Micelle to trapping solution stacking in micellar electrokinetic chromatography

An analytical strategy micelle to trapping solution stacking (MSS) was developed in acidic buffer in micellar electrokinetic chromatography (MEKC). The stacking mechanism is based on the transport, release, capturing of molecules bound to micelle carriers that are made to collapse into trapping solution (TS) to serve as the medium to contain and stacking the analytes. Tetrandrine and fangchinoline were selected as model mixture using sodium dodecyl sulfate (SDS) micelles as carrier to demonstrate this stacking method. The experiments by MSS-MEKC were carried out and further compared with those by normal MEKC. The results reveal that 113–123-fold improvements in the detection sensitivity was obtained for the analytes, and separation and determination of tetrandrine and fangchinoline in Stephaniae tetrandrae S. Moore and Fengtongan capsules were finished under optimum conditions using the sample matrix containing 8.0 mM SDS and TS containing 50 mM H₃PO₄–55% (v/v) ethanol.     

Ultra high performance liquid chromatography with tandem mass spectrometry method for the determination of tetrandrine and fangchinoline in rat plasma after oral administration of Fangji Huangqi Tang and Stephania tetrandra S. Moore extracts

A rapid, sensitive, and reliable analytical method based on ultra high performance liquid chromatography with tandem mass spectrometry has been developed for the simultaneous determination of fangchinoline and tetrandrine in rat plasma. Plasma samples were pretreated by protein precipitation with acetonitrile. The analysis was performed on a C₁₈ reversed‐phase ultra high performance liquid chromatography column (2.1 mm × 100 mm, 3.5 μm, Agilent), and the flow rate was set at 0.4 mL/min. Under the experimental conditions, extraction recoveries from plasma were 68.1–72.8% for fangchinoline and 69.2–76.5% for tetrandrine. The plasma concentrations of tetrandrine and fangchinoline in rats at assigned time points were all successfully detected through exactly validated method. Good linearities were obtained in the range of 0.92–184 ng/mL for tetrandrine and in the range of 0.83–166 ng/mL for fangchinoline. The intra‐ and interday precisions for both analytes were within 11.1% and the accuracies were within the range of –10.7 to 11.3%. The developed method was then successfully applied to investigate the pharmacokinetic properties of these two alkaloids after oral administration of Stephania tetrandra S. Moore extracts and Fangji Huangqi Tang. The comparative results provided a meaningful basis for a better understanding of the practical value of the compatibility theory of traditional Chinese medicine in the clinic.     

Syntheses and Anti-cancer Activities of Derivatives of Tetrandrine and Fangchinoline

A series of derivatives of tetrandrine and fangchinoline was designed and synthesized to find more active anti-cancer compounds. Their anti-cancer activities were tested against human hcpatocellular carcinoma BEL-7402 and PLC/PRF/5 cells, human lung adenocarcinoma A549 cells as well as human leukaemia K562 cells, and the structure-activity relationship（SAR） was also studied. All the compounds except BI exhibited superior inhibitory ac- tivities against PLC/PRF/5 cells with half maximal inhibitory conccntration（ICs0） values of less than 15 μmol/L, and compounds A2, A4, B2 and B4 showed IC50 values of less than 9 pmol/L. Compounds A2, A6, B2 and B4 showed potent anti-cancer activities against all the tested cells with 1C5o values of less than 10 pmol/L. The results show that terandrine and fangchinoline derivatives are potential suppressors to human cancer.     

Online concentration by field-amplified sample injection in acidic buffer for analysis of fangchinoline and tetrandrine in herbal medicine by flow injection-micellar electrokinetic capillary chromatography

A novel, rapid, and continuous online concentration approach based on field-amplified sample injection for the analysis of fangchinoline and tetrandrine was developed in this paper by combination of flow injection-MEKC. The BGE used was a solution composed of 75 mM H3PO4-triethylamine-2.5% v/v polyoxyethylene sorbitan monolaurate-20% v/v methanol buffer (pH* 5.0). The analytes prepared in 50% v/v aqueous ethanol were used as the test analytes. Sample was injected electrokinetically between plugs of water. When the cations reached the boundary between the water plug and BGE, they slowed down and became concentrated. Thereafter, MEKC was initiated for the separation. This results in 6.8-8.9-fold improvement in concentration sensitivity relative to conventional CE methods. The separation could be achieved within 10 min and sample throughput rate can reach up to 50/h. The repeatability (defined as RSD) was 4.8, 4.4% with peak height evaluation and 3.6, 0.94% with peak area evaluation for TET and FAN, respectively.     

