Journal articles on the topic 'Phenolic oxime ligands'

The use of the novel pro-ligand H₄L combining the complimentary phenolic oxime and diethanolamine moieties in one organic framework, results in the formation of the first example of a [Mn^III₁₂] truncated tetrahedron.

An unprecedented dinuclear CuII complex, [Cu2(L2)2], derived from a salamo-like chelating ligand H2L2, was produced by the cleavage of a newly synthesized, half-salamo-like ligand HL1 (2-[O-(1-ethyloxyamide)]oxime-3,5-dichloro-phenol). This was synthesized and characterized by elemental analyses, IR, UV–Vis and fluorescent spectra, single crystal X-ray diffraction analysis, and Hirshfeld surface analysis. X-ray crystallographic analysis indicated that the two CuII (Cu1 and Cu2) ions bore different (N2O3 and N2O2) coordination environments, the penta-coordinated Cu1 ion possessed a slightly twisted tetragonal pyramid geometry with the τ value τ = 0.004, and the tetra-coordinated Cu2 ion showed a slightly twisted square planar geometry. Interestingly, one oxime oxygen atom participated in the coordination reported previously. Moreover, an infinite two-dimensional layered supramolecular network was formed. Compared with HL1, the CuII complex possessed the characteristic of fluorescence quenching.

A new series of water soluble mixed ligand complexes [MII(L)(bpy)AcO].nH2O M = Cu, (n=1) (1); Co (2), Mn (3), Ni (4) (n=4) and Zn (5) (n=2) have been synthesized from 2-(2-Morpholinoethylimino)methyl)phenol Schiff base ligand (HL) and 2,2�-bipyridine in a 1:1:1 molar ratio. The resulting complexes were characterized by spectral techniques. The spectral data of these complexes suggest an octahedral geometry. In vitro antioxidant activity results of DPPH assay, hydroxyl radical, super oxide and nitric oxide for complexes (1-5) were compared with ligand (HL) and in vitro antimicrobial activities of all compounds were examined against selected bacterial and fungal strains which indicate that the complexes exhibit higher antimicrobial activity than free ligand (HL). Gel electrophoresis results indicated that, complexes (1) and (2) have exhibited more DNA cleavage efficiency than others. The intrinsic binding constant (Kb) values for the complexes (1-5) observed by electronic absorption technique were in the order of (1) ] (4) ] (5) ] (2) ] (3) and DNA binding affinity values for these complexes obtained by viscosity measurements were in the order of ethidium bromide ] (1) ] (2) ] (3) ] (4) ] (5).

Abstract Ground-contact stakes, made from defect-free southern yellow pine sapwood, were treated with water-borne copper(II) [ammoniacal copper carbonate, ACC, Cu(II)] alone, oil-borne oxine copper (Cu-8) alone, or a dual treatment of ACC followed by drying and then Cu-8. The treated stakes were installed at two locations in Mississippi (Dorman Lake and Saucier) in high- or severe-deterioration hazard zones and inspected after 69 months of exposure. Stakes treated with Cu(II) alone at the highest retention of 5.1 kg m−3 [copper retention is based on the copper oxide (CuO) weight, as is standard in the US] performed moderately well at the Saucier test site, with decay and termite ratings of 8.0 out of 10.0, but unsatisfactory at the Dorman Lake test plot, with decay and termite ratings both below 7.0. Samples treated with Cu-8 alone at the highest retention of 1.92 kg m−3 had poor termite protection, with ratings below 7 at both sites, and only fair decay ratings of 7.0 (Dorman Lake) and 7.6 (Saucier). In contrast, all stakes treated with Cu(II)/Cu-8 combinations, with at least 2.4 kg m−3 Cu(II) and 0.2 kg m−3 Cu-8, performed satisfactorily, with average decay and termite ratings all above 8.0 at both locations. The addition of Cu(II) to Cu-8 likely causes the di-ligand form [bis(8-hydroxyquinolinolate)Cu(II)] to equilibrate principally to the mono form. Thus, the combination of Cu(II) and Cu-8 appears to form a new compound with greater efficacy than either of the two starting “reagents” and, consequently, this mixture is not literally synergistic. Possible advantages of mono Cu-8 include: (1) the mono form may be easier to formulate in a water- or solvent-borne system than the commercial bis-Cu-8 biocide; (2) the preservative would have a relatively low metal content, which may make future disposal of treated wood easier; (3) this system would likely have much fewer metal corrosion problems than preservative systems formulated with uncomplexed copper(II); and (4) the two copper coordination sites that are not complexed with the ligand could bind to the carboxylic or phenolic groups in wood to make the mono form relatively leach-resistant.

