Determination of Piperazine Ferulate in Human Plasma by HPLC and Its Pharmacokinetic Study

Aim To establish a sensitive HPLC method for determination of piperazine ferulate and to study its pharmacokinetics in healthy volunteers. Methods Piperazine ferulate was separated on a Shimadzu C_ 18 column with acetic acid (0.1%)-methanol (60 ∶ 40, V/V) as mobile phase after liquid-liquid extraction, and detection was performed at 310 nm. Piperazine ferulate pharmacokinetic parameters after a single oral dose of 200 mg of piperazine ferulate dispersible tablets in 20 healthy male volunteers were calculate...

Crystal Structures, Stability, and Solubility Evaluation of a 2:1 Diosgenin-Piperazine Cocrystal

A cocrystal of diosgenin with piperazine in 2:1 stoichiometry was successfully synthesized.The solid form was prepared by liquid assisted grinding,slurry and crystallization methods.The cocrystal was characterized by powder X-ray diffraction,differential scanning calorimetry,thermogravimetric analysis,Fourier transform infrared spectroscopy,and structure determined by single crystal X-ray diffraction,the hydrogen bonds formed into fish bone structure along the[010]direction and all the molecules packed into 3D layer structure along a axis.After formation of cocrystal,the solubility of diosgenin was improved,and the solubility value in 0.2%SDS solution was approximately 1.5 times as large as that of the parent material.

Poly(ethylene glycol)-supported Piperazine——Synthesis and Application in Knoevenagel Condensation

A soluble, poly（ethylene glycol）-supported piperazine catalyst was prepared. This soluble catalyst efficiently catalyzes the Knoevenagel condensation of various aromatic aldehydes with diethyl malonate or ethyl acetoacetate in a homogeneous phase to afford the desired alkenes in good purity and yield with a facile work-up process. It was found that the polymer reagent could be repeatedly used at least four times without the too much loss of activity. The catalyst has shown a good activity, stability, and recycling capability.

Absorption Rate of CO_2 into MDEA Aqueous Solution Blended with Piperazine and Diethanolanline

Absorption rate of CO2 into aqueous solution of N-methyldiethanolamine (MDEA) blended with diethanolamine (DEA) and piperazine (PZ) was studied and a kinetic model was established. It is shown that homogeneous activation mechanism could explain this absorption process. The absorption rate coefficients of carbon dioxide into MDEA aqueous solution blended with DEA, PZ or DEA+PZ were compared with each other. The results demonstrated that the different activation effect of DEA, PZ and DEA+PZ on the carbon dioxide absorption comes from the difference in CO2 combination rate, transport of PZ and DEA to MDEA and the regeneration rate of PZ and DEA.

Novel Piperazine-based Gemini and Bola Surfactants

A series of piperazine-based Gemini and Bola surfactants were synthesized. Gemini 1 and 5 have well surface activities. Their critical micelle concentrations （cmc） is 6.47×10^-4 mol/L and 1.17×10^-3mol/L, respectively. Bola surfactants 2 and compound 3, possessing better water solubility, have lower surface activities. Calculation, carried out by MM2 energy minimization, showed that compound with more hydrophobic chains in a spacer of limited length is difficult to be synthesized.

Design,synthesis and biological estimation of 1-(benzoxazole-2-yl)piperazine and 4-(benzoxazole-2-yl)piperidine derivatives as potentialα_1-AR antagonists

Two series of 1-（benzoxazole-2-yl）piperazine （Sa-i） and 4-（benzoxazole-2-yl）piperidine compounds （10a-i） were designed, synthesized and evaluated for their α1-AR antagonistic activities. Biological assay in vitro indicated that 10h showed slightly stronger α1-AR antagonistic activity to that of our lead compound 1.

Rapid analysis of piperazine ferulate tablets by optic-fiber sensing technology and the similarity of ultraviolet spectra

A rapid analysis method of piperazine ferulate tablets by optic-fiber sensing technology with UV-vis absorption spectrum was established. Qualitative and quantitative data were obtained and compared by maximum and minimum wavelength, absorbance and contrast spectra. Similarity method was used to identify authenticity of drugs. The difference of contents measured by this method and UV determination method in China Pharmacopoeia showed no statistical significance (P40.05), while the similarity can be used as a parameter to identify the authenticity of drugs.

Phase Transfer Catalyzed Synthesis and Antibacterial Activity of Water-soluble S-Triazolo[3,4-b][1,3,4]thiadiazoles Containing Piperazine Group

6/3-（4-Chlorophenyl）-s-triazolo[3, 4-b][1, 3, 4]thiadiazoles （2,a-e） and （Sa-e） were synthesized respectively by intermolecular cyclization of 5-aryl / 4-chlorophenyl-4-amino-3- mercapto-1, 2, 4-triazoles （la-e） and （4） with 4-chlorobenzoic acid / aryl acids, which were condensed with piperazine under phase transfer catalyst TBAB to yield the corresponding free bases of monopiperazine derivatives and followed to form water-soluble salts （3a-e） and （6a-e） with hydrochloric acid in good yields. The in vitro biological results showed that piperazine group conjugated with the above fused heterocycles played an important role in antibacterial activity. The structures of novel compounds were confirmed by IR, ＇H NMR, MS and elemental analysis.

