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排序方式: 共有90条查询结果,搜索用时 15 毫秒
1.
Zhu XQ Cao L Liu Y Yang Y Lu JY Wang JS Cheng JP 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(16):3937-3945
Five 1-(p-substituted phenyl)-1,4-dihydronicotinamides (GPNAH-1,4-H(2)) and five 1-(p-substituted phenyl)-1,2-dihydronicotinamides (GPNAH-1,2-H(2)) were synthesized, which were used to mimic NAD(P)H coenzyme and its 1,2-dihydroisomer reductions, respectively. When the 1,4-dihydropyridine (GPNAH-1,4-H(2)) and the 1,2-dihydroisomer (GPNAH-1,2-H(2)) were treated with p-trifluoromethylbenzylidenemalononitrile (S) as a hydride acceptor, both reactions gave the same products: pyridinium derivative (GPNA(+)) and carbanion SH(-) by a hydride one-step transfer. Thermodynamic analysis on the two reactions shows that the hydride transfer from the 1,2-dihydropyridine is much more favorable than the hydride transfer from the corresponding 1,4-dihydroisomer, but the kinetic examination displays that the former reaction is remarkably slower than the latter reaction, which is mainly due to much more negative activation entropy for the former reaction. When the formed pyridinium derivative (GPNA(+)) was treated with SH(-), the major reduced product was the corresponding 1,4-dihydropyridine along with a trace of the 1,2-dihydroisomer. Thermodynamic and kinetic analyses on the hydride transfer from SH(-) to GPNA(+) all suggest that the 4-position on the pyridinium ring in GPNA(+) is much easier to accept the hydride than the 2-position, which indicates that when the 1,4-dihydropyridine is used the hydride donor to react with S, the formed pyridinium derivative GPNA(+) may return to the 1,4-dihydropyridine by a hydride transfer cycle; but when the 1,2-dihydropyridine is used as the hydride donor, the formed pyridinium derivative can not return to the 1,2-dihydropyridine by the hydride reverse transfer from SH(-) to GPNA(+). These results clearly show that the hydride-transfer cycle is favorable for the 1,4-dihydronicotinamides, but unfavorable for the corresponding 1,2-dihydroisomers. 相似文献
2.
Daqing Wang Baoxue Zhou Yuanjang Jia Feng Shi Yiping Fan 《Journal of Thermal Analysis and Calorimetry》1995,45(1-2):221-226
The complex Mn(Nica)2Cl2 (Nica=nicotinamide) was prepared, and its decomposition was studied by means of TG and DSC. The IR spectra of the products
of thermal decomposition were examined at every stage. Kinetic analysis of the first stage of thermal decomposition was performed
via the TG-DTG curves, and the kinetic parameters were obtained from analysis of the TG-DTG curves with integral and differential
methods. The most probable kinetic function was suggested from a comparison of the kinetic parameters. Mathematical expressions
were derived for the kinetic compensation effect.
Zusammenfassung Der Komplex Mn(Nica)2Cl2 (Nica steht für Nikotinamid) wurde hergestellt und seine Zersetzung mittels TG und DSC untersucht. Die thermisch zersetzten Substanzen jedes Schrittes wurden mittels IR-Spektren untersucht. Anhand der TG-DTG-Kurven erstellte man eine kinetische Analyse des ersten Schrittes der thermischen Zersetzung, die kinetischen Parameter wurden aus den TG-DTG-Kurven unter Einsatz von Integrations- und Differentialmethoden ermittelt. Durch Vergleich der kinetischen Parameter wurde die wahrscheinlichste kinetische Funktion vorgeschlagen. Mathematische Ausdrücke für den kinetischen Kompensationseffekt wurden erhalten.相似文献
3.
Icbudak H. Heren Z. Kose D. Ali Necefoglu H. 《Journal of Thermal Analysis and Calorimetry》2004,76(3):837-851
The mixed-ligand p-hydroxybenzoate complexes of Ni(II), Cu(II) and Zn(II) with nicotinamide and N,N-diethylnicotinamide were synthesized and
characterized by elemental analysis, magnetic susceptibility measurements and mass spectrometry. The thermal behavior of the
complexes was studied by simultaneous TG, DTG and DTA methods in static air atmosphere. The infrared spectral characteristics
of the complexes are also discussed. The complexes contain two water molecules, two p-hydroxybenzoato (p-hba) and two nicotinamide (na) (or diethylnicotinamide (dena)) ligands per formula unit. In these complexes,
all ligands are coordinated to the metal ion as monodendate ligands. In Zn(II)-na and Cu(II)-dena complexes, thep-hydroxybenzoate behaves as bidentate chelating ligand through carboxylic oxygen atoms. The decomposition pathways and the
stability of the complexes are interpreted in the terms of the structural data. The final decomposition products were found
to be the respective metal oxides.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
A strain ofRhodococcus equi SHB-121 forming 3-cyanopyridine hydratase was screened from nitrile-polluted soil. The optimum conditions for the formation
of 3-cyanopyridine hydratase by the strain SHB-121 have been studied. Under the optimum conditions, the specific activity
of the enzyme reached 5.32 U/mg of dry cell, 95 times higher than that cultured in screening medium. In addition, the activity
of coexistent amidase was very low.
