Screening non-colored phenolics in red wines using liquid chromatography/ultraviolet and mass spectrometry/mass spectrometry libraries

Liquid chromatography/ultraviolet (LC/UV) and mass spectrometry/mass spectrometry (MS/MS) libraries containing 39 phenolic compounds were established by coupling a LC and an ion trap MS with an electrospray ionization (ESI) source, operated in negative ion mode. As a result, the deprotonated [M-H]- molecule was observed for all the analyzed compounds. Using MS/MS hydroxybenzoic acid and hydroxycinnamic acids showed a loss of CO2 and production of a [M-H-44]- fragment and as expected, the UV spectra of these two compounds were affected by their chemical structures. For flavonol and flavonol glycosides, the spectra of their glycosides and aglycones produced deprotonated [M-H]- and [A-H]- species, respectively, and their UV spectra each presented two major absorption peaks. The UV spectra and MS/MS data of flavan-3-ols and stilbenes were also investigated. Using the optimized LC/MS/MS analytical conditions, the phenolic extracts from six representative wine samples were analyzed and 31 phenolic compounds were detected, 26 of which were identified by searching the LC/UV and MS/MS libraries. Finally, the presence of phenolic compounds was confirmed in different wine samples using the LC/UV and LC/MS/MS libraries.     

Determination of 19 rhubarb constituents by high-performance liquid chromatography-ultraviolet-mass spectrometry

Rhubarb (Rhei rhizoma), a commonly used Chinese herb, contains anthraquinones, anthrones, galloylglucoses, stilbenes, and flavan-3-ols compounds, etc. as major constituents. Using 19 of these compounds as markers, an HPLC-UV-MS method was developed to estimate the quality of rhubarb samples within a period of 70 min. Extracts were analyzed with a Cosmosil 5C18-MS column and eluted with a gradient comprising an aqueous solution of acetic acid and methanol at a flow rate of 0.9 mL/min. Peaks were detected by absorbance measurements at 254 nm (6 and 8-19) and 280 nm (1-5 and 7), and the peaks of the marker substances were identified from their UV spectra and MS fragmentation patterns. The proposed method yielded a peak-area ratio RSD value with an intraday SD falling within 0.71-1.78% and an interday SD within 0.78-1.98% at a detection limit of 0.2-3.2 microg/mL. The ESI negative ion mode was used to collect data (molecular weight, CID fragments from MS and MS/MS spectra) for 19 compounds from four types of structure categories: anthraquinones, dianthrone glycosides, stilbenes, and galloylglucosides. The information gathered can be used to identify the structures of various peaks appearing in the LC chromatograms of rhubarb samples.     

Kaempferol glycosides in the flowers of carnation and their contribution to the creamy white flower color

Three flavonol glycosides were isolated from the flowers of carnation cultivars 'White Wink' and 'Honey Moon'. They were identified from their UV, MS, 1H and 13C NMR spectra as kaempferol 3-O-neohesperidoside, kaempferol 3-O-sophoroside and kaempferol 3-O-glucosyl-(1 --> 2)-[rhamnosyl-(1 --> 6)-glucoside]. Referring to previous reports, flavonols occurring in carnation flowers are characterized as kaempferol 3-O-glucosides with additional sugars binding at the 2 and/or 6-positions of the glucose. The kaempferol glycoside contents of a nearly pure white flower and some creamy white flower lines were compared. Although the major glycoside was different in each line, the total kaempferol contents of the creamy white lines were from 5.9 to 20.9 times higher than the pure white line. Thus, in carnations, kaempferol glycosides surely contribute to the creamy tone of white flowers.     

在线提取-高效液相色谱-二极管阵列检测-四极杆飞行时间质谱法快速鉴定陈皮中黄酮类化合物

建立了简便、高效的在线提取-高效液相色谱-二极管阵列-四极杆飞行时间质谱法(OLE-HPLC-DAD-QTOFMS)快速提取和分离鉴定陈皮中黄酮类化合物。在线提取体系中,将填有陈皮粉末样品(2.0 mg)的固相萃取小柱取代样品环连接在手动进样阀上,样品直接被流动相提取并进入HPLC-DAD-QTOF-MS系统分析,无需额外的样品前处理步骤。与传统的溶剂回流提取法相比,在线提取法具有较高的提取率。通过分析化合物的紫外谱图、色谱保留时间和质谱信息,共鉴定出24种黄酮类化合物,其中新圣草次苷、柠檬黄素-3-O-(3-羟基-3-甲基戊二酸)-葡萄糖苷及其异构体首次在陈皮中报道。建立的方法为中药复杂体系中活性成分的快速分离鉴定提供了新的研究思路。     

