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Synthesis and characterization of mixed ligands of antidiabetic zinc(II) complexes
Get PDFMSc (Chemistry), North-West University, Mafikeng Campus, 2016Diabetes Mellitus (DM), one of the most pandemic, universal and life-style related disease across the globe. It is described as a metabolic disorder of multiple aetiology, characterized by chronic hyperglycemia with disturbances of carbohydrate, fat and protein metabolisms which may result from defects in insulin secretion and insulin action. The disease may be classified as Type 1 and Type 2 DM according to the National Diabetes Data Group of the USA and the 2nd World Health Organization (WHO) Expert Committee on DM. The clinical method utilized to treat both types of the disease were reported to be defective: daily insulin injections several times a day are painful and elevate the levels of patient stress especially in young people and synthetic therapeutic agents often have some severe side effects. To this date, many research studies have been conducted to develop a new class of metallopharmaceutical compounds that may be able to minimize or eradicate the problematic situations reported on this clinical method.
Zinc(II) metal ion, which has many nutritional and pharmacological roles, along with its complexes has been identified to exhibit insulin mimetic activities. The mono ligand antidiabetic zinc(II) complexes consisting of amino acids such maltol and picolinic acid were reported to exhibit greater in vitro insulin mimetic activities and in vivo antidiabetic activities in diabetic rat animals. Mixed ligands zinc(II) complexes have been lagging behind. In this study, the complexes bis(maltolato)zinc(II), bis(picolinato)zinc(II) and the new complexes maltolato(picolinato)zinc(II), (N-methyl-N-phenyl, N-butyl-N-phenyl)dithiocarbamatozinc(II) and (2,2-bipyridine)[(N-methyl-N-phenyl, N-butyl-N-phenyl)dithiocarbamatozinc(II)] were synthesized and characterized using Infrared and Ultraviolet-visible spectroscopy, single crystal X-ray diffraction and microanalysis. In vitro evaluation tests were carried out by making use of C2C12 (skeletal muscle) cell lines. Cells were induced with Type 2 Diabetes Mellitus and treated with the synthesized zinc(II) coordination compounds. The results of the C2C12 cell line culture plates have shown the presence of insulin mimetic activities and are in line with the published work.Master
Synthesis, characterization, and anticancer activity of arene mono-ruthenium and heteroleptic mixed-valent diruthenium complexes
Get PDFTo contribute towards the good health and well-being sustainable development goal, this project aims to synthesize and characterize organometallic arene mono-ruthenium and diruthenium complexes that have anti-neoplastic properties against the oestrogen receptor positive MCF-7, and the triple negative aggressive and invasive MDA-MB-231 human breast cancer cell lines. The preparation of diruthenium complexes led to the formation of paddlewheel-type complexes having a general chemical formula [Ru2(O2CCH3)3(R-ap)Cl] (C1 - C8). On the other hand, the preparation of mono-ruthenium complexes led to the formation of the complexes [RuCl2(η6 - C6H5OCH2CH2OH)(R)] (C10 - C12), and the novel [RuCl(η6 - C6H5OCH2CH2OH)(P(OPh)3)(SnCl3)] (C13 and C14). All complexes were characterized using spectroscopic techniques such as IR, UV-visible, 1-D and 2-D NMR. The connectivity of atoms through space as well as the solid-state structures was confirmed using X-ray crystallography. The purity of all synthesized compounds was confirmed by high-resolution mass spectrometry (HR-MS), hyphenated chromatographic techniques (LC-MS) as well as melting points. Magnetic susceptibility studies were conducted to determine and confirm the number of unpaired electrons of the paramagnetic bimetallic complexes. Due to their mixed valent Ru2(II, III) metalcore, cyclic voltammetry measurements were recorded to study the redox behaviour of the investigated complexes. The cytotoxic experiments performed against human breast MCF-7 and MDA-MB-231 cancer cells suggest that all free anilinopyridinate (R-ap) ligands do not significantly inhibit the survival growth of both cell lines, whereas coordination of these ligands to a Ru2(II, III) metal-core to form [Ru2(O2CCH3)3(R-ap)Cl] complexes (where R = CH3 or F) improves the anticancer activity against the afore-mentioned human breast cancer cells. Anilinopyridinate-type ligands were synthesized through a facile nucleophilic aromatic substitution reaction between 2-bromopyridine and the corresponding substituted anilines. The generated R-ap ligands are such that the substituent R is varied with electron-withdrawing fluorine (F) and donating methyl (CH3) substituents (L1 - L8) at different positions of the aniline ring. Synthesis of the organometallic ruthenium arene complexes was achieved via cleavage of the known ruthenium dimer [RuCl2(η6 -C6H5OCH2CH2OH)]2 with phosphine ligands. This synthetic method yielded organometallic [RuCl2(η6 -C6H5OCH2CH2OH)(R)] complexes, where R = triphenyl phosphine (C10), triphenyl phosphite (C11), trimethyl phosphite (C12). Furthermore, the reactions of C10 and C11 with SnCl2 led to the formation of the novel complexes [RuCl(η6 -C6H5OCH2CH2OH)(PPh3)(SnCl3)] (C13) and [RuCl(η6 - C6H5OCH2CH2OH)(P(OPh)3)(SnCl3)], respectively. The desired diruthenium complexes were achieved via a metathesis displacement of an acetate ligand from the precursor tetraacetate complex [Ru2(O2CCH3)4Cl] by one substituted ap ligand. This afforded stable mixed-valent diruthenium(II, III) paddlewheel complexes with a general chemical formula [Ru2(O2CCH3)3(R-ap)Cl]. Complexes [Ru2(O2CCH3)3(4-CH3ap)Cl] (C3) and [Ru2(O2CCH3)3(4-Fap)Cl] (C8) show promising anticancer effects against MCF-7 cells, having an IC50 value of 39.0 µM and 49.1 µM, respectively with favourable selectivity towards the human breast MCF-7 cells. Clonogenic assay experiments showed that C3 inhibited the ability of MCF-7 cells to survive after 7 days of monitoring cell colony formation. Western blotting analysis suggests that C3 induces double-stranded DNA breaks, observed by the increase in protein expression levels of key DNA damage response marker, ɣ-H2AX. Furthermore, C3 activates the intrinsic apoptotic signalling molecular markers, particularly caspase-9 and its downstream substrate, PARP. The stability of C3 in DMSO and RPMI media solution (used in biological assays) was confirmed by UV-visible spectroscopy. The results obtained suggest that [Ru2(O2CCH3)3(R ap)Cl] complexes are stable in DMSO for over 7 days and react rapidly with the RPMI-1640 culture media. Preliminary mechanistic studies investigating the biological molecular targets of C3 were performed by following the interactions of C3 with salmon-sperm DNA, blue script plasmid DNA and glutathione (GSH). Experiments were probed using UV-visible spectroscopic and agarose gel electrophoresis techniques. Altogether, the results obtained and presented herein in this work substantiate that the potential use of ruthenium coordination compounds and organometallic complexes in cancer therapy continues to remain a vital approach in the discovery of potent metal-based anticancer therapeutic drug leads
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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