To crucially comprehend the relaying factors behind the growth mechanism of ZnO nanostructures, the needs to understand the cause of preferences in the enhancement of desired physicochemical properties are essential. The particular oriented attachment (OA) is believed to become the cause of the classical growth pattern of ZnO nanostructures which is mainly controlled by the Ostwald ripening (OR) process. In the present work, the concerns over the systematic changes in size and the morphological surface of ZnO nanostructures upon exposure to tannic acid (TA) prepared by drop-wise method turns the particles to different surface adjustment state. Here, we assessed the TA capping ability and its tendency to influence the OA process of the ZnO nanostructures. The detailed process of the growth-based TA system via transmission electron microscopy (TEM), scanning electron microscopy (SEM), and FFT autocorrelation revealed the pH effect on their physical properties which proved the transition surface properties state of the particles from rough to smooth states due to oriented attachment. For pure ZnO nanostructures, the surface is almost smooth owing to the strong bonding particles which are then changed to coarsened surface structures upon the introduction of TA. Strong surface adsorption of Zn cations and phenol ligands mediated the agglomerated nanocrystals, surprisingly with smaller nanostructures dimension.

Polynuclear metal clusters frequently feature geometric structural features not common in traditional coordination chemistry. These structures are of particular interest to bioinorganic chemists studying metallocluster enzymes, which frequently possess remarkably unusual inorganic structures. The structure of the manganese cluster μ5-oxido-di-μ3-phenoxido-hexa-μ-phenoxido-hexakis(pyridine-κN)hexamanganese(II) pyridine monosolvate, [Mn5(C6H5O)8O(C5H5N)6]·C5H5N or MnII 5(μ-OPh)6(μ3-OPh)2(μ5-O)(Py)6·Py, containing an unusual trigonal bipyramidal central oxide, is described. The compound was isolated from a reaction mixture containing bis(trimethylsilylamido)manganese(II) and phenol. The central O atom is presumed to have originated as adventitious water. The molecule crystalizes in a primitive monoclinic crystal system and is presented in the centrosymetric P2/n space group. The molecule possesses crystallographically imposed twofold symmetry, with the central O atom centred on the twofold axis and surrounded by a distorted trigonal bipyramidal arrangement of Mn atoms, which are further bridged by phenoxide ligands, and terminally ligated by pyridine. A pyridine solvent molecule resides nearby, also situated on a crystallographic twofold axis. The cluster is compared to three closely related previously reported structures.

Unfortunately, COVID-19 is still a threat to humankind and has a dramatic impact on human health, social life, the world economy, and food security. With the limited number of suggested therapies under clinical trials, the discovery of novel therapeutic agents is essential. Here, a previously identified anti-SARS-CoV-2 compound named Compound 13 (1,2,5-Oxadiazole-3-carboximidic acid, 4,4′-(methylenediimino) bis,bis[[(2-hydroxyphenyl)methylene]hydrazide) was subjected to an iterated virtual screening against SARS-CoV-2 Mpro using a combination of Ligand Designer and PathFinder. PathFinder, a computational reaction enumeration tool, was used for the rapid generation of enumerated structures via default reaction library. Ligand designer was employed for the computerized lead optimization and selection of the best structural modification that resulted in a favorable ligand–protein complex. The obtained compounds that showed the best binding to Mpro were re-screened against TMPRSS2, leading to the identification of 20 shared compounds. The compounds were further visually inspected, which resulted in the identification of five shared compounds M1–5 with dual binding affinity. In vitro evaluation and enzyme inhibition assay indicated that M3, an analogue of Compound 13 afforded by replacing the phenolic moiety with pyridinyl, possesses an improved antiviral activity and safety. M3 displayed in vitro antiviral activity with IC50 0.016 µM and Mpro inhibition activity with IC50 0.013 µM, 7-fold more potent than the parent Compound 13 and potent than the antivirals drugs that are currently under clinical trials. Moreover, M3 showed potent activity against human TMPRSS2 and furin enzymes with IC50 0.05, and 0.08 µM, respectively. Molecular docking, WaterMap analysis, molecular dynamics simulation, and R-group analysis confirmed the superiority of the binding fit to M3 with the target enzymes. WaterMap analysis calculated the thermodynamic properties of the hydration site in the binding pocket that significantly affects the biological activity. Loading M3 on zinc oxide nanoparticles (ZnO NPs) increased the antiviral activity of the compound 1.5-fold, while maintaining a higher safety profile. In conclusion, lead optimized discovery following an iterated virtual screening in association with molecular docking and biological evaluation revealed a novel compound named M3 with promising dual activity against SARS-CoV-2. The compound deserves further investigation for potential clinical-based studies.