Characterization and identification of saikosaponins in crude extracts from three Bupleurum species using LC-ESI-MS

A LC-diode array detection (DAD)-ESI-MS/MS method was established for the online characterization and identification of saikosaponins (SSs) from extracts of roots of Bupleurum scorzonerifolium Willd, B. marginatum var. stenophyllum and B. komarovianum. In ESI-MS/MS spectra of SSs, [M-H](- )ions were subjected to the cleavage of glycosidic bonds and produced Y type ions, which can be used to elucidate the structures of saccharide chains and aglycones. Fragmentation of aglycones provided mass information about their major substitutions. For three structural types of SSs, type III can be easily identified by their fragmentation behaviors; while type I and II often occur as isomers and they can be discriminated by their typical UV absorption data. The only sugar ring-cross cleavage corresponding to 76 Da took place at a furanose sugar moiety. As a result, more than 75 SSs, including eight novel compounds, were identified or tentatively characterized based on their UV and mass spectra and retention times. The approach established here allows a comprehensive analysis of the SSs in the genus of Bupleurum and will be helpful for quality control of the crude materials and their related preparations.     

天麻中对羟基苯类化合物的高效液相色谱-质谱研究

天麻中对羟基苯类化合物的(EsI(-))一级质谱图中除分子离子峰[M-1]外，还可见明显的[M-1 20] m[2m-1]峰，由此规律可方便确证未知同类样品的分子离子峰。由二级质谱(ESI/MS/MS)的特征碎片离子93、105和107等，结合紫外光谱及核磁结果确定了3个不纯样品中主要成分的结构，同时初步确定了两个同类杂质的结构。     

Analysis of Paeoniae Radix by high-performance liquid chromatography-electrospray ionization-mass spectrometry.

A method has been developed for the qualitative analysis of paeonol, paeoniflorin and their derivatives in Paeoniae Radix by high-performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS). Gradient elution with acetonitrile-water solvent system was employed in an HPLC-ESI-MS study. The negative-ion ESI mode was suitable for these compounds. The peaks were identified by their mass spectra, UV spectra and fragments of their MS2 spectra. The structures of three unknown compounds are inferred in this paper.     

Two New Alkaloids from Flueggea virosa

Two new securinega‐type alkaloids and four known ones were isolated from the twigs and leaves of Flueggea virosa. The structures of the new compounds were elucidated by means of spectroscopic methods (UV, IR, HR‐ESI‐MS, and 1D‐ and 2D‐NMR), and the absolute configurations were assigned by CD spectra. The structures of the known compounds were identified by comparison of their physical and spectroscopic data with those reported in the literature.     

Characterization of fifty-one flavonoids in a Chinese herbal prescription Longdan Xiegan Decoction by high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry and photodiode array detection

High-performance liquid chromatography coupled to electrospray ionization (ESI) tandem mass spectrometry and photodiode array detection (HPLC-DAD-ESI-MS(n)) was developed to identify and characterize the flavonoids in a Chinese formulated preparation, Longdan Xiegan Decoction (LXD). In total, fifty-one flavonoids (27 flavones, 10 flavanones, 7 chalcones, 5 flavonols and 2 isoflavones) were characterized. Eighteen compounds among them including a newly detected flavonoid, naringin, from the ingredient herbs, were unambiguously determined by comparing the retention times (t(R)), UV spectral data and mass fragmentation behaviors with those of the reference compounds. Another thirty-three compounds were tentatively identified by referencing to the reported data of their UV and MS spectra. The ESI-MS/MS fragmentation behavior of flavones (OMe-substituted, O-glycosides, C-glycosides), chalcones, flavonols and their appropriate characteristic pathways were proposed. In negative ion ESI-MS all the flavonoids yielded prominent [M--H](-) ions in the first order mass spectra. Fragmentation with a loss of mass of 15 Da (CH(3)), 18 Da (H(2)O), 28 Da (CO), 44 Da (CO(2)), 56 Da (2CO) and the residues of glucose and glucuronic acid observed in the MS/MS spectra were useful for aiding the structural identification of the flavonoids investigated.