Voltammetric analysis using a self-renewable non-mercury electrode

Galinstan is a new kind of electrode material and the galinstan electrode is a promising alternative to the commonly used mercury electrodes. The eutectic mixture of gallium, indium and tin is liquid at room temperature (m.p. −19°C) and its voltammetric behaviour is similar to that of mercury. The potential windows of use were determined for different pH values and are similar to those obtained with conventional mercury electrodes. Furthermore, the high hydrogen overpotential, which is characteristic for mercury, can be observed when galinstan is used as electrode material. Galinstan can be employed as a liquid electrode in the voltammetric analysis of different metal ions, such as lead and cadmium, in different supporting electrolytes. Our results indicate that the non-toxic liquid alloy galinstan could therefore become immensely important in electrochemical research as a potential surrogate material for mercury.     

New palladium(II)-catalyzed asymmetric 1,2-dibromo synthesis

[reaction: see text] The oxidation of olefins by chiral monometallic and bimetallic Pd(II)-Cu(II) catalysts in bromide-containing aqueous-THF reaction mixtures produced chiral 1,2-dibromides. With alpha-olefins, the ee's were about 95% while most of the internal alkenes gave somewhat lower enantioselectivities ( approximately 80%).     

Synthesis,EGFR-TK inhibition and anticancer activity of new quinoxaline derivatives

Abstract

Ethyl 4-substituted-3-oxo-quinoxaline-2-carboxylates 3–5 were obtained via alkylation of ethyl 3-oxo-3,4-dihydroquinoxaline-2-carboxylate (1). Compound 1 was heterocyclized using hydrazines, ethylenediamine, and ethanolamine to give pyrazoloquinoxalines 6, 7, diazepinoquinoxaline 8, and oxazepinoquinoxaline 10. The quinoxaline-2-carboxamides 9, 11, 12 were prepared via condensation of compound 1 with different amines. Compound 1 was thiated using Lawesson’s reagent affording quinoxaline-3-thione 13, in fair yield. In addition, the reaction of 4-methyl-3-oxoquinoxaline 3 with some binucleophiles led to a series of new oxoquinoxaline derivatives 14–18. The molecular structure of compounds 1, 3, and 9 was confirmed by X-ray crystallography.

The anti-proliferative activity showed that among all the tested compounds, compounds 3, (IC₅₀ 2.51?±?3.0, 4.22?±?1.6 and 2.27?±?1.9?µM), 11 (IC₅₀ 1.32?±?2.61, 1.41?±?1.23 and 1.18?±?1.91?µM) and 17 (IC₅₀ 1.72?±?1.32, 1.85?±?0.94 and 1.92?±?4.83?µM) showed noteworthy anti-proliferative effects against the three cancer cell lines, HCT116, HePG2 and MCF7, respectively, compared to the reference drugs doxorubicin (IC₅₀ 1.41?±?0.58, 0.90?±?0.62 and 1.01?±?3.02?µM) and erlotinib (IC₅₀ 1.63?±?0.81, 1.57?±?0.62 and 1.49?±?0.54?µM). Compounds 3 (0.899?nM), 11 (0.508?nM) and 17 (0.807) showed strong EGFR inhibitory activity compared to Erlotinib (0.439?nM) and these results are in agreement with the docking study. These results suggest that compounds could probably be promising anticancer agents with EGFR inhibitory activity.     

Phytoconstituents and pharmacological activities of cyanobacterium Fischerella ambigua

Cyanobacteria, also known as blue-green algae, are known to be a rich source of secondary metabolites with diverse chemical structures and biological activities. Over 1100 natural constituents of cyanobacterial origin have been reported in the literature. These include various natural biologically active constituents with antimicrobial, antiviral, immunosuppressive, and anticancer activities. Terrestrial cyanobacteria of genus Fischerella (Family Fischerellaceae), belonging to order Stigonematales have recently received enormous attention from the researchers due to the presence of vast array bioactive compounds. Fischerella species are filamentous cyanobacteria with creeping thallus and sheath in filaments. Several species within the genus are known to produce interesting bioactive constituents. Perhaps the best characterized are F. ambigua and F. muscicola, which have been reported to produce antibacterial, antifungal and antialgal isonitrile containing indole alkaloids, such as hapalindoles, ambiguine isonitriles, fischerindoles, and wetwitindolinones. Keeping in mind these resources, a detailed literature survey on a cultured, fresh water and terrestrial cyanobacterium Fischerella ambigua (N?g.) Gom. has been carried out. The current review describes the chemical constituents isolated from different extracts of Fischerella ambigua, as well as their biological activities.     

Design and development of novel single multiplex system incorporating 26 rapidly mutating Y-STRs; 26 RM Yplex

This article details the development of a single multiplex system amplifying 26 rapidly mutating Y-STR markers. A sequenced allelic ladder, constructed for calling alleles of all loci, is introduced. The multiplex system shows the ability to address the limitations of Y-STRs commercial kits in differentiating closely related males. The multiplex performed well in the prevalidation tests and showed great potential to be used in forensic casework.     

