New Charge Transfer Complexes of K+-Channel-Blocker Drug (Amifampridine; AMFP) for Sensitive Detection; Solution Investigations and DFT Studies

UV–Vis spectroscopy was used to investigate two new charge transfer (CT) complexes formed between the K⁺-channel-blocker amifampridine (AMFP) drug and the two π-acceptors 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) and tetracyanoethylene (TCNE) in different solvents. The molecular composition of the new CT complexes was estimated using the continuous variations method and found to be 1:1 for both complexes. The formed CT complexes’ electronic spectra data were further employed for calculating the formation constants (K_CT), molar extinction coefficients (ε_CT), and physical parameters at various temperatures, and the results demonstrated the high stability of both complexes. In addition, sensitive spectrophotometric methods for quantifying AMFP in its pure form were proposed and statistically validated. Furthermore, DFT calculations were used to predict the molecular structures of AMFP–DDQ and AMFP–TCNE complexes in CHCl₃. TD-DFT calculations were also used to predict the electronic spectra of both complexes. A CT-based transition band (exp. 399 and 417 nm) for the AMFP–TCNE complex was calculated at 411.5 nm (f = 0.105, HOMO-1 → LUMO). The two absorption bands at 459 nm (calc. 426.9 nm, f = 0.054) and 584 nm (calc. 628.1 nm, f = 0.111) of the AMFP–DDQ complex were theoretically assigned to HOMO-1 → LUMO and HOMO → LUMO excitations, respectively.     

Synthesis, crystal structure, quantum chemical calculations, DNA interactions, and antimicrobial activity of [Ag(2-amino-3-methylpyridine)(2)]NO(3) and [Ag(pyridine-2-carboxaldoxime)NO(3)

[Ag(2-amino-3-methylpyridine)(2)]NO(3) (1) and [Ag(pyridine-2-carboxaldoxime)NO(3)] (2) were prepared from corresponding ligands and AgNO(3) in water/ethanol solutions, and the products were characterized by IR, elemental analysis, NMR, and TGA. The X-ray crystal structures of the two compounds show that the geometry around the silver(I) ion is bent for complex 1 with nitrate as an anion and trigonal planar for complex 2 with nitrate coordinated. ESI-MS results of solutions of 2 indicate the independent existence in solution of the [Ag(pyridine-2-carboxaldoxime)](+) ion. The geometries of the complexes are well described by DFT calculations using the ZORA relativistic approach. The compounds were tested against 14 different clinically isolated and four ATCC standard bacteria and yeasts and also compared with 17 commonly used antibiotics. Both 1 and 2 exhibited considerable activity against S. lutea , M. lutea , and S. aureus and against the yeast Candida albicans , while 2-amino-3-methylpyridine is slightly active and pyridine-2-carboxaldoxime shows no antimicrobial activity. In addition, the interaction of these metal complexes with DNA was investigated. Both 1 and 2 bind to DNA and reduce its electrophoretic mobility with different patterns of migration, while the ligands themselves induce no change.     

Structural study of 2-(1-oxo-1 H-inden-3-yl)-2H-indene-1,3-dione by DFT calculations, NMR and IR spectroscopy

Computational studies have been carried out at the DFT-B3LYP/6-31G(d) level of theory on the structural and spectroscopic properties of 2-(1-oxo-1 H-inden-3-yl)-2H-indene-1,3-dione (OID). Experimental studies were conducted on these parameters, including X-ray, FT-IR and 13C NMR spectroscopy. The optimized geometries of OID and its bonding characteristics as well as IR and NMR spectra have been calculated and analyzed. It was observed that the bond lengths and angles in the molecule, obtained by X-ray, IR and NMR at the level of theory, were in a good agreement with those of the experiment. The correlation between the theoretical and the experimental vibrational frequencies and the chemical shifts of the OID molecule were 0.994 and 0.991, respectively. The agreement mutually verified the accuracy of the experimental method and the validity of the applied mathematical model.     

