Amino acid composition,antinutrients and allergens in the peanut protein fraction obtained by an aqueous enzymatic process

Enzyme-assisted aqueous extraction (EAE) of peanut kernel was used to extract oil and protein. The aqueous fraction (AF) obtained by EAE had a better essential amino acid profile than the residues obtained by solvent extraction (Rs) and cold pressing (Rc). No major difference in the trypsin inhibitor activity among AF, Rs and Rc was observed; however, the trypsin inhibitor activity was drastically reduced in the residue obtained after EAE. AF was subjected to MALDI-TOF/MS, revealing it to be rich in peptides (107) with molecular masses from m/z 700 to 2369 Da. AF had an extremely low phytate content and was rich in peptides, which could be used as a food supplement. ESI-MS/MS data were used for the identification of major peanut allergens, viz., Ara h1, h3, h6–8. Their allergenic potential needs to be established.     

莲房原花色素的纯化分级和结构鉴定

莲房中原花色素经甲醇水提取,大孔树脂纯化,制得莲房原花色素提取物(LSPE),酸降解法测定其平均聚合度,并经TSK HW-40s凝胶树脂分级,高效液相色谱-二极管阵列检测器和电喷雾质谱分析。结果表明:采用60%甲醇水溶液,调整pH值至2.0,料液比1:20(m/V),在60℃提取1h,提取率可达7.65%,最适合纯化的树脂为AB-8。LSPE乙酸乙酯相和水相平均聚合度为3.2和15.4。LSPE乙酸乙酯相主要由儿茶素、没食子酸儿茶素、儿茶素和没食子酸儿茶素构成的二聚体、三聚体和少量四聚体构成。凝胶树脂将LSPE乙酸乙酯相分为11个级分(F1～F11),F1～F4可能为黄酮类及黄酮苷类,F5主要为儿茶素以及少量表儿茶素,F6为没食子酸儿茶素、原花青素二聚体B3、儿茶素,以及含有没食子酸儿茶素单元的原花色素,F7为儿茶素和原花青素B1、B2、B3,F8为原花色素类物质,F9～F11可能为儿茶素和没食子酸儿茶素组成的更高聚合度的聚合物。     

dTDP-L-鼠李糖生物合成路径的电喷雾多级串联质谱法表征

本研究以2’-脱氧胸苷-5’-二磷酸-L-鼠李糖（dTDP-L-Rha）生物合成路径涉及的系列酶促反应产物为研究对象,建立了电喷雾碰撞诱导解离串联质谱（CID-ESI-MSⁿ）对罕见单糖生物合成路径的表征方法。该方法首先通过ESI-MS技术分析2’-脱氧胸苷-5’-二磷酸-D-葡萄糖-4,6-脱氢酶（RmlB）、2’-脱氧胸苷-5’-二磷酸-4-酮-6-脱氧-葡萄糖-3,5异构酶（RmlC）和2’-脱氧胸苷-5’-二磷酸-4-酮-鼠李糖还原酶（RmlD）酶活产物的形成,随后应用CID-ESI-MSⁿ技术对酶促反应终产物L-鼠李糖（dTDP-L-Rha）的结构进行表征。结果表明：dTDP-L-Rha 的生物合成始于2’-脱氧胸苷-5’-二磷酸-D-葡萄糖（dTDP-D-Glc）,依次涉及RmlB、RmlC 和RmlD 三个酶的参与。这与传统的高效液相色谱法（HPLC）监测、纯化制备,核磁共振（NMR）及ESI-MS结构表征的分析结果一致。该方法简单、灵敏、快速,适用于重要罕见单糖生物合成路径的表征。     

Aqueous two-phase extraction,identification and antioxidant activity of anthocyanins from mulberry (Morus atropurpurea Roxb.)

Aqueous two-phase extraction (ATPE), identification and antioxidant activity of anthocyanins from mulberry (Morus atropurpurea Roxb.) were investigated in this study. The optimal differential partitioning of mulberry anthocyanins (MAY) and sugars was achieved in a system (pH 4.5, temperature = 35 ± 1 °C) composed of 30% (w/w) ethanol, 20% (w/w) concentration of ammonium sulphate, 10% (w/w) mulberry juice and 40% (w/w) water. The multiple partitioning indicated a single ATPE step could isolate the majority of anthocyanins, while removing near to 90% of the free sugars. The composition of the MAY extracted by ATPE had no obvious changes, and five anthocyanins were identified by HPLC–ESI-MS/MS. The ATPE extract showed a relatively high antioxidant ability compared to that by the conventional extraction. Our results indicated that ATPE was a valuable method for the removal of the majority of free sugars, which held great promise in the purification of natural anthocyanin pigments.     

质子化胞嘧啶碰撞诱导解离的实验和理论研究

在较高的去簇电压(DP)下,使用三重四极杆质谱仪通过电喷雾胞苷的甲醇-水溶液产生了质子化的胞嘧啶［C+H］⁺。［C+H］⁺的碰撞诱导解离过程共有4个相互竞争的解离通道,分别为脱去NH₃分子（-17 u）形成相对强度较高的碎片离子m/z 95;脱去异氢氰酸HNCO（-43 u）和H₂O（-18 u）分别形成m/z 69 和m/z 94;脱去C₂NH₃（-41 u）产生相对强度较低的碎片离子m/z 71,随后对这些碎片离子进行了结构确定。通过量化计算对该过程进行了模拟：首先,对9种质子化胞嘧啶的异构体进行了优化,并给出了它们之间异构化过程的势能面曲线; 其次,基于质子化胞嘧啶的初始结构对这4个解离通道进行了详细的模拟和推导。模拟结果表明,丢失NH₃、HNCO、H₂O和 C₂NH₃这4个解离通道的势垒分别为292.2、355.0、586.6和838.6 kJ/mol,此结果与质子化胞嘧啶碰撞诱导解离过程中产生的离子m/z 95、69、94和71的丰度大小基本一致。     

