Synthesis and anti-tubulin evaluation of chromone-based analogues of combretastatins

Twenty new hybrid compounds with both combretastatin and flavone moieties were synthesized. These derivatives are classified according to the position of the trimethoxyphenyl ring at C-2 or C-3 of the chromone and presence or absence of a carbonyl as a linker between C-3 and the aryl ring. Most of these compounds were prepared from hesperidin or naringin, two natural and abundant Citrus flavonoids. Seven of these combretastatin analogues revealed anti-tubulin activity but in a medium range.     

A two step synthesis of BzR/GABAergic active flavones via a Wacker-related oxidation

A general route for the synthesis of biologically important flavones is reported via a two step sequence employing a catalytic Wacker-Cook oxidation^4b as the key step.     

The synthesis, spectroscopic properties and X-ray structure of Zn(II) complexes with amino derivatives of chromone

Three new Zn(II) complexes containing the ligands 5-amino-8-methyl-4H-chromen-4-one (1), 6- or 7-amino-2-phenyl-4H-chromen-4-one (2, 3) were prepared. The new synthesised compounds were characterised by IR, ¹H NMR and MS spectroscopy. The crystal structure of complex 4 was determined with the use X-ray diffraction. The Zn(II) centre of 4 is linked by two chlorido and two N-bound aminochromone ligands, 1, in a strongly distorted tetrahedral configuration with the dissymetric point group C₂. The protonation constants of the ligands 1, 2 and 3 corresponded to 3.68, 3.88 and 6.83, respectively. The stability constants of the Zn(II) complexes were calculated from the potentiometric titration data. The complexes were found to have the formulae ML and ML₂ for ligands 1 and 2, and ML for ligand 3. Fluorescence spectroscopic properties were also studied; the strongest fluorescence in solution was exhibited by complex 6.     

Fast and simultaneous determination of phenolic compounds and caffeine in teas, mate, instant coffee, soft drink and energetic drink by high-performance liquid chromatography using a fused-core column

A fast HPLC method with diode-array absorbance detector and fluorescence detector for the analysis of 19 phenolic acids, flavan-3-ols, flavones, flavonols and caffeine in different types of samples was developed. Using a C₁₈ reverse-phase fused-core column separation of all compounds was achieved in less than 5 min with an overall sample-to-sample time of 10 min. Evaluation of chromatographic performance revealed excellent reproducibility, resolution, selectivity and peak symmetry. Limits of detection for all analyzed compounds ranged from 0.5 to 211 μg L⁻¹, while limits of quantitation ranged between 1.5 and 704 μg L⁻¹. The developed method was used for the determination of analytes present in different samples, including teas (black, white, green), mate, coffee, cola soft drink and an energetic drink. Concentration of the analyzed compounds occurring in the samples ranged from 0.4 to 314 mg L⁻¹. Caffeine was the analyte found in higher concentrations in all samples. Phytochemical profiles of the samples were consistent with those reported in the literature.     

Determination of Phenolic Acids and Flavones in Lonicera japonica Thumb. by Capillary Electrophoresis with Electrochemical Detection

Capillary electrophoresis with electrochemical detection (CE‐ED) was employed to analyze active ingredients of Lonicera japonica Thumb., an important crude herb frequently used in Chinese medicines. Hyperoside, chlorogenic acid, luteolin and caffeic acid are the major important active ingredients. Operating in a wall‐jet configuration, a 300 μm diameter carbon‐disk electrode was used as the working electrode, which exhibits a good response at +0.90 V (vs. saturated calomel electrode) for four analytes. Under the optimum conditions, the analytes were baseline separated within 20 min in a 50 mmol L^?1 borax buffer (pH 8.7). Notably, excellent linearity was obtained over two orders of magnitude with detection limits (S/N=3) ranging from 0.1 to 0.5 mg L^?1 for all the analytes. This method was successfully used in the analysis of Lonicera japonica Thumb. with relative simple extraction procedures, and the assay results were satisfactory.     

响应曲面法提取水松总黄酮的工艺研究

采用响应曲面法,优化了提取水松总黄酮的提取工艺条件为:微波时间3.8min,乙醇浓度69%,固液比1∶31,在此条件下,水松总黄酮的产率为1.88%。     

紫外分光光度法测定艾叶中总黄酮含量

测定波长为290nm,以柚皮素为对照品,紫外分光光度法测定了艾叶中总黄酮含量。柚皮素在1—8μg/mL具有良好的线性关系,艾叶中总黄酮含量为1.186%,平均加标回收率为101.5%。该方法简便、快捷、准确、重现性好,可作为检测艾叶中总黄酮含量的一种好方法。     

树脂吸附法分离纯化桑叶总黄酮(Ⅰ)H103树脂对桑叶水提液中总黄酮的吸附性能

采用大孔吸附树脂法从桑叶水提液中分离黄酮类化合物。通过比较10种大孔吸附树脂对桑叶水提液中总黄酮的吸附特性及机理,发现H103树脂对桑叶总黄酮吸附量大、洗脱容易、吸附速度快,是一种良好的桑叶总黄酮吸附剂。实验表明,H103树脂吸附桑叶黄酮的适宜上样浓度为6.05mg/mL,吸附动力学符合Bangham模型,吸附过程符合内扩散模型。     

树脂吸附法分离纯化桑叶总黄酮——（Ⅱ）动态法分离桑叶总黄酮的工艺条件及数学模拟

考察了H103树脂固定床吸附分离桑叶总黄酮的工艺参数,并对吸附工艺进行了数学模拟和比较.实验结果表明,H103树脂固定床吸附分离桑叶总黄酮在上样浓度6.05mg/mL时,以9mL/min上样,吸附完全后用60%乙醇以4.5mL/min流速洗脱,桑叶总黄酮产品的回收率为90.57%,纯度为76.33%,建立的固定床吸附模型为预测固定床吸附桑叶水提液中桑叶黄酮达到穿透点时间及固定床吸附容量提供了准确、快捷的方法.     

Columns and optimum gradient conditions for fast second-dimension separations in comprehensive two-dimensional liquid chromatography

Gradient elution provides significantly higher peak capacity in comparison to the isocratic elution mode, hence it is very useful in online comprehensive two-dimensional liquid chromatography (LC). We compared suitability of five commercial core-shell columns and one monolithic column for fast gradients in the second LC dimension, where the time of separation is strictly limited by the fraction cycle time. In two-dimensional reversed-phase systems with partially correlated retention, the resolution, the peak capacity, and the regularity of coverage of the second-dimension retention space can be improved by appropriate adjusting the gradient time and the gradient range to suit the sample properties. We developed a new strategy for adjusting the gradient mobile phase composition range in the second-dimension, employing the retention data of representative sample standards characterizing the sample properties, which can be calibrated using the reference alkylbenzene series. Optimized second-dimension gradients with single-step or segmented profiles covering two or more fraction ranges, employed for the separation of subsequent fractions from the first-dimension, improve significantly the resolution, the separation time, and the regularity of coverage of the two-dimensional retention plane. The approach was applied to the two-dimensional comprehensive separation of phenolic acids and flavonoid compounds occurring as natural antioxidants.