On‐plate deposition of oxidized proteins to facilitate protein footprinting studies by radical probe mass spectrometry

The on‐plate deposition of oxidized proteins is described to advance footprinting applications by radical probe mass spectrometry (RP‐MS). An electrospray ionization (ESI) needle assembly mounted vertically over a 384‐target matrix‐assisted laser desorption/ionization (MALDI) plate enabled the limited oxidation of proteins as they were released in the charged droplets ahead of their deposition on the plate. This method combined with on‐plate proteolytic digestion protocols expedites the analysis of proteins oxidized by RP‐MS, and avoids the need to collect and reconstitute samples prior to analysis by MALDI mass spectrometry. Oxidation of peptides from solutions in water as well as an ammonium bicarbonate solution was investigated to test the optimal conditions required for on‐plate oxidation of proteins. These comprised of peptides with a wide range of reactive amino acids including Phe, Tyr, Pro, His, Leu, Met and Lys that were previously shown to oxidize in both electrospray discharge and synchrotron radiolysis based footprinting experiments. The on‐plate deposition of lysozyme oxidized at electrospray needle voltages of 6 and 9 kV were carried out to demonstrate conditions suitable for footprinting experiments as well as those that induce the onset of protein damage. Copyright © 2012 John Wiley & Sons, Ltd.     

Synthesis and biological evaluation of a novel 99mTc‐cyclopentadienyltricarbonyl technetium complex as a new potential brain perfusion imaging agent

A new cytectrene prototype of general formula RCpTc(CO)₃ (R = C₆H₅NHCO, Cp = cyclopentadienyl moiety) has been synthesized from N‐phenylferrocenecarboxamide 2 , characterized and evaluated as a potential brain perfusion imaging agent. An improved procedure has been developed to obtain both the ligand 2 , characterized by its solid‐state structure (orthorhombic, Pccn, a = 10.4443(2) Å, b = 26.1467(6) Å, c = 9.9977(3) Å), and the corresponding metallic Tc‐ and Re‐complexes in good yield. These latter complexes possessed similar HPLC retention times, thereby indicating identity of their molecular structures. The Tc‐complex ^99m Tc‐2 is lipophilic enough to cross the blood‐brain barrier. This complex exhibits good brain uptake (1.41% injected dose per gram tissue at 5 min) combined with a fairly good retention of radioactivity in brain (0.48% injected dose per gram tissue after 1 h). Then, the distribution of the activity at 5 min post‐injection in various rat brain regions showed a higher accumulation in the hippocampus area. The new ^99mTc‐cyclopentadienyltricarbonyl technetium complex reported here showed promising biological results, making it an interesting base for the development of a new generation of cytectrene as brain perfusion imaging agent. Copyright © 2011 John Wiley & Sons, Ltd.     

Synthesis and biological evaluation of 99mTc-ECF: a new ethionamide derivative for tuberculosis diagnosis

In this work we propose a technetium-99m-labeled derivative from Ethionamide (ETH), further referred to as ^99mTc-ECF for tuberculosis diagnosis. The biological features of this radioactive agent have been studied. The 2-ethylpyridine-4-carbothioamide-ferrocène (ECF) was chemically synthesized and then labeled with technetium-99m. It has been confirmed through this work that ^99mTc-ECF is obtained with high radiolabelling yield (>90 %). Radiochemical analysis of ^99mTc-ECF revealed that the molecule was efficiently labeled with a little free remaining pertechnetate. Only 1–2 % of the tracer was leached out from the complex at 24 h when incubated in serum at 37 °C which confirmed its high stability. The sensitivity test of ECF showed that the group of grafted ferrocenyl does not seem to have largely altered the active site of the molecule. In-vitro investigations were conducted using BCG (Bacille Calmette-Guérin) as analogue of Mycobacterium Tuberculosis and Listeria Monocytogenes as negative control. It was proved that for BCG, ECF has kept the bacteriostatic properties of the parent compound (ETH). In physiological conditions, the measured up-take of the tracer with live bacteria was about 24.1 and 7.1 % for BCG and Listeria Monocytogenese, respectively. The comparison of the ^99mTc-ECF accumulation at sites of BCG infected animals, which is expressed as target-to-non-target ratio (found to be equal to 2.15) with other radiotracers was discussed. This allowed us to consider that ^99mTc-ECF could be a reasonable radiotracer for mycobacterial infections. Obtained results were good and encourage to undergo a similar labeling for the Mycobacterium tuberculosis as perspective of this work.     

