Flavonoids of Alcea rosea L. and their immune stimulant,antioxidant and cytotoxic activities on hepatocellular carcinoma HepG-2 cell line

Alcea rosea L. is widely cultivated in gardens of Egypt as an ornamental plant and it has a great history of folkloric medicinal uses. In the present work, phytochemical investigation of the alcoholic extract of the flowers of A. rosea L. led to the isolation of six flavonoids (1–6). Dihydrokaempferol-4′-O-β-d-glucopyranoside (1), dihydrokaempferol (2), kaempferol-3-O-[6″-(E-coumaroyl)]-β-d-glucopyranoside (3), kaempferol-3-O-β-d-glucopyranoside (4), Apigenin (5) and kaempferol-3-O-α-l-rhamnopyranosyl-(1′″→6″)-β-d-glucopyranoside (6). Four of the isolated compounds were evaluated for their antioxidant, immunostimulant and cytotoxic activities against HepG-2 cell line. Compound (3) showed potent cytotoxic activity against HepG-2 cell line with high selectivity towards hepatocellular carcinoma in vitro (with IC₅₀ = 3.8 μg/mL). Compounds 1 and 2 exhibited significant antioxidant activity and compound 4 showed a significant immune stimulant activity. Compound 1 is isolated for the first time from genus Alcea and this is the first report for its biological investigation.     

Molecular-level approach to inhibit degradations of alkanethiol self-assembled monolayers in aqueous media

A molecular-level approach is developed to prevent or inhibit the degradation processes of alkanethiol self-assembled monolayers (SAMs). Previous studies revealed two degradation pathways: direct desorption and oxidation-desorption. By use of scanning tunneling microscopy (STM) and atomic force microscopy (AFM), in situ and time-dependent imaging reveals and confirms that degradations of alkanethiol SAMs on gold mainly initiate at defect sites, such as domain boundaries and vacancy islands, and then propagate into the ordered domains. Our approach targets at attaching small molecules with preferred adhesion to the defects. The best candidates are aqueous media containing a small amount of amphiphilic surfactant molecules, such as N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO). High-resolution studies demonstrate that DMSO and DMF molecules attach to SAM surfaces and more favorably at defect sites, forming relatively stable adsorbates. This attachment increases the activation energy sufficiently to inhibit both degradation pathways. The robustness of this approach has been investigated as a function of surfactant concentration, solution temperature, and the stirring condition. Molecular-level mechanisms and energetics for degradation inhibition of SAMs are also discussed in detail.     

Electronic spectra and electrochemistry of disubstituted 2,2′-bipyridinetetracarbonylmolybdenum complexes. Solvent and substituent effects

Electronic absorption spectra of cis-[Mo(CO)₄(n,n′-X₂-bipy)] (n = 4, X = NMe₂, NH₂, OMe, CMe₃, Me, H, Ph, CH:CHPh, CO₂H, Cl, CO₂Me, NO; n=5, X = Me, CO₂H) have been measured at ambient temperature in a variety of solvents of different polarity. Emission spectra from glasses containing the complexes at 77 K have also been measured. The influence of the substituent X on the spectroscopic properties is correlated with the Hammett parameters, σ_p (X) and σ_p⁺ (X). The effect of solvent is correlated with the Taft-Kamlet parameter, π^★, indicating charge redistribution along the permanent dipole axis of the complex. The oxidation and reduction potentials in solution are simply related to the electronic effect of the substituent group, X, and are relatively independent of the solvent. The influence of the metal on these properties is not significant.     

Adsorption and controlled release of Chlortetracycline HCl by using multifunctional polymeric hydrogels

Adsorption and controlled release of Chlortetracycline HCl to and from multifunctional polymeric materials (HEMA/MAA) hydrogels were investigated. P(HEMA/MAA) hydrogels were synthesized by gamma radiation-induced copolymerization of 2-hydroxyethylmethacrylate (HEMA) and methacrylic acid (MAA) in aqueous solution. The influence of copolymer composition and pH value of the surrounding medium on the type of water diffusion into the glassy polymer were discussed. Drug, Chlortetracycline HCl containing hydrogels, with different drug concentration to polymer ratios, was loaded by direct adsorption method. The influence of MAA content in the gel on the adsorption capacities of hydrogel was studied. Chlortetracycline HCl adsorption capacity of hydrogels was found to increase from 8 to 138 mg Chlortetracycline HCl per gram dry gel with increasing amount of MAA in the gel system and drug concentration. The effect of pH on the releasing behavior of Chlortetracycline HCl from gel matrix was investigated. In vitro drug release studies in different buffer solutions show that the basic parameters affecting the drug release behavior of hydrogel are the pH of the solution and MAA content of hydrogel.     

Synthesis and Chemistry of 4-Aroyl-3-oxo- and 3-Chloropyridazine Derivatives

4H,5H-6-Phenyl (1a) and 6-p-phenoxyphenyl (1b) pyridazin-3(2H)-ones were reacted with aromatic aldehydes to give 4-arylmethylpyridazm-3(2H)-ones (2a-g), Oxidation of (2a-g) with various oxidising agents (selenium dioxide in ethanol or chromium trioxide in acetic acid) gave 4-aroyl-6-arylpyridazin-3(2H)-ones (3a-g). Chlorination of (3a-g) with phosphorous oxychloride afforded 4-aroyl-6-aryl-3-chloropyridazine (4a-g). 1H-3-Aryl-5-phenylpyrazolo[3,4-c]pyridazines (5a-d) were obtained by heating (4a-d) with excess hydrazine hydrate. Hydroxyamination of (3e-g) with iydroxylamine gave aryl-4(6-p-phenoxyphenyl-2,3-dihydro-3-oxo)pyridazinyl oxime (6a-c). Silylation of oximes (6b & 6c) gave (7a & 7b) as acyclic compound instead of the expected seven - membered - ring compound (8).     

