increased after digestion in the stomach for both buckwheat extract and the rutin standard. The major finding of this study was that in vitro human digestion may be an important modulator of the antioxidant capacity of buckwheat and that this may be because in vitro human digestion increased the antioxidative activity via an increase in antioxidants such as rutin and quercetin.     

电解水对荞麦芽酚酸含量及抗氧化能力的影响

为了能够更好地将发芽荞麦用作制备功能食品的原料,本研究采用理化指标不同的电解水制备荞麦芽,考察荞麦的发芽率及芽长、总酚含量、DPPH和ABTS自由基清除能力,以及铁离子还原力在发芽期间的动态变化,并分析各处理组发芽第7天荞麦芽中游离酚和结合酚种类和含量。结果表明,在7 d观测期内,电解水有利于荞麦发芽及生长。不同评价方法测定荞麦芽抗氧化能力的结果显示,pH值11.13电解水处理组发芽1~3 d荞麦芽总酚含量及抗氧化水平均显著高于对照组(P<0.05),而pH值3.21、pH值5.02和pH值9.02电解水处理组发芽5~7 d荞麦芽总酚含量及抗氧化水平均显著高于对照组(P<0.05)。各处理组荞麦芽中主要的游离酚均为绿原酸,且电解水处理组荞麦芽游离绿原酸含量均显著高于对照组(P<0.05)。自来水处理组荞麦芽主要结合酚为香豆酸,而电解水处理组荞麦芽主要结合酚为咖啡酸。本研究结果为电解水应用于功能性荞麦芽的制备提供了理论依据。     

Bioguided Fraction of Antioxidant Activity of Ethanol Extract from Tartary Buckwheat Bran

This study describes the activity‐guided isolation of antioxidant agents from tartary buckwheat bran (TBB). The ethanol crude extract of oil‐free TBB was partitioned sequentially into ethyl acetate, n‐butanol, and residual aqueous fractions. The ethyl acetate fraction (EAF) had the highest phenolic and flavonoid contents and showed the strongest antioxidant activity. EAF was superior to rutin and inferior to vitamin C (Vc) in DPPH radical scavenging ability, had an advantage over rutin and Vc in ABTS radical scavenging ability, and again surpassed rutin and quercetin in reducing power. Then EAF was subjected to column chromatography, and isolated compounds were identified using nuclear magnetic resonance data by comparing with those reported in the literature. Finally, the bioassay‐guided fractionation of the crude ethanol extract of TBB afforded three known compounds (quercetin, p‐hydroxybenzoic acid, and daucosterol) responsible for antioxidant activity. p‐Hydroxybenzoic acid and daucosterol were isolated from buckwheat grain for the first time. Taken together, establishing of the three pure compounds is of paramount importance to the understanding of antioxidant activity of TBB, and there is an immense potential to process TBB or its EAF into value‐added functional foods and beverages.     

Physicochemical Properties of Common and Tartary Buckwheat Starch

Physicochemical properties of starch of three common (Fagopyrum esculentum) and three tartary (F. tataricum) buckwheat varieties from Shanxi Province, China, were compared. Starch color, especially b*, differed greatly between tartary (7.99–9.57) and common (1.97–2.42) buckwheat, indicating that removal of yellow pigments from tartary buckwheat flour may be problematic during starch isolation. Starch swelling volume in water of reference wheat starch (2.8% solids and 92.5°C) was 20.1 mL; for the three common buckwheat starches it was 27.4–28.0 mL; and for the three tartary buckwheat starches it was 26.5–30.8 mL. Peak gelatinization temperature (T_p) in water was 63.7°C for wheat starch, 66.3–68.8°C for common buckwheat and 68.8–70.8°C for tartary buckwheat. T_p of all samples was similarly delayed (by 4.0–4.8°C) by 1% NaCl. Enthalpy of gelatinization (ΔH) was higher for all six buckwheat starches than it was for wheat starch. However, one common buckwheat sample had significantly lower ΔH than the others. Starch pasting profiles, measured by a Rapid Visco-Analyzer, were characteristic and similar for all six buckwheat starches, and very different from the reference wheat starch. A comparison of pasting characteristics of common and tartary buckwheat starches to wheat starch indicated similar peak viscosity, higher hot paste viscosity, higher cool paste viscosity, smaller effect of NaCl on peak viscosity, and higher resistance to shear thinning. Texture profile analysis of starch gels showed significantly greater hardness for all buckwheat samples when compared to wheat starch.     