Transformation of methane, the most abundant and the least reactive compound of natural gas to valuable products is one of the most difficult chemical problems of great practical importance. In Nature, methane monooxygenase enzymes transform methane to methanol in water under physiological conditions. However, chemical analogs for such a transformation are unknown. Here, we show the mild and efficient aqueous oxidation of methane by hydrogen peroxide, an ecologically and biologically relevant oxidant catalyzed by supported μ-nitrido diiron phthalocyanine dimer, (FePc t Bu 4)2 N . This bio-inspired complex containing a stable Fe – N – Fe motif catalyzes the oxidation of methane to methanol which is further transformed to formaldehyde and formic acid as is demonstrated using 13 CH 4 and 18 O labelling. (FePc t Bu 4)2 N - H 2O2 system shows a high activity in the oxidation of benzene to phenol which occurs via formation of benzene oxide and exhibits NIH shift typically accociated with biological oxidation. Mechanistic features of oxidation of methane and benzene as well as detected intermediate hydroperoxo- and high valent oxo diiron complexes support an O-atom transfer reaction mechanism relevant to bio-oxidation.

Abstract Current drugs in the treatment of Multiple Myeloma (MM) result in cell death via a number of mechanisms including a direct effect on plasma cells as well as alteration in the BM microenvironment. Although effective to some extent, none of the drug mechanisms of action are fully targeting a biological process essential and necessary for PC survival. Among the FDA approved kinase inhibitors, few are based on natural scaffolds. 6-bromoindirubin-3'-oxime (6BIO) is a potent kinase inhibitor based on the natural 6-bromoindirubin scaffold. Indirubin and 6-bromoindirubin are two natural products that have found a particular interest in dye chemistry as the main constituent of indigo and Tyrian purple dyes. Recent findings discovered that 6BIO was a promising anti-cancer agent acting on the JAK/STAT signaling pathway mediating cell proliferation. After enhancement of the chemical structure of 6BIO, further reports exposed that MLS-2438 and MLS-2384 were Akt signaling pathway inhibitor (MLS-2438) and potent c-Src kinase direct inhibitors. A library containing 2000 natural molecules was constructed using several data platforms. Each molecule was processed through different filters such as tautomeric studies, protonation and steroisomerism status in order to be used for calculations of virtual evaluation. Two approaches were followed: the structure-based virtual screening and the ligand-based virtual screening. To achieve structural based virtual screening, binding and evaluation of the chemical relation of each molecule in the crystallographic structure of the proteasome β5 subunit was performed. In the ligand-based virtual screening, calculations were made to identify the structural similarities of each molecule with the known proteasome inhibitor, bortezomib. The results of both approaches were combined, the molecules ranked, and 100 out of 2000 were identified as strong potential bioactive hits for the β5 subunit. Out of these 100 molecules, the chemical structures of high interest were the following: indole alkaloids derivatives (indirubins), flavonoids, secoiridoids, simple phenolic acids and acetophenone. A rational selection of indirubins derivatives was conducted in order to study their cytotoxic effects on MM. Fifty indirubins derivatives were selected based on different criteria: structure, known/unknown targets, chemodiversity in substitution patterns. To explore the inhibitory effects of indirubins in MM, we performed the WST1 proliferation assay in three MM cell lines (H929, JJN3, L363). Initially, all the selected indirubins (~50 indirubins) were tested at 7.5μM in L363 cell line and proliferation results from the WST1 assay extracted after 24 hours of treatment. More than half of the indirubins tested displayed more than 50% reduction of the proliferation at 7.5μM. Interestingly, 10 out of the 50 indirubins tested reduced more than 80% proliferation after 24 hours. The most active indirubins were tested in H929 and JJN3 cell lines, where similar effects were seen after 24 hours of treatment. All tested indirubins acted in a dose-dependent manner. Based on our first set of data, we suggest that indirubins have significant anti-proliferative effects on MM cell lines. Among the most active indirubins, two molecules namely 805 and 673 emerged as attractive for further development. Compound 805 is an analog of MLS-2384 while compound 673 is an analog of MLS-2438. The latter derivative represents a promising candidate displaying an IC50below the micromolar range on H929 and JJN3 cells. To determine the kind of cell death caused by one of the most active indirubins, 673, cell cycle analysis was performed before and after treatment in H929 cell line. In particular changes in RNA expression of 84 genes key to cell cycle regulation were analyzed in H929 cell line. Our results show that among other genes, the ones which have a dramatic increase in their expression (>5 fold) are mainly involved in cell cycle arrest such as GADD45A, CDC34, TP53, CHEK1 and CHEK2. A more detailed analysis of the profiler array will be presented at the meeting. In conclusion, this is the first study to show the inhibitory effects of indirubins in MM. Further investigation of these compounds may offer a therapeutic advantage that would affect MM pathogenesis and treatment. Disclosures Kastritis: Amgen: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Genesis: Consultancy, Honoraria. Terpos:Amgen: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; BMS: Consultancy, Honoraria; Janssen: Consultancy, Honoraria. Dimopoulos:Amgen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Genesis: Consultancy, Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