Application of nonaqueous capillary electrophoresis for quantitative analysis of quinolizidine alkaloids in Chinese herbs

An easy, rapid method for simultaneous determination of tetrandrine (TET), fangchinoline (FAN), sinomenine (SIN) and tetrahydropalmatine (TEP) in Chinese herbs was developed by nonaqueous capillary electrophoresis without pretreatment for the first time. Optimum separation was achieved with a fused-silica capillary column ( i.d.) and a running buffer containing 50 mM ammonium acetate, 1.0% acetic acid and 20% acetonitrile in methanol medium. The applied voltage was 20.0 kV. The analytes were detected by UV at 214 nm. The effects of concentration of ammonium acetate, acetic acid and organic modifier on electrophoretic behavior of the analytes were studied. Regression equations revealed linear relationships (correlation coefficients: 0.9991-0.9999) between the peak area of each analyte and the concentration. The levels of analytes in Stephania tetrandra S. Moore, Rhizoma corydalis and Sinomenium acutum Rehd. et. Wils were easily determined with recoveries ranging from 96 to 107%.     

Study of the Interaction of Fangchinoline with Human Serum Albumin by Fluorescence and UV Spectroscopic Method

The interaction of fangchinoline with human serum albumin (HSA) was studied by use of fluorescence quenching spectra, synchronous fluorescence spectra, and ultraviolet spectra. It was shown that fangchinoline has a strong ability to quench the fluorescence of HSA. The Stern‐Volmer curves based on the quenching of the fluorescence of HSA by fangchinoline indicated that the quenching mechanism of fangchinoline on HSA was static quenching and non‐radiation energy transfer. Based on the Förster theory of non‐radiation energy transfer, the binding distances (r) and the binding constants (K _A) between fangchinoline and HSA were found. The thermodynamic parameters obtained revealed that the interaction between fangchinoline and HSA was mainly driven by hydrophobic force. The conformational changes of HSA were investigated by use of synchronous fluorescence. The result indicates that an ionic electrostatic interaction between fangchinoline and HSA could not be excluded.     

Ionic liquid‐based ultrasound‐assisted extraction of fangchinoline and tetrandrine from Stephaniae tetrandrae

An ionic liquid‐based ultrasound‐assisted extraction method has been developed for the effective extraction of fangchinoline and tetrandrine from Stephaniae tetrandrae. The effects of some ultrasound‐assisted extraction parameters including the concentration of [BMIM][BF₄], pH, ultrasonic power and time were investigated to optimize the ultrasound‐assisted extraction conditions. Compared to the regular ultrasound‐assisted extraction and traditional refluent extraction, the proposed [BMIM][BF₄]‐based ultrasound‐assisted extraction offered shorter extraction times (from 6 h to 40 min) and remarkable higher efficiencies (approximately 30% improved), which supported the suitability of the proposed approach. In addition, the proposed approach was confirmed by the good correlation coefficient (R²), recovery and reproducibility (RSD, n = 5), which were in the range of 0.9992–0.9995, 85.5–101.1%, and 1.87–4.33%, respectively.     

防己诺林碱与牛血清白蛋白相互作用的研究

在不同温度下,用荧光猝灭光谱、同步荧光光谱和紫外-可见吸收光谱,研究了防己诺林碱与BSA相互作用的光谱学行为。防己诺林碱对BSA有较强的荧光猝灭作用。根据不同温度下防己诺林碱对BSA的荧光猝灭作用,利用Stern-Volmer方程处理实验数据,表明防己诺林碱对BSA的荧光猝灭作用属于静态猝灭。根据Frster非辐射能量转移理论计算出了防己诺林碱与BSA间的结合距离R(27 ℃ 2.51 nm; 37 ℃ 2.72 nm; 47℃ 2.89 nm)、结合常数K_A(27 ℃ 1.05×105 L·mol-1; 37 ℃ 3.31×105 L·mol-1; 47 ℃ 7.24×105 L·mol-1)及对应温度下的热力学参数。热力学数据表明二者主要靠疏水作用力结合,同时用同步荧光光谱探讨了防己诺林碱对BSA构象的影响。     

电喷雾质谱法研究防己诺林碱与G-四链体的相互作用

采用电喷雾质谱法研究了防己诺林碱与双链核酸及G-四链体的相互作用. 结果表明, 防己诺林碱可选择性地与G-四链体结合. 利用串联质谱技术对防己诺林碱与核酸的结合模式进行了研究, 结果表明, 防己诺林碱可能通过末端堆积作用与G-四链体结合, 而通过插入作用与双链核酸结合. 结合模式的差异导致防己诺林碱选择性地与G-四链体结合.