硒对苦荞硒、总黄酮和芦丁含量、分布与累积的影响

采用盆栽试验探讨土壤施硒对苦荞硒、总黄酮和芦丁含量、分布与累积的影响。结果看出,在土壤施硒0.5～2.0 mg/kg范围,苦荞根在苗期（40 d）大量吸收并累积硒,全生育期各器官硒含量极显著提高;在生长中后期(60～80 d) 硒的累积最快,累积量最多。硒在苦荞各器官中的分布为:在40 d时,根＞叶＞茎;60 d时Se0.0处理为叶＞根＞花＞茎,施硒各处理则为花＞根＞叶＞茎;80 d时Se0.0处理以花＞根＞叶＞茎＞子粒,Se0.5处理以花＞叶＞子粒＞茎＞根,施硒≥1.0 mg/kg的处理则为花＞叶＞茎＞根＞子粒。土壤施硒≤1.0 mg/kg促进苦荞生长,提高地上部各器官干重和植株总干重以及各器官总黄酮和芦丁含量与累积量,不改变总黄酮和芦丁的器官分布,增加苦荞中后期对总黄酮的累积;以Se0.5处理效应最佳,各差异达显著水平。过量的硒（Se1.5～2.0 mg/kg）显著抑制苦荞生长,降低各器官干重、总黄酮和芦丁含量与累积,不利于硒在子粒中富集和总黄酮在子粒中分布。表明在低硒土壤上栽培苦荞,土壤施硒以不超过1.0 mg/kg为宜,既能最大限度的提高苦荞各器官硒、总黄酮和芦丁含量和累积量,又可降低施用硒肥的成本和减少硒肥对环境的影响。     

Identification of anthocyanins in the sprouts of buckwheat

The anthocyanin profiles and varieties/breeding line differences of anthocyanin concentrations in common/tartary buckwheat sprouts have been studied. Four anthocyanins, cyanidin 3-O-glucoside, cyanidin 3-O-rutinoside, cyanidin 3-O-galactoside, and cyanidin 3-O-galactopyranosyl-rhamnoside, were isolated from the sprouts of common buckwheat, were separated using high-performance liquid chromatography (HPLC), and were identified using reversed-phase liquid chromatography (LC)/electrospray ionization-mass spectrometry (ESI-MS)/MS techniques. In tartary buckwheat sprouts, two anthocyanins (cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside) were identified. Among 19 common/tartary buckwheat varieties/breeding lines, Hokkai T10 contained the highest amounts of anthocyanins. Cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside concentrations in 6-10 days after seeding sprouts of Hokkai T10 ranged from 0.16 to 0.20 mg/g dry wt and from 5.55 to 6.57 mg/g dry wt, respectively. In addition, dark-grown sprouts of Hokkai T10 accumulated 0.091 and 2.77 mg/g dry wt of cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside whereas other varieties/breeding lines accumulated trace amounts of anthocyanins. Given its anthocyanin-rich red cotyledons, Hokkai T10 is a promising line for use as "Moyashi" type sprouts and is strongly recommended as a new functional food, rich in dietary anthocyanins.     

Fagopyritols, D-chiro-inositol, and other soluble carbohydrates in buckwheat seed milling fractions

Fagopyritols are mono-, di-, and trigalactosyl derivatives of D-chiro-inositol that accumulate in seeds of common buckwheat (Fagopyrum esculentum Moench) and may be important for seed maturation and as a dietary supplement. Fagopyritols and other soluble carbohydrates were assayed in mature groats and 11 milling fractions of common buckwheat seed. Because fagopyritols are in embryo and aleurone tissues, differences in fagopyritol concentrations reflect varying proportions of these tissues in each milling fraction. Bran milling fractions contained 6.4 g of total soluble carbohydrates per 100 g of dry weight, 55% of which was sucrose and 40% fagopyritols. Flour milling fractions had reduced fagopyritol concentration [0.7 g/100 g of dry weight total fagopyritols in the dark (Supreme) flour and 0.3 g/100 g in the light (Fancy) flours]. Fagopyritol B1 was 70% of total fagopyritols in all milling fractions. Fagopyritols were 40% of total soluble carbohydrates in groats of two cultivars of common buckwheat but 21% in groats of tartary buckwheat [Fagopyrum tataricum (L.) Gaertn.], probably a reflection of environment and genetics. A rhamnoglucoside present in tartary buckwheat was not detected in common buckwheat.     