The effect of steric hindrance on the Fe(II) complexes of triazine-containing ligands

Fe(II) complexes based on ligands containing a 1,3,5-triazine core have been synthesised and characterised and their electrochemical, spectroscopic and magnetic properties have also been investigated. The incorporation of various substituted metal-binding heterocycles into the 2,4-positions of the triazine allows the properties of the complexes to be modified considerably. Whereas the magnetic moments of the pyridyl (1b: 2.4 B.M.) and pyrazyl (1c: 4.2 B.M.) substituents lead to spin transitions, the 6-picolyl (1d: 5.4 B.M.) substituent is a pure Curie paramagnet at 300 K. Interestingly, the Fe(II) complex of bromo-phenyl-2,2′:6″,2?-terpyridine (1a) displays significant anion effects in the solid state, with the ClO₄ salt exhibiting major diamagnetic contributions (2.1 B.M. at 300 K) and the PF₆ salt has more significant paramagnetic contributions (3.5 B.M. at 300 K). The Fe–N bond distances observed in the 6-picolyl complex [Fe(1d)₂](ClO₄)₂ for both the central rings 2.084 (5) Å and the distal rings 2.254 (4) and 2.369 (4) Å are significantly longer than those of the pyridyl complex [Fe(1b)₂](ClO₄)₂ (centre: 1.869 (4) Å; distal: 1.992 (4) Å; distal: 2.005 (4) Å) due to steric strain, thus generating high-spin [Fe(1d)₂](ClO₄)₂.     

Two fac‐tricarbonylrhenium(I) azadipyrromethene (ADPM) complexes: ligand‐substitution effect on crystal structure

The crystal structures of fac‐(acetonitrile‐κN)(2‐{[3,5‐bis(4‐methoxyphenyl)‐2H‐pyrrol‐2‐ylidene‐κN¹]amino}‐3,5‐bis(4‐<!?tlsb=0.2pt>methoxyphenyl)‐1H‐pyrrol‐1‐ido‐κN¹)tricarbonylrhenium(I)–hexane–acetonitrile (2/1/2), [Re(C₃₆H₃₀N₃O₄)(CH₃CN)(CO)₃]·0.5C₆H₁₄·CH₃CN, (2), and fac‐(2‐{[3,5‐bis(4‐methoxyphenyl)‐2H‐pyrrol‐2‐ylidene‐κN¹]amino}‐3,5‐bis(4‐methoxyphenyl)‐1H‐pyrrol‐1‐ido‐κN¹)tricarbonyl(dimethyl sulfoxide‐κO)rhenium(I), [Re(C₃₆H₃₀N₃O₄)(C₂H₆OS)(CO)₃], (3), at 150 K are reported. Both complexes display a distorted octahedral geometry, with a fac‐Re(CO)₃ arrangement and one azadipyrromethene (ADPM) chelating ligand in the equatorial position. One solvent molecule completes the coordination sphere of the Re^I centre in the remaining axial position. The ADPM ligand shows high flexibility upon coordination, while retaining its π‐delocalized nature. Bond length and angle analyses indicate that the differences in the geometry around the Re^I centre in (2) and (3), and those found in three reported fac‐Re(CO)₃–ADPM complexes, are dictated mainly by steric factors and crystal packing. Both structures display intramolecular C—H...N hydrogen bonding. Intermolecular interactions of the Csp²—H...π and Csp²—H...O(carbonyl) types link the discrete monomers into extended chains.     

Design and Synthesis of New Thiophene/Thieno[2,3-d]pyrimidines along with Their Cytotoxic Biological Evaluation as Tyrosine Kinase Inhibitors in Addition to Their Apoptotic and Autophagic Induction

This work describes the synthesis and anticancer activity against kinase enzymes of newly designed thiophene and thieno[2,3-d]pyrimidine derivatives, along with their potential to activate autophagic and apoptotic cell death in cancer cells. The designed compounds were scanned for their affinity for kinases. The results were promising with affinity ranges from 46.7% to 13.3%. Molecular docking studies were performed, and the compounds were then screened for their antiproliferative effects. Interestingly, compounds 8 and 5 resulted in higher cytotoxic effects than the reference standard against MCF-7 and HepG-2. The compounds were evaluated for their induction of apoptosis and/or necrosis on HT-29 and HepG-2. Three compounds induced significant early apoptosis compared to untreated control HT-29 cells, and four derivatives were more significant compared to untreated HepG-2 cells. We further investigated the effect of four compounds on the autophagy process within HT-29, HepG-2, and MCF-7 cells with flow cytometry. Similar to the apoptosis results, compound 5 showed the highest autophagic induction among all compounds. The potential inhibitory activity of the synthesized compounds on kinases was assessed. Screened compounds showed inhibition activity ranging from 41.4% to 83.5%. Compounds recorded significant inhibition were further investigated for their specific FLT3 kinase inhibitory activity. Noticeably, Compound 5 exhibited the highest inhibitory activity against FLT3.