Hamid Khaledi

Antibacterial Evaluation of Some Schiff Bases Derived from 2-Acetylpyridine and Their Metal Complexes

A series of Schiff bases derived from 2-acetylpyridne and their metal complexes were characterized by elemental analysis, NMR, FT-IR and UV-Vis spectral studies. The complexes were screened for anti-bacterial activity against Methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumanni (AC), Klebsiella pneumonie (KB) and Pseudomonas aeruginosa (PA) using the disc diffusion and micro broth dilution assays. Based on the overall results, the complexes showed the highest activities against MRSA while a weak antibacterial activity was observed against A. baumanii and P. aeruginosa.

Antioxidant, cytotoxic activities, and structure-activity relationship of gallic acid-based indole derivatives.

A new series of gallic hydrazones containing an indole moiety was synthesized through the reaction of gallic hydrazide and different indole carboxaldehydes. Their antioxidant activities were determined on DPPH radical scavenging and inhibition of lipid peroxidation. The in‐vitro cytotoxic activities of the compounds were evaluated against HCT‐116 (human colon cancer cell line) and MCF‐7 (estrogen‐dependent human breast cancer cell line) by the MTT method. An attempt to correlate the biological results with their structural characteristics has been done. A limited positive structure activity relationship was found between cytotoxic and antioxidant activities.

Synthesis, Characterization, X-ray crystallography, acetyl cholinesterase inhibition and antioxidant activities of some novel ketone derivatives of gallic hydrazide-derived schiff bases

Alzheimer’s disease (AD) is the most common form of dementia among older people and the pathogenesis of this disease is associated with oxidative stress. Acetylcholinesterase inhibitors with antioxidant activities are considered potential treatments for AD. Some novel ketone derivatives of gallic hydrazide-derived Schiff bases were synthesized and examined for their antioxidant activities and in vitro and in silico acetyl cholinesterase inhibition. The compounds were characterized using spectroscopy and X-ray crystallography. The ferric reducing antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays revealed that all the compounds have strong antioxidant activities. N-(1-(5-bromo-2-hydroxyphenyl)-ethylidene)-3,4,5-trihydroxybenzohydrazide (2) was the most potent inhibitor of human acetyl cholinesterase, giving an inhibition rate of 77% at 100 μM. Molecular docking simulation of the ligand-enzyme complex suggested that the ligand may be positioned in the enzyme’s active-site gorge, interacting with residues in the peripheral anionic subsite (PAS) and acyl binding pocket (ABP). The current work warrants further preclinical studies to assess the potential for these novel compounds for the treatment of AD.

Butylated hydroxytoluene analogs: synthesis and evaluation of their multipotent antioxidant activities.

A computer-aided predictions of antioxidant activities were performed with the Prediction Activity Spectra of Substances (PASS) program. Antioxidant activity of compounds 1, 3, 4 and 5 were studied using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and lipid peroxidation assays to verify the predictions obtained by the PASS program. Compounds 3 and 5 showed more inhibition of DPPH stable free radical at 10−4 M than the well-known standard antioxidant, butylated hydroxytoluene (BHT). Compound 5 exhibited promising in vitro inhibition of Fe2+-induced lipid peroxidation of the essential egg yolk as a lipid-rich medium (83.99%, IC50 16.07 ± 3.51 µM/mL) compared to α-tocopherol (α-TOH, 84.6%, IC50 5.6 ± 1.09 µM/mL). The parameters for drug-likeness of these BHT analogues were also evaluated according to the Lipinski’s “rule-of-five” (RO5). All the BHT analogues were found to violate one of the Lipinski’s parameters (LogP > 5), even though they have been found to be soluble in protic solvents. The predictive polar surface area (PSA) and absorption percent (% ABS) data allow us to conclude that they could have a good capacity for penetrating cell membranes. Therefore, one can propose these new multipotent antioxidants (MPAOs) as potential antioxidants for tackling oxidative stress and lipid peroxidation processes.

3,4,5-Trihydr-oxy-N'-(1H-indol-3-yl-methyl-idene)benzohydrazide penta-hydrate.

The two aromatic parts of the title compound, C16H13N3O4·5H2O, are connected through a conjugated –CH=N–NH–C(O)– fragment, giving an almost planar molecule. The organic molecules and uncoordinated water molecules are linked by N—H⋯O and O—H⋯O hydrogen bonds into a three-dimensional network.

Nitrite ion sensing properties of ZnTiO3–TiO2 composite thin films deposited from a zinc–titanium molecular complex

A titanium based heterobimetallic molecular precursor, [Zn2Ti4(μ-O)6(TFA)8(THF)6]·THF (1) (where TFA = trifluoroacetato; THF = tetrahydrofuran), has been designed and scrutinised for its various physicochemical properties by melting point analysis, microanalysis, Fourier transform infra-red spectroscopy, proton nuclear magnetic resonance spectroscopy, thermogravimetry and single crystal X-ray structural analysis. ZnTiO3–TiO2 composite thin films were grown on a fluorine doped tin oxide (FTO) coated conducting glass substrate at 550 °C from three different solutions of (1) viz. methanol, THF and acetonitrile, by the aerosol-assisted chemical vapour deposition technique. The phase identification, chemical composition and microstructure of the fabricated thin films that were probed by powder X-ray diffraction, Raman spectroscopy, energy dispersive X-ray analysis and scanning electron microscopy revealed the formation of a 1 : 1 ratio of ZnTiO3 : TiO2 composite microspheres of diverse designs and textures depending on the type of deposition solvent used. The direct band gap energy of 3.1 eV was estimated by UV-visible spectrophotometry of the ZnTiO3–TiO2 film fabricated from methanol solution and the film electrode was further tested as an electrochemical sensor for the detection of nitrite ions.