A scary viral pneumonia (COVID-19) has recently engulfed the globe. The new strain of the virus, named SARS-CoV-2, belongs to the coronavirus family, so research aims to screen multimodal structure-based structure-design of ligands and drugs and then docked to the main viral protease to investigate the active binding sites. A new 3-acetyl-7-hydroxy coumarin (HL) and its Cu(II), Ni(II), Zn(II), and Mn(II) complexes have been formed and characterized by elemental analysis, IR, 1H NMR, and UV visible spectra, as well as magnetic and thermal measurements. Molar conductance experiments have shown that all complexes are non-ionic or non-electrolytes. IR spectra show that the ligand (HL) behaves as a bidentate monobasic ligand coordinating via the oxygen atom of the deprotonated phenolic -OH group and the nitrogen atom of the azo group (-N=N-), forming a six-member chelating ring. The molecular and electronic structures of the investigated compounds were also analyzed using quantum chemical calculations. The complexes’ thermal decomposition exposed the outer and inner water molecules as well as the end product, which is mainly metal oxide. The thermodynamic parameter ligand (HL) and its metal complexes are calculated using the Coats-Redfern and Horowitz Metzger methods. Using absorption spectra, the ligand (HL) binding behavior of the calf thymus DNA and its metal complexes were studied. A molecular docking simulation computational method is performed to screen the antiviral activity of drugs, natural drug activity, sources, and anti-SARS-CoV-2 genome inhibitory compounds. The primary virus protease collected from a Bank of Protein Data (PDB# 6YB7) and docked with a sequence of HL and its complexes. On the other hand, the prediction of binding between azo compound with the breast cancer receptor 3hb5-oxidoreductase and the prostate cancer mutant 2q7k – hormone was also made. The docking results were promised and indicated that the reported ligand can firmly bind to the SARS-CoV-2, breast, and prostate cancer leads to inhibition of its infectious impact. The cytotoxic activity of ligand (HL) and its metal complexes was tested against human cancer MCF-7 (breast cancer).

This report focuses on the application of zinc oxide nanoparticles (ZnO NPs) carrying phycomolecule ligands as a novel plant growth promoter aimed at increasing the crop productivity of purslane (<em>Portulaca oleracea</em> L.). Experiments were performed under controlled greenhouse conditions using a completely randomized design with nine replications. Purslane seeds were treated with four concentrations of ZnO NPs (0, 10, 100, and 500 mg L<sup>−1</sup>) and four concentrations of bulk ZnO (0, 10, 100, and 500 mg L<sup>−1</sup>). The ultrastructural characteristics of the leaves of the plants treated with of 500 mg L<sup>−1</sup> ZnO NPs were determined using transmission electron microscopy (TEM). The results indicated that the treatment with ZnO NPs increased the content of chlorophyll <em>a</em> and chlorophyll <em>b</em>, carotenoids, and total phenolic and flavonoid compounds significantly more than the treatment with bulk ZnO. Our findings also showed that the application of high concentrations of ZnO NPs is the most effective strategy to considerably induce the antioxidant capacity and enzymes of purslane plants. Furthermore, the seed germination percentage and sprout growth rates were significantly higher in the plants treated with 500 mg L<sup>−1</sup> of ZnO NPs (100% ±0.00), compared to the control plants (93.33% ±1.66). The TEM images revealed the concentration of ZnO NPs and cell membrane rupture, as well as a deformation in the shape of chloroplasts and a decrease in their number in the plants treated with 500 mg L<sup>−1</sup> ZnO NPs, compared to the control plants. Owing to their toxicity, high concentrations of ZnO NPs lead to oxidative stress in plants. Thus, our findings provide a new alternative strategy for increasing crop productivity, i.e., the application of ZnO NPs as a novel plant growth booster, in comparison with the bulk ZnO treatment.