Effects of Some Parameters on Particle Size Distribution of Chitosan Nanoparticles Prepared by Ionic Gelation Method

In this research, chitosan nanoparticles were prepared based on the ionic gelation of chitosan with tripolyphosphate anions. Effects of parameters such as chitosan concentration, tripolyphosphate concentration, and reaction time on the particle size distribution were investigated. In order to determine optimum conditions, tests were designed by Qualitek-4 software, using Taguchi method. The best conditions were determined based on three factors at three levels. Therefore, the main object was to investigate the effect of some parameters on particle size distribution and determine the optimum conditions for preparing chitosan nanoparticles by ionic gelation, followed by evaluation of the physicochemical and structural properties. The size distribution of original chitosan and chitosan nanoparticles were determined by Laser Diffraction and Dynamic Light Scattering, respectively. The physicochemical properties of the chitosan nanoparticles were studied using SEM, TEM, XRD pattern, FTIR, UV–vis, TGA, and NMR spectra. The optimum chitosan concentration, tripolyphosphate concentration, and reaction time were found to be 1.0 mg/ml, 1.0 mg/ml, and 60 min, respectively.     

Cuminum cyminum fruits as source of luteolin- 7-O-glucoside,potent cytotoxic flavonoid against breast cancer cell lines

Abstract

Cuminum cyminum is famous for its spicy fruits used for culinary and therapeutic properties worldwide. Brine shrimp test was performed for detecting cytotoxic fractions and subfractions. Ethyl acetate (EA) and hexane (HE) fractions demonstrated LC₅₀ of 52.40 and 60.77 µg/ml against Artemia salina while other fractions showed no toxicity (LC₅₀> 500 µg/ml). Bioguided elucidation of EA and HE fractions were carried out and cytotoxicity of pure compounds were investigated against breast cancer cell lines (MCF-7 and MDA-MB-231) and normal cell line (NIH/3T3) by MTT assay. Four flavone structures as luteolin, apigenin, luteolin-7-O-glucoside and apigenin-7-O-glucoside from EA and cuminoid A from HE were purified and identified. Luteolin-7-O-glucoside demonstrated potent anticancer activities against MCF-7 cell line (IC₅₀ of 3.98 µg/ml) with selectivity index of 8.0. In conclusion, flavonoids especially luteolin-7-O-glucoside play a significant role in cytotoxic effect of C. cyminum fruits and can be introduced as candidate for chemopreventive and chemotherapeutic drugs.     

Novel 1,3-Thiazole Analogues with Potent Activity against Breast Cancer: A Design,Synthesis, In Vitro,and In Silico Study

Breast cancer is the most common cancer in women, responsible for over half a million deaths in 2020. Almost 75% of FDA-approved drugs are mainly nitrogen- and sulfur-containing heterocyclic compounds, implying the importance of such compounds in drug discovery. Among heterocycles, thiazole-based heterocyclic compounds have demonstrated a broad range of pharmacological activities. In the present study, a novel set of 1,3-thiazole derivatives was designed and synthesized based on the coupling of acetophenone derivatives, and phenacyl bromide was substituted as a key reaction step. The activity of synthesized compounds was screened against the proliferation of two breast cancer cell lines (MCF-7 and MDA-MB-231). Almost all compounds exhibited a considerable antiproliferative activity toward the breast cancer cells as compared to staurosporine, with no significant cytotoxicity toward the epithelial cells. Among the synthesized compounds, compound 4 exhibited the most potent antiproliferative activity, with an IC₅₀ of 5.73 and 12.15 µM toward MCF-7 and MDA-MB-231 cells, respectively, compared to staurosporine (IC₅₀ = 6.77 and 7.03 µM, respectively). Exploring the mechanistic insights responsible for the antiproliferative activity of compound 4 revealed that compound 4 possesses a significant inhibitory activity toward the vascular endothelial growth factor receptor-2 (VEGFR-2) with (IC₅₀ = 0.093 µM) compared to Sorafenib (IC₅₀ = 0.059 µM). Further, compound 4 showed the ability to induce programmed cell death by triggering apoptosis and necrosis in MCF-7 cells and to induce cell cycle arrest on MCF-7 cells at the G1 stage while decreasing the cellular population in the G2/M phase. Finally, detailed in silico molecular docking studies affirmed that this class of compounds possesses a considerable binding affinity toward VEGFR2 proteins. Overall, these results indicate that compound 4 could be a promising lead compound for developing potent anti-breast cancer compounds.     

Investigating the possibility of increasing cooling air flow in a hydrogenerator rotor fan

Journal of Thermal Analysis and Calorimetry - The possibility of increasing cooling airflow inside a hydrogenerator rotor fan is investigated. The rotor fan has a heat dissipation problem and it is...