1.Preparation and Characterization of a Novel Isatin Derivative of β-Cyclodextrin-bonded SBA-15 Stationary Phase for HPLC
Yang ZHANG ; Laisheng LI ; Biaoping CHEN ; Rendan ZHOU ; Guizhen NIE
Chinese Journal of Analytical Chemistry 2014;(3):375-383
An isatin derivative ofβ-cyclodextrin Schiff base was first synthesized by the condensation reaction between the carbonyl group of isatin and ethylenediamino group of the mono-substituted β-cyclodextrin. The Schiff base ligand was chemically linked to homemade ordered mesoporous SBA-15 silica gel via 3-( triethoxysilyl) propyl isocyanate coupling agent. In this way, a novel isatin derivative of β-cyclodextrin-bonded SBA-15 stationary phase ( ISCDP) was prepared for HPLC. Its chemical and physical parameters were characterized by infrared spectroscopy, mass spectroscopy, elemental analysis, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and BET specific surface area analysis. The basic chromatographic property of ISCDP was evaluated by using polar halogenated uracils and disubstituted benzene positional isomers as solute probes in reversed-phase chromatography. ISCDP was also used to enantioseparate twoβ-blocker drugs in polar organic mode and two dansyl amino acids in reversed-phase mode, respectively. The related chromatographic separation mechanism was also discussed. Above studies were expected to provide experimental basis for the practical application of ISCDP in the future. The results showed that the introduction of isatin indole ring could enhanced the reversed-phase chromatographic separation ability of ISCDP for halogenated uracils within 7 min. The new packing also exhibited high stereoselectivity for the position isomers of nitroaniline, aminophenol and benzenediol, in which the para isomers were finally eluted due to strong inclusion interaction between the isatin derivative of β-cyclodextrin ligand and the isomers. Meanwhile, the introduction of isatin indole ring could also improve the chiral separation ability of ISCDP. For example the fast enantioseparations of chiral β-adrenergic blockers and dansyl-amino acids on ISCDP were achieved within 20 min (Rs>1. 3). Obviously, besides hydrophobicity, various synergistic interactions could enhance the separation selectivities of the new stationary phase for chiral and achiral analytes, including dipole-dipole, hydrogen bonding,π-π and inclusion interactions. The ordered pore structure of SBA-15 facilitated to fast and efficient separation and analysis for drugs with good permeability and low mass transfer resistance.
2.Enantioseparation and Determination of Propranolol in Human Plasma on a New Derivatized β-Cyclodextrin Bonded Phase by HPLC
Rendan ZHOU ; Laisheng LI ; Biaoping CHENG ; Guizhen NIE ; Hongfu ZHANG
Chinese Journal of Analytical Chemistry 2014;(7):1002-1009
A 6-azido-β-cyclodextrin was synthesized and derivatized with p-nitrophenyl isocyanate as chiral ligand. Following that the ligand was chemically bonded to mesoporous SBA-15 via a ‘Click Chemistry ’ reaction of the azido group with alkynyl group. A new p-nitrophenylcarbamoylatedβ-cyclodextrin bonded SBA-15 chiral stationary phase ( NPCSP ) for HPLC was obtained. The new stationary phase was first used to enantioseparate propranolol in human plasma under the polar organic solvent mode. The effects of methanol content , additive concentration of glacial acetic acid/triethylamine in mobile phase and the temperature on the enantioseparation were studied. The optimal chromatographic conditions were as follows: mobile phase was acetonitrile/methanol/glacial acetic acid/triethylamine (90:10:1. 25:2. 25, V/V), temperature 288 K, flow rate of 0. 5 mL/min, injection volume of 20 μL, detection wavelength at 290 nm. The resolution was 2. 04 with a short run time (< 15 min) under the above conditions. The composition of propranolol in plasma was quantitatively measured by HPLC-MS selected ion monitoring mode ( [ M +H ]+ m/z 260 . 10 ) with hydrochlorothiazide as internal standard. And linear range was 2. 5-250 μg/L and with a good linear relationship. The detection limit was 1 μg/L according to S/N=3. The experimental results showed that the chiral stationary phase exhibited excellent chiral separation ability to propranolol and the analysis method for propranolol in plasma was sensitive, accurate, simple and fast, which could be used for the determination of propranolol in plasma and pharmacokinetic studies.
3.The study of inhibit the Slit/Robo pathway on vascular restenosis after angioplasty in rabbits
Zhihuan ZENG ; Rendan ZHANG ; Yanqun ZHAO ; Jianyi ZHENG ; Wanxing ZHOU ; Wei ZHANG ; Guiping ZHU ; Bowei LI
The Journal of Practical Medicine 2016;32(12):1934-1937
Objective To study the effect and mechanism of down-regulating Silt2/Robo 1 signaling pathway on rabbit iliac artery after angioplasty restenosis. Methods The 30 male New Zealand white rabbits were divided randomly into 3 groups , namely the blank group , the control group , and the experimental group , 10 rabbits in each group. Hign-fat feeding , the rabbits were produced endothelial denudation of iliac artery stenosis model. Another 4 weeks of feeding , percutaneous balloon angioplasty was performed. Then R5 antibody was injected into the abdominal cavity. After 4 weeks of feeding ,angiography again. The results of angiography was analysied by image workstation. The concentrations of Slit2 and Robo1 was detected by ELISA. The iliac artery tissue examined by HE staining. Results The rabbit iliac artery after angioplasty restenosis animal model was set up successfully. Compared with the control group and the experimental group , the serum concentration of Slit2 and Robo1 were significantly higher (P < 0.01) than the blank group. But in the experimental group, the Slit2 and Robo1 serum concentrations were significantly lower than those in the control group (P < 0.05) after R5 antibody intervention. The area ratio stenosis and diameter stenosis rate of iliac artery were reduced that confirmed by angiography. Conclusion The expression of Slit2/Robo1 was significantly higher in the rabbit model of vascular restenosis. R5 antibody can effectively inhibit the expression of Slit2/Robo1. Down regulation of Slit2/Robo1 signaling pathway in the treatment of restenosis after angioplasty in rabbits.