Indolenine meso-Substituted Dibenzotetraaza[14]annulene and Its Coordination Chemistry toward the Transition Metal Ions MnIII, FeIII, CoII, NiII, CuII, and PdII

A new dibenzotetraaza[14]annulene bearing two 3,3-dimethylindolenine fragments at the meso positions (LH(2)), has been synthesized through a nontemplate method. X-ray crystallography shows that the whole molecule is planar. The basicity of the indolenine ring permits the macrocycle to be protonated external to the core and form LH(4)(2+)·2Cl(-). Yet another structural modification having strong C-H···π interactions was found in the chloroform solvate of LH(2). The latter two modifications are accompanied by a degree of nonplanar distortion. The antiaromatic core of the macrocycle can accommodate a number of metal ions, Mn(III), Fe(III), Co(II), Ni(II) and Cu(II), to form complexes of [Mn(L)Br], [Mn(L)Cl], [Fe(LH(2))Cl(2)](+)·Cl(-), [Co(L)], [Ni(L)], and [Cu(L)]. In addition, the reaction of LH(2) with the larger Pd(II) ion leads to the formation of [Pd(2)(LH(2))(2)(OAc)(4)] wherein the macrocycle acts as a semiflexible ditopic ligand to coordinate pairs of metal ions via its indolenine N atoms into dinuclear metallocycles. The compounds LH(2), [Co(L)], and [Ni(L)] are isostructural and feature close π-stacking as well as linear chain arrangements in the case of the metal complexes. Variable temperature magnetic susceptibility measurements showed thermally induced paramagnetism in [Ni(L)].

A new chromanone acid from the stem bark of Calophyllum teysmannii

A new chromanone acid, namely caloteysmannic acid (1), along with three known compounds, calolongic acid (2), isocalolongic acid (3) and stigmasterol (4) were isolated from the stem bark of Calophyllum teysmannii. All these compounds were evaluated for their cytotoxic and antioxidant activities in the MTT and DPPH assays, respectively. The structure of compound 1 was determined by means of spectroscopic methods including 1D and 2D NMR experiments as well as HR-EIMS spectrometry. The stereochemical assignment of compound 1 was done based on the NMR results and X-ray crystallographic analysis. The preliminary assay results revealed that all the test compounds displayed potent inhibitory activity against HeLa cancer cell line, in particular with compound 1 which exhibited the highest cytotoxic activity comparable to the positive control used, cisplatin. However, no significant antioxidant activity was observed for all the test compounds in the DPPH radical scavenging capacity assay.

Structural systematics of RSn(S 2CN R′ R″) 2Cl compounds

Abstract Three new organotin(IV) structures of general formula RSn(S 2CN R′ R″) 2Cl, where R′ ≠ R″, namely MeSn · [S 2CN(Me)(Cy)] 2Cl ( 1), MeSn[S 2CN( i-Pr)(CH 2Ph)] 2Cl ( 2) and PhSn[S 2CN(Et)( i-Pr)] 2Cl ( 3) are described. Each structure features tin in a distorted octahedral geometry defined by a C ClS 4donor set as a result of two chelating dithiocarbamate ligands. In all cases the tin-bound carbon and chloride atoms are cis. The shorter Sn–S bond lengths in 3are correlated with the presence of the relatively more electronegative Sn-bound phenyl substituent. The new structures conform to the structural motif adopted by all other compounds with the formula RSn(S 2CN R′ R″) 2Cl, where R′ = R″, suggesting the unsymmetrical substitution pattern of the dithiocarbamate ligands in the present study does not influence the adoption of this structural motif. The homogeneity in the structural motif notwithstanding, non-systematic variations in geometric parameters are found in these structures indicating an overall influence of crystal packing upon molecular geometry.

N′-[1-(5-Bromo-2-hydroxy­phen­yl)ethyl­idene]-3,4,5-trihydroxy­benzohydrazide dimethyl sulfoxide solvate trihydrate

The benzohydrazide molecule in the title compound, C15H13BrN2O5·C2H6OS·3H2O, is almost planar with an r.m.s. deviation for the non-H atoms of 0.078 Å. The organic molecules, water and dimethyl sulfoxide solvent molecules are linked by N—H⋯O, O—H⋯O and O—H⋯S intermolecular hydrogen bonds, forming zigzag chains along the a axis. Intramolecular O—H⋯O and O—H⋯N hydrogen bonds also occur.