3-Cyanopyridine hydratase was purified from methylacrylamide-induced cells ofRh. equi SHB-121 by procedures including ultrasonic oscillation, ammonium sulfate precipitation, and column chromatographies on DEAE-cellulose
DE52, hydroxyapatite, and Sephadex G-25. The overall purification was 31-fold. The molecular weight of the enzyme was about
30 kDA by SDS-PAGE. The pI value was 4.1. The transition temperature and pH were 7.0°C and 6.0, respectively, resulting from
the differential spectra.
The optimum pH and temperature for the enzyme reaction were 8.0 and 30°C. The enzyme activity was strongly inhibited by Ag+, Hg2+, Cu2+, and NH4
+, whereas it was enhanced by Fe3+ slightly. The enzyme catalyzed the hydration of 3-cyanopyridine to nicotinamide, and itsKm value was 0.1 mol/L. Uncompetitive inhibitor sodium cyanide has a K, value of 5 mmol/L. 相似文献
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8.
报道一种新型1,2,4-噁二唑衍生物,N-[2,6-二氯-4-(1,2,4-噁二唑-3-基)苯基]-2-甲氧基烟酰胺(C15H10Cl2N4O3)的合成,其结构通过1H NMR、13C NMR、HRMS以及X-射线单晶衍射进行表征。该晶体结构属于三斜晶系, P 1(—) 空间群,晶胞参数 a = 7.1291 (9), b = 8.4352 (10), c = 14.0021 (18) ?, α = 73.834 (3), β = 77.407 (3), γ = 70.019 (3)°, Mr = 366.18, V = 752.97 (16) ?3, Z = 2, Dc = 1.611 g/cm3, μ(MoKα) = 0.454 mm-1, F(000) = 372.0 , 晶体尺寸为 0.36 × 0.2 × 0.1 mm,Rint = 0.023。初步活性研究发现,该化合物对LoVo, A549, SK-BR-3, HeLa这四种肿瘤细胞株具有明显的抑制作用,尤其是对HeLa细胞的抑制活性与阳性药物5-氟尿嘧啶 (5-FU)相当。 相似文献
9.
搭建了微流控芯片简易安培检测器,并用于市售药品烟酰胺片中烟酰胺含量的测定。由碳纳米管微圆盘电极和钛管组成集成双电极,中间的碳纳米管微圆盘电极作为安培检测的工作电极,外套的钛管既作为安培检测的对极,又充当分离高压电源的地极,使其结构更加简化和微型化。优化了缓冲溶液种类、浓度,分离电压及进样时间等实验条件。结果表明,在10 mmol·L-1磷酸盐缓冲液(pH 7.8)中,进样10 s,在2.0kV电压下分离,烟酰胺在2 min内可实现较好的分离和检测,其线性范围为10~600μmol·L-1,检出限(S/N=3)为5.0μmol·L-1,相对标准偏差(RSD)为3.0%,平均加标回收率为99.1%。该装置实现了微型化和集成化,并具有检测灵敏度较高、选择性好、成本低等特点,可用于药品的质量控制。 相似文献
10.
Divakar Vishwanath Swamy S. Girimanchanaika Dukanya Dukanya Shobith Rangappa Ji-Rui Yang Vijay Pandey Peter E. Lobie Basappa Basappa 《Molecules (Basel, Switzerland)》2022,27(3)
Novel PARP inhibitors with selective mode-of-action have been approved for clinical use. Herein, oxadiazole based ligands that are predicted to target PARP-1 have been synthesized and screened for the loss of cell viability in mammary carcinoma cells, wherein seven compounds were observed to possess significant IC50 values in the range of 1.4 to 25 µM. Furthermore, compound 5u, inhibited the viability of MCF-7 cells with an IC50 value of 1.4µM, when compared to Olaparib (IC50 = 3.2 µM). Compound 5s also decreased cell viability in MCF-7 and MDA-MB-231 cells with IC50 values of 15.3 and 19.2 µM, respectively. Treatment of MCF-7 cells with compounds 5u and 5s produced PARP cleavage, H2AX phosphorylation and CASPASE-3 activation comparable to that observed with Olaparib. Compounds 5u and 5s also decreased foci-formation and 3D Matrigel growth of MCF-7 cells equivalent to or greater than that observed with Olaparib. Finally, in silico analysis demonstrated binding of compound 5s towardsthe catalytic site of PARP-1, indicating that these novel oxadiazoles synthesized herein may serve as exemplars for the development of new therapeutics in cancer. 相似文献