Determination of rutin, catechin, epicatechin, and epicatechin gallate in buckwheat Fagopyrum esculentum Moench by micro-high-performance liquid chromatography with electrochemical detection

A simple and sensitive method has been developed for determining rutin, catechin, epicatechin, and epicatechin gallate in buckwheat (Fagopyrum esculentum Moench) flour and seeds by micro-high-performance liquid chromatography with electrochemical detection. Chromatography was performed using an octadecylsilica column, acetonitrile-water-formic acid (13:87:1, v/v/v) as a mobile phase, and an applied potential at +0.5 V vs Ag/AgCl. We found that Japanese buckwheat flour contains rutin (12.7 mg/100 g), catechin (3.30 mg/100 g), epicatechin (20.5 mg/100 g), and epicatechin gallate (1.27 mg/100 g). The relative standard deviations for rutin, catechin, epicatechin, and epicatechin gallate peak heights were less than 0.86% (n = 5). The detection limit of rutin was 0.86 ng/mL. Moreover, the present method was applied to the distribution analysis of these compounds in buckwheat seed. The embryo proper and cotyledons of a mature buckwheat seed contained rutin with the highest concentration as compared to other parts. This method is useful in determining rutin, catechin, epicatechin, and epicatechin gallate in buckwheat with a small amount of sample for quality control in the food industry.     

超微粉碎对苦荞麸功能特性的影响

为研究超微粉碎处理对苦养麸中功能成分的溶出、清除有毒有害物及抗氧化功能特性的影响。将苦养麸皮原粉进行超微粉碎处理得到苦养麸微粉,比较不同粒度的苦养微粉与麸皮原粉中总黄酮提取率、在体外对胆酸钠、Pb^2＋、Cd^2＋、Hg^2＋的吸附力以及对NO2^-、2,2-联苯-1-三砂基苯肼（DPPH）的清除力。结果表明,与苦养麸皮原粉相比,苦养麸微粉（平均粒径为20．621μm）的总黄酮提取率增加0．36个百分点;对胆酸钠的吸附量降低5．60mg／g;对Pb^2＋、Cd^2＋、Hg^2＋的吸附量增加0．184、0．840、1．341mg／g;对NO2的清除率增加24．25个百分点;对DPPH的清除率增加53．56个百分点。超微粉碎处理适合苦养麸皮的深加工;得到苦养麸微粉具有优良的营养、功能特性,是一种极具开发潜力的功能食品原料。     

Variation of major minerals and trace elements in seeds of tartary buckwheat (Fagopyrum tataricum Gaertn.)

Tartary buckwheat (Fagopyrum tataricum Gaertn.) contains protein of high nutritional value, polyphenols, vitamins and minerals. It is one of the most important minor crops in China and has a great potential as a health and functional food. However, information on the elemental mineral composition of its seeds remains limited. The concentrations of Cu, Zn, Fe, K, and Mg in seeds of 123 tartary buckwheat accessions from the same cultivation were studied by means of flame atomic absorption spectrometry. The results revealed that the average concentrations of Cu (x₁), Zn (x₂), Fe (x₃), K (x₄), and Mg (x₅) elements in the accessions are 19.49 (with a range of 5.74–36.01 mg/kg), 27.41 (8.44–66.63 mg/kg), 656.24 (21.8–3,990 mg/kg), 3,639.23 (1,737–5,831 mg/kg), and 1,523.89 mg/kg (729–3,104 mg/kg) respectively. Among them, Fe concentration has the highest coefficient of variation (114.7 %). The results also revealed five significant positive correlations among Cu, Zn, Fe, K, and Mg concentrations. Therefore, distinct genotypes with high concentration of mineral elements should be effective for the development of special buckwheat varieties and improvement of its food nutritional quality.     

荞麦和金荞麦根际土壤铝形态变化及对其生长的影响

不同形态的铝对不同植物的毒害不同。以荞麦和金荞麦为实验材料,设置4个不同的土壤铝处理浓度（0,0.1,0.2,0.4 g Al^3＋/kg）,研究荞麦和金荞麦根际土壤中铝形态变化及对其生长的影响。结果表明,当土壤铝处理浓度〈0.2 g/kg时,尽管根际土壤液中铝溶出量较对照组有明显上升,毒性大的交换态铝和单聚体羟基铝（称为活性铝）占可提取铝总量的比例增加,但荞麦和金荞麦茎伸长和水分利用增强,地上部分生物积累量增多,表明荞麦和金荞麦对低铝胁迫有一定的适应;当土壤铝处理浓度达到0.4 g/kg时,荞麦和金荞麦根际土壤pH降至最低,根际土壤液中铝的溶出量增至最高,严重抑制了荞麦和金荞麦叶片光合作用的正常进行,各项指标和对照差异达到显著水平,荞麦和金荞麦的生长表现出明显的铝毒害症状。因此,我们推断在根际土壤活性铝溶出量为0.106-0.143 m g/g和0.046-0.057 m g/g间可能分别存在着荞麦和金荞麦耐受铝毒害的某个阈值。     

Determination of D-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.