Microwave-assisted synthesis of new N^4-[bi-(4-fluorophenyl)-methyl]-piperazine thiosemicarbazones under solvent-free conditions

Six new N4-[bi-（4-fluorophenyl）-methyl]-piperazine thiosemicarbazones 3a-f have been prepared starting from [bi-（4-fluorophenyl）-methyl]-piperazine in solvent-free condition under microwave irradiation with excellent yields. Their structures have been determined by elemental analysis, IR, MS and 1H NMR data.

Experimental studies and artificial neural network modeling of surface tension of aqueous sodium L-prolinate solutions and piperazine blends

The surface tension study is very crucial for the design of CO2 gas absorption contacting equipment. The significance of the surface tension has been increasing due to its consideration in various technological fields. This property influences the mass transfer and hydrodynamics of gas absorption systems, mainly multiphase systems, in which the interface between gas and liquid exists. Therefore, in this study, surface tension of aqueous solutions of sodium L-prolinate(SP) and piperazine(PZ) blends were measured at ten different temperatures from(298.15 to 343.15) K. The SP mass fractions were 0.10, 0.20, and 0.30;while the mass fractions of PZ were 0.02 and 0.05. The experimental results showed that the surface tension increase with increasing the mass fractions of SP and PZ in aqueous blends, and decrease linearly with rising temperature. The experimental data of surface tension were correlated by two empirical correlations as a function of temperature and mass fractions for estimating the predicted data using the optimized correlation coefficients. Moreover, the modeling of surface tension data was carried out using Artificial Neural Network(ANN) approach. The results obtianed from ANN modeling were compared with applied empirical correlation. It was found that the ANN approach outperformed the empirical correlation used in this study. Besides, a quantitative analysis of variation(ANOVA) was performed in order to determine the significance of data. The surface tension of aqueous SP and SP + PZ was also compared with various conventional solvents.

Influence of pretreatment of piperazine ferulate on pharmacokinetic parameters of methotrexate in methotrexate-induced renal injury model rats by HPLC-MS

The present study was designed to investigate the influence of the pretreatment of piperazine ferulate on pharmacokinetic parameters of methotrexate in methotrexate-induced renal injury rats.A simple and efficient high performance liquid chromatography coupled with mass spectrometry(HPLC-MS)method was developed to determine methotrexate in rat plasma.Methotrexate and syringic acid(internal standard)were extracted from rat plasma samples by protein precipitation with acetonitrile.The analysis was performed on a CAPCELL PAK C18column(150 mm×4.6 mm,5μm)with acetonitrile and 5 mmol/l ammonium acetate aqueous(10:90,v/v).The linear range was 5.0×10-2to 100.0μg/ml for methotrexate.Other parameters were all within the acceptance criteria.The validated method was successfully applied the pharmacokinetic study of methotrexate between two methotrexate treated groups(with and without the pretreatment of piperazine ferulate).Compared with the methotrexate treated alone group,the pharmacokinetic parameters in the methotrexate with the pretreatment of piperazine ferulate group showed significantly lower MRT(0-t),MRT(0-∞) and T1/2.Results suggested that methotrexate can be rapidly eliminated,cleared or metabolized in rat blood,which might be related to the pretreatment of piperazine ferulate.The method provided deeper insights into rational clinical use of methotrexate with the pretreatment of piperazine ferulate on cancer patients with renal dysfunction.

Synthesis of Novel Non-Nucleoside HIV-1 Reverse Transcriptase Inhibitors-1-(3-Phthalimido-2-oxobutyl)-4-Substituted-phenylpiperazines

We have designed and synthesized a series of new phthalimidopiperazines, biological activity test show that the target compounds(Ic, Ie, ii) can inhibit HIV-I RT with IC50 20.0, 43.8, and 63.7 mu M, respectively.

The 1:2 Complex of Piperazine with Some Phenols:Hydrogen Bonding Pattern Involved in Transition States in Solution

A novel model for the 1: 2 complex of piperazine with some phenols in solution is established and verified. In CDCl3 solution, one piperazine molecule is tied to two phenol molecules by hydrogen bonds of O-H---N and N-H---O. And the protons of >NH and -OH groups exchange quickly and simultaneously between the atoms of phenol oxygen and piperazine nitrogen.

An Efficient Process for Preparing 4-Methyl-2-phenyl Piperazine Hydrochloride and its Derivatives

An improved method for preparation of 4-methyl-2-phenyl piperazine and its derivatives with higher yield and inexpensive reagents was developed, the products were characterized by 1H-NMR and MS.

