Optimization of two-dimensional gradient liquid chromatography separations

An almost orthogonal comprehensive two-dimensional liquid chromatography was developed for the separation of phenolic and flavone natural antioxidants by using combinations of a polyethylene glycol silica micro-column in the first dimension and a porous-shell fused-core C18 column in the second dimension, both in the reversed-phase mode. System orthogonality was improved using parallel gradients of acetonitrile in buffered mobile phase. A new approach was proposed to optimize matching segmented gradient profiles in the two dimensions. An algorithm was developed for automatic corrections of the shifts in retention in the second dimension induced by the parallel two-dimensional gradient operation technique. Using the porous-shell C18 column in the second dimension at elevated temperature (60 degrees C) and high pressure (480 bar) with optimized segmented profiles of the parallel gradients in the two dimensions, the overall separation time for comprehensive LC x LC was reduced to 30 min.     

超声辅助法提取白筋茎皮总黄酮的工艺研究

采用超声辅助法提取白霸茎皮中总黄酮化合物,通过单因素试验和正交试验,研究了超声提取条件（超声功率,乙醇浓度,料液比,时间）对其中总黄酮提取的影响。白筋茎皮总黄酮最佳提取工艺为：料液比1：30．乙醇浓度70％,超声功率120W,提取时间25min。在此工艺条件下提取,总黄酮含量为53．0843mg／g。     

蒙药匝迪-5和八味三香散总黄酮含量的测定

本文用70%乙醇分别提取了匝迪-5和八味三香散的类黄酮物质。分别用活性炭、活性白土等脱色、除杂,用硝酸铝-亚硝酸钠方法对黄酮的含量进行了测定,求得其校准曲线的回归方程为y=0.0094x-0.0023,r=0.9995,线性范围在3.08—21.56μg/mL。匝迪-5总黄酮含量为2.45%,平均回收率98.6%,相对标准偏差为0.65%(n=5);八味三香散总黄酮含量为4.5%,平均回收率为99.6%,RSD=0.87%(n=5)。     

Ultrasonic-assisted synthesis of flavones by oxidative cyclization of 2′-hydroxychalcones using iodine monochloride

This paper presents an efficient methodology for the synthesis of flavones via the oxidative cyclization of 2′-hydroxychalcones in the presence of iodine monochloride with DMSO under ultrasound irradiation. Ultrasonic irradiation enhances the cyclization reaction and leads to reduced reaction time at lower reaction temperatures while generating flavones with high yields.     

沙棘黄酮口服液中芦丁和5-羟色胺的毛细管区带电泳电化学检测

建立了毛细管区带电泳 -电化学检测法 (CE -ED)测定芦丁和5_羟色胺含量的方法 ,研究了电极电位、运行缓冲液的酸度和浓度、电泳电压及进样时间等因素对分离检测的影响,确定了最佳测定条件 ;以直径为300μm的碳圆盘电极为检测电极,电极电位为0.90V(vsSCE),在50mmol/L硼酸盐缓冲液(pH8.5)中,上述2组分在12min内完全分离 ,被分析物的电流响应与浓度在约3个数量级范围内呈良好线性关系,检出限分别为3×10-7 mol/L和8×10-8 mol/L ,7次测定含5.0×10-4 mol/L的芦丁和5_羟色胺的标准溶液,峰高的相对标准偏差分别为2.5 %和3.8 % ;该法成功地用于中药沙棘黄酮口服液中芦丁和5_羟色胺的测定     

Isolation and characterization of methoxylated flavones in the flowers of Primula veris by liquid chromatography and mass spectrometry

Characterization of six flavones, which were named substances G1, G2, G3, G4, G5 and G6 according to their R_F values in normal-phase thin-layer chromatography, is reported. The pure flavones were purified after maceration with methanol by normal-phase solid-phase extraction, normal-phase medium-pressure liquid chromatography, normal-phase preparative thin-layer chromatography and preparative reversed-phase high-performance liquid chromatography (RP-HPLC). The collected fractions of several isolation steps were analyzed by normal-phase (NP) and RP-HPLC. Detection and identification of the substances G was accomplished by UV detection at 213–216 nm, diode array UV detection, or fluorescence detection (λ_ex=330 nm; λ_em=440 nm). The molecular mass, the elementary composition, and the structure of the six components was determined by electron-impact high-resolution mass spectrometry (EI-HRMS). Substance G4 was identified as 3′,4′,5′-trimethoxyflavone. The substances G1–G6 were shown to be mono-, di- tri- and pentamethoxyflavones. HPLC–electrospray ionization tandem mass spectrometry (ESI-MS–MS) of the flavones was carried out employing a 150×2 mm I.D. column packed with a 3 μm/100 Å octadecylsilica stationary phase and a mobile phase comprising 1.0% acetic acid in water–acetonitrile (50:50). Comparative RP-HPLC–ESI-MS of the raw methanol extract and the isolated substances G1–G6 proved that the isolated compounds were pure and were not artifacts. Finally, RP-HPLC–ESI-MS–MS was used to identify substances G1–G6 in phytopharmaceutical drugs.     