Synthesis, 13C-NMR characterization and antimicrobial properties of a novel series of 3-(N-Substituted thiocarbamoyl)hydrazino-1,2,4-triazino-[5,6-b]indole derivatives

A series of 3-(N-substituted thiocarbamoyl)hydrazino-1,2,4-triazino[5,6-b]indole derivatives 3–22 has been synthesized and evaluated for in vitro antimicrobial activity. Although some of the products displayed significant activity against Staphylococcus aureus, Escherichia coli and Candida albicans, their bactericidal and bacterostatic potencies were lower than that of penicillin G. The structure of the products was assigned upon the basis of their infrared, ¹H-nmr and ¹³C-nmr spectra.     

Electronic and Conformational Effects on the Lipophilicity of Isomers and Analogs of the Neurotoxin 1-Methyl-4-phenylpyridinium (MPP+)

A number of isomers and analogs of the neurotoxin 1-methyl-4-phenylpyridinium (MPP⁺) were examined for their lipophilic behavior. Their partition coefficients in the 1-octanol/H₂O system were measured by centrifugal partition chromatography (CPC), which, being much faster and markedly more precise than the classical shake-flask method, proved a very promising alternative for assessing lipophilicity. A smaller-than-expected lipophilicity was shown by the ortho-isomer of MPP⁺ (M2PP⁺) and is explained in terms of electronic effects and rigidity, as revealed by UV and NMR spectroscopy, and conformational analysis. Implications of lipophilicity in modulating the in vivo dopaminergic neurotoxicity of the examined compounds are also discussed.     

Symmetrical and unsymmetrical incorporation of active biological monomers on the surface of phosphorus dendrimers

Phosphorus-containing dendrimers are attractive carriers for the delivery of bioactive molecules due to their very particular architecture, globular shape and chemical and physical properties. Herein we report a simple synthetic approach of ethacrynic acid derivatives loaded-phosphorus dendrimers by symmetrical grafting of ethacrynic acid analogues by nucleophilic substitution of each chlorine of P(S)Cl₂ end groups. We report also for the first time an unsymmetrical grafting of two different phenol derivatives by a selective substitution of one chlorine of P(S)Cl₂ end group followed by the grafting of the second phenol.     

Determination of three antidepressants in urine using simultaneous derivatization and temperature‐assisted dispersive liquid–liquid microextraction followed by gas chromatography–flame ionization detection

This paper presents a fast and simple method for the extraction, preconcentration and determination of fluvoxamine, nortriptyline and maprotiline in urine using simultaneous derivatization and temperature‐assisted dispersive liquid–liquid microextraction (TA‐DLLME) followed by gas chromatography–flame ionization detection (GC‐FID). An appropriate mixture of dimethylformamide (disperser solvent), 1,1,2,2‐tetrachloroethane (extraction solvent) and acetic anhydride (derivatization agent) was rapidly injected into the heated sample. Then the solution was cooled to room temperature and cloudy solution formed was centrifuged. Finally a portion of the sedimented phase was injected into the GC‐FID. The effect of several factors affecting the performance of the method, including the selection of suitable extraction and disperser solvents and their volumes, volume of derivatization agent, temperature, salt addition, pH and centrifugation time and speed were investigated and optimized. Figures of merit of the proposed method, such as linearity (r² > 0.993), enrichment factors (820–1070), limits of detection (2–4 ng mL^?1) and quantification (8–12 ng mL^?1), and relative standard deviations (3–6%) for both intraday and interday precisions (concentration = 50 ng mL^?1) were satisfactory for determination of the selected antidepressants. Finally the method was successfully applied to determine the target pharmaceuticals in urine. Copyright © 2014 John Wiley & Sons, Ltd.     

Molecular dynamics and alignment studies of silica-filled 4-pentyl-4′-cyanobiphenyl (5CB) liquid crystal

A comprehensive study of the dielectric properties of 4-pentyl-4′-cyanobiphenyl (5CB) liquid crystal filled with silica particles (particle size 30–80 nm, concentration 2, 3, 5, 10 and 15 wt%). Dielectric spectroscopy in the frequency range 100 to 10 7 Hz was applied to investigate the influence of the filler on the dynamic behaviour of the liquid crystal molecules in both the nematic and isotropic phases. In this frequency range one relaxation process is observed (at f>10⁶ Hz). The dynamical behaviour of the 5CB liquid crystal is described by the Cole-Cole relaxation function. The temperature dependence of the relaxation time obeys the empirical Arrhenius equation. The activation energies are approximately 75 kJ mol¹ for the pure 5CB sample in the nematic phase and 50 kJ mol¹ for the 5 wt% silica-filled 5CB sample. These values are compared with the corresponding literature values. The reversible electro-mechanical response of these samples under the influence of an applied a.c. electric field is investigated.