Syntheses, Structures and Fluorescent Property of Two Cd(Ⅱ) 3D Coordination Polymers with Mixed Ligands of Azide and Piperazine Derivatives

Two new coordination polymers, [Cd（N3）2（Baep）l/2]n （1） and [Cd2（N3）4（CH3OH）（Bapp）I/.2]n （2） （Baep = 1,4-bis（2-aminoethyl）piperazine, Bapp = 1,4-bis（3-aminopropyl）piperazine） were synthesized. The crystal of 1 is of monoclinic system, space group P21/c with a = 9.341（7）, b = 11.677（9）, c = 8.195（6） A, fl = 93.925（13）, V= 891.8（11） A3, Z= 4, μ（MoKa） = 2.42 mm-1, Mr = 280.58, Dc = 2.090 g/cm3, the final R = 0.0297 and wR = 0.0720. The crystal of 2 is of triclinic system, space group PI with a = 9.121（5）, b = 9.666（5）, c = 10.250（6） A, a = 72.91（2）, β= 77.10（2）, V = 73.95（2）°, V = 820.0（8）°, Z = 2,μ（MoKa） = 2.62 mm-1, Mr= 522.10, Dc = 2.114 g/cm3, the final R = 0.0251 and wR = 0.0632. Single-crystal X-ray diffraction studies reveal that 1 is a 3D structure based on a dinuclear unit {Cd2（N3）a（Baep）}, in which the Baep ligands formed in situ display two different bridging modes. Compound 2 also has a 3D structure based on a tetranuclear cluster {Cda（N3）8（CH3OH）2（Bapp）}, in which the azido anions exhibit four different bridging modes （μ-1,1, μ-1,3, μ-l,l,1 and μ-1,1,3）. The thermal stability and fluorescent property of 1 and 2 have also been investigated.

SYNTHESIS OF 1－（2－AMINOETHYL） PIPERAZINE RESIN AND ITS ADSORBABILITYFOR NOBLE METALLIC IONS

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Construction of One New 3D Zinc-organic Framework Based on D-(+)-camphoric Acid and Bis(4-pyridylmethyl)piperazine

A new polymer [Zn2（cam）2（bpmp）]n 1 （H2cam = D-（＋）-camphoric acid, bpmp = bis（4-pyridylmethyl）piperazine） was synthesized under hydrothermal conditions. The compound crystallizes in the monoclinic system, space group P21/n with a = 12.305（9）, b = 12.945（9）, c = 13.619（10） A, β = 116.833（8）°, V= 1936（2）A3, Z = 4, Mr = 397.76, Dc= 1.365 Mg/m3,μ = 1.292 mm-1, F（000） = 832, the final R = 0.0578 and wR = 0.1678 for 2838 observed reflections with I 〉 2σ（I）. The compound presents a three-dimensional （3D） network extended by homochiral 2D layer and bpmp ligands. From the topology point of view, the structure could be described as a 3D 6-connected mab net with （44.610.8） topology. In addition, infrared spectroscopy, elemental analyses, thermogravimetric analysis and powder X-ray diffraction properties of 1 are also investigated.

Kinetic and Mechanistic Study of Oxidation of Piperazines by Bromamine-T in Acidic Medium

Oxidations of piperazine, 1-methylpiperazine and 1-ethylpiperazine by bromamine-T (BAT) in buffered acidic medium have been kinetically studied at 303 K. The reaction shows a first-order dependence of the rate each on [BAT]0 and [piperazine]0, and an inverse fractional-order dependence on [H+]. The additions of halide ions and the reduction product of BAT, p-toluenesulfonamide, have no effect on the reaction rate. The variation of ionic strength of the solvent medium has no influence on the rate. Activation parameters have been evaluated from the Arrhenius and Eyring plots. A common mechanism consistent with the kinetic data has been proposed for all piperazines. The protonation constants of substrates have been evaluated. The Hammett linear free-energy relationship has been observed for the reaction with ρ = ?0.5 indicating that the electron-donating groups enhance the reaction rate by stabilizing the transition state. An isokinetic relationship observed shows β = 368 K indicating the dominance of enthalpy factors on the reaction rate.

Structural Characterization and Proton-conductive Property of a Lanthanide Metal-organic Framework Assembled from 1,2,4,5-Benzenetetracarboxylic Acid and Piperazine

The reaction of Pr（Ⅲ） salt with 1,2,4,5-benzenetetracarboxylic acid（H4betc） and piperazine（pip） yielded a lanthanide metal-organic framework {[Pr（betc）（H2O）2]（H2pip）0.5}n（1）under hydrothermal conditions. Compound 1 was characterized by single-crystal X-ray structural analysis, elemental analysis, IR, X-ray powder diffraction, and thermal gravimetric. Compound 1crystallizes in monoclinic, space group P21/n with a = 11.023（5）, b = 11.109（5）, c = 11.456（5） A, β = 110.065（5）°, V = 1317.7（9） A3, Mr = 471.14, Z = 4, F（000） = 920, Dc = 2.375 g/cm^3, μ（Mo Kα） = 3.761 mm-1, the final R = 0.0286 and w R = 0.0821（I 〉 2σ（I））. Compound 1 exhibits a 2D network with（4, 4） topology, and a 3D supramolecular framework formed by hydrogen-bonding interactions. The proton conductivity of compound 1 has been investigated at ~97% relative humidity and different temperature.