Cytotoxic and anti-HIV-1 constituents from leaves and twigs of Gardenia tubifera

Two new natural cycloartanes, tubiferolide methyl ester (1) and tubiferaoctanolide (2), together with the known coronalolide (3) and coronalolide methyl ester (4) have been isolated from leaves and twigs of Gardenia tubifera. In addition, a new flavone 5,3′,5′-trihydroxy-7,4′-dimethoxyflavone (5), five known flavones 6-10 and hexacosyl 4′-hydroxy-trans-cinnamate (11) were also obtained from the same source. The structures were assigned on the basis of spectroscopic methods. Compounds 3, 7, 9, and 10 showed significant cytotoxic activities only in P-388 cell line. Compound 1 was cytotoxic against P-388, KB, Col-2 and Lu-1, while 4 was active in P-388 and BCA-1. Compounds 3 and 4 displayed significant anti-HIV activities in the HIV-1RT assay; compound 7 showed moderate activity in this assay. Compounds 5-10 were also found to be active in the ^ΔTat/RevMC 99 syncytium assay.     

LC-DAD UV and LC-MS for the Analysis of Isoflavones and Flavones from In Vitro and In Vivo Biomass of Genista tinctoria L.

Conditions were determined for the separation of a complex set of isoflavones and flavones (free aglycones, monoglucosides, diglucosides and esters) by HPLC-DAD UV and MS detection. A good separation of all analytes was obtained and satisfactory peak shapes were achieved by gradient elution on an RP C18 column. The method was then applied to carry out qualitative and quantitative analysis of bioflavonoids present in the herb and in vitro cultures of Genista tinctoria L. Electrospray ionisation mass spectrometry in the negative mode was used to identify individual flavonoids in G. tinctoria plant material. Photodiode array detection was also utilised in flavonoid characterisation. All flavonoid compounds were then quantified using an internal standard. The method developed is useful for monitoring the process of flavonoid biosynthesis in biomass obtained through in vitro cultures.     

Separation of rutin nona(H-) and deca(H-) sulfonate sodium by ion-pairing reversed-phase liquid chromatography

Ion-pairing reversed-phase liquid chromatography (RPLC) was used to separate two polysulfonates, rutin nona(H-) sulfonate sodium and rutin deca(H-) sulfonate sodium, which have very similar chemical structures. The final product always contained both of them when one of the compounds was synthesized. Baseline separation was achieved on a C8-bonded silica column at ambient temperature. The eluent was acetonitrile-15 mM phosphate buffer solution containing 20 mM TBA (pH 6.0) (46:54, v/v). The calibration plot was linear in the concentration range 0.5-200 microg ml(-1) for both analytes. The limits of detection (LODs; 254 nm) were 0.03 microg ml(1-) for rutin nona(H-) sulfonate sodium and 0.04 microg ml(-1) for rutin deca(H-) sulfonate sodium. Three batches of rutin deca(H-) sulfonate sodium were analyzed using the assay; the results showed that the analytical performance is really satisfactory.     

Chemical Constituents from the Roots of Patrinia Rupestris

Phytochemical investigation of the roots of Patrinia rupestris afforded a new triterpenoid patrirupin A ( 1 ) and a new iridoid patrirupin B ( 2 ), as well as three known triterpenoids: 3‐oxo‐olean‐12‐en‐28‐oic acid ( 3 ), ursolic acid ( 4 ), α‐amyrin ( 5 ), three known iridoids: isovaltratum ( 6 ), 11‐ethoxyviburtinal ( 7 ), homobaldrinal ( 8 ), five known steroids: ergosterol ( 9 ), ergost‐6,22‐diene‐3β,5α,8α‐triol ( 10 ), 6‐hydroxenone ( 11 ), β‐sitosterol ( 12 ), daucosterol ( 13 ), and two known flavones: 1‐hydroxy‐5‐methoxy xanthen‐9‐one ( 14 ), 3′,4′,5,7‐tetrahydroxyflavanone ( 15 ). The new compounds were characterized by means of spectroscopic methods including UV, IR, 1D, 2D NMR and HRESIMS, and the known ones were established on the basis of comparing their NMR data with those of the corresponding compounds in the literature.