Tracking the Transformation Process of a Pair of Zn(II) Coordination Clusters: Crystallography and Mass Spectrometry

Two zinc clusters Zn₄(H₃L)₄(NO₃)₄?5H₂O ( Zn₄ , H₄L=(1,2‐bis(1H‐benzo[d]imidazol‐2‐yl)ethane‐1,2‐diol) and [Zn₅(H₂L′)₆](NO₃)₄]?8H₂O?2CH₃OH ( Zn₅ , H₃L′=(1,2‐bis(benzo[d] imidazol‐2‐yl)‐ethenol) have been obtained by the reaction of Zn(NO₃)₂?6H₂O with H₄L at 80 °C or 140 °C under solvothermal condition. Powder X‐ray Diffraction (PXRD) of precipitate and Electrospray Ionization Mass Spectrometry (ESI‐MS) of reaction solution revealed the existence of transformation behavior from Zn₄ to Zn₅ by increasing the temperature from 80 °C to 140 °C, or directly heating Zn₄ at 140 °C via solvothermal reaction. Here we proposed a possible mechanism involves split process of Zn₄ and reassembly to form Zn_{5 .} ESI‐MS for single crystals revealed [Zn₄(H₃L)₄?3H]⁺ splits to [Zn(H₃L)]⁺ via [Zn₂(H₃L)₂?H]⁺. Time dependent ESI‐MS of reaction solution revealed the [Zn(H₂L′)]⁺→[Zn₂(H₂L′)₂?H]⁺→[Zn₅(H₂L′)₆?H]³⁺ stepwise assembly. It also has been captured the in situ reaction mainly occurs in the step of [Zn(H₃L)]⁺ to [Zn(H₂L′)]⁺.     

HPLC/ESI-MS法鉴定半枝莲乙酸乙酯组分中黄酮苷元类化合物

利用正离子模式电喷雾质谱研究了包括正黄酮、异黄酮、二氢黄酮、异二氢黄酮和黄酮醇在内的5个黄酮亚类苷元的质谱断裂碎片,并得到了能够区别鉴定这5类黄酮苷元的特征碎片离子。其中,2个CO的连续丢失可以看作异黄酮的特征断裂,[^0,4B-H₂O+H]⁺是二氢黄酮的特征碎片离子,黄酮醇和异二氢黄酮则主要发生0,2键和2,3键的断裂,分别形成特征的^0,2A⁺和^2,3B⁺碎片离子。在此基础上,利用高效液相色谱与电喷雾质谱联用技术对半枝莲乙酸乙酯组分中的化合物进行研究,确定了异红花素 (isocarthamidin)、印黄芩素 (scutellarin)、木樨草素 (luteolin)、柚皮素 (naringenin)、4’-羟基汉黄芩素(4’-hydroxy-wogonin) 和芹菜素 (apigenin) 6个黄酮苷元,并结合紫外光谱信息和质谱碎片信息,对另外6个黄酮苷元类化合物进行初步的结构推断。     

川乌与贝母配伍禁忌的电喷雾质谱研究

The ESI-MS analytical method was established for studying the alkaloids content in the decoctions of Radix aconiti combined with Bulbus Fritillariae Thunbergii or Bulbus Fritillariae Cirrhosae. For the co-decoctions of Radix aconiti combined with Thunberg Fritillary Bulb contains more diester-alkaloids than that of co-decoctions of Radix aconiti combined with Bulbus Fritillariae Cirrhosae. When Radix aconiti was combined with Thunberg Fritillary Bulb, diester-alkaloids were mainly dissolved in water. But diester-alkaloids were mainly converted into lipo-alkaloids when Radix aconiti was combined with Bulbus Fritillariae Cirrhosae.     

Evolution of major phenolic components and radical scavenging activity of grape juices through concentration process and storage

The total phenolic (TP) and radical scavenging activity (RSA) of concentrated grape juices during process and storage were characterized and quantified. TP were determined using the Folin–Ciocalteu method and RSA by the DPPH assay. The main phenolic components of juices were investigated by direct infusion electrospray ionization-mass spectrometry (ESI-MS) in the negative ion mode. Concord juice (CJ) demonstrated higher RSA and TP contents than Isabel juice (IJ) with some differences at each processing step. During storage, retention of TP and RSA were 90% and 77% in CJ and of 81% and 86% in IJ, respectively. During processing, peonidin and peonidin-3-O-glucoside gave place to malvidin and dimethoxy-flavylium as major significant components; piceatannol-O-glucoside became significant after concentration and malvidin decreased after 8 months of storage. Concentrated and refrigerated storage were effective in preserving total phenolics and antioxidative status of grape juices, although changes in compounds were observed.     

高粱原花青素的ESI-MS分析及其低聚体的RP-HPLC-MS/MS法分离鉴定

以高粱加工后的副产物--高粱外种皮为原料,采用电子喷雾离子化质谱(electrospray ionization-mass spectroscopy,ESI-MS)对ADS-17大孔树脂纯化的高纯度高粱原花青素(sorghum procyanidins,SPC)的组成进行分析,并通过反相高效液相色谱(reverse phase high-performance liquid chromatography,RP-HPLC)-质谱(RP-HPLC-MS/MS)联用对Toyopearl HW-40凝胶色谱分离的SPC-5级分进行分离鉴定。结果显示：SPC为低聚体原花青素,包含有儿茶素/表儿茶素单体、原花青素二～六聚体;SPC-5由8种三聚体和1种二聚体组成。