Antioxidant activity and two new flavonoids from Washingtonia filifera

Two new flavonoids, 8-hydroxyisoscoparin (1) and luteolin 7-O-glucoside 4'-sulfate (2), along with eight known flavonoids, including luteolin 7-O-glucoside 2'-sulfate, were isolated and identified from Washingtonia filifera. All compounds were characterized by (1)H-NMR, (13)C-NMR, CI-MS, FABMS and UV. The antioxidant activities of various W. filifera extracts were determined.     

Effect of Bacterial Memory Dependent Growth by Using Fractional Derivatives Reaction-Diffusion Chemotactic Model

In this paper, numerical solutions of a reaction-diffusion chemotactic model of fractional orders for bacterial growth will be present. A new solution is constructed in power series. The fractional derivatives are described in the Caputo sense. We compare the experimental result obtained with those obtained by simulation of the chemotactic model without fractional derivatives. The results show that the solution continuously depends on the time-fractional derivative. The resulting solutions spread faster than the classical solutions and may exhibit asymmetry, depending on the fractional derivative used. We present results of numerical simulations to illustrate the method, and investigate properties of numerical solutions. The Adomian’s decomposition method (ADM) is used to find the approximate solution of fractional ‘reaction-diffusion chemotactic model. Numerical results show that the approach is easy to implement and accurate when applied to partial differential equations of fractional order.     

Pyrazoles and Isoxazoles Based Sulfanilamide and Phenazone as Antimicrobial Agents: Synthesis and Biological Activity

New pyrazole and pyridine derivatives have been synthesized from sulfanilamide and phenazone via diazotization and coupling with a wide range of α-CH acids followed by heterocyclization with hydrazine derivative, hydroxylamine and cyanoacetamide. The antimicrobial tests of the products demonstrate high to moderate activity against Gram (?ve) bacteria and the tested fungi. No positive action of the products is observed against Gram (+ve) bacteria.

     

Reaction of some coumarin and 4,6-diaryl-2H-pyran derivatives with secondary amines

The reaction of piperidine, morpholine, piperazine or dimethylamine with several coumarins, 3-bromocoumarin, 4,6-diaryl-2H-pyran-2-ones and 3-bromo-4,6-diaryl-2H-thiopyran-2-ones gave o-hydroxycinnamic acid amides, benzofurans, open-chain δ-oxoamides and thiophene derivatives, respectively.     

Syntheses, spectroscopic characterization and thermal behavior on novel binuclear transition metal complexes of hydrazones derived from 4,6-diacetylresorcinol and oxalyldihydrazine

4,6-Diacetylresorcinol (DAR) serves as precursor for the formation of different hydrazone ligands, which are di-, tetra- or hexa-basic with two symmetrical sets of O(2)N tridentate, O(2)N(2) tetradentate or O(4)N(2) hexadentate chelating sites. The condensation of 4,6-diacetylresorcinol (DAR) with oxalyldihydrazine (ODH), in the molar ratio 1:1 and 1:2, yields the corresponding hydrazone, H(6)L(a) and H(4)L(b), ligands, respectively. The structures of these ligands were elucidated by elemental analyses and IR, mass, (1)H NMR and UV-vis spectra. Reactions of the hydrazone ligands with cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), iron(III) and chromium(III) ions in 1:2 molar ratio afforded the corresponding transition metal complexes. A variety of binuclear transition metal complexes were obtained in its di-, tetra- or hexa-deprotonated forms. The structures of the newly prepared complexes were identified by elemental analyses and IR, UV-vis, mass, (1)H NMR and ESR spectra, as well as, magnetic susceptibility measurements and thermal gravimetric analysis (TGA). The bonding sites are the azomethine and CO oxygen atoms in either keto or enol forms and amino nitrogen atoms, and phenolic oxygen atoms. The metal complexes exhibit different geometrical structures such as tetrahedral and octahedral arrangements.     

C-Furyl glycosides, I: Synthesis and antimicrobial evaluation of C-furyl glycosides and chalcones derived therefrom

New C-furyl glycosides were synthesized in order to increase the number of compounds screened for antimicrobial activity. The antimicrobial activity showed that the bromo as well as the nitro derivatives were the most active compounds. Correspondence: Adel A.-H. Abdel-Rahman, Faculty of Science, Department of Chemistry, Menoufia University, Shebin El-Koam, Egypt.     

Effects of 3-amino-1,2,4-triazole on the inhibition of copper corrosion in acidic chloride solutions

Effects of 3-amino-1,2,4-triazole (ATA) on the inhibition of copper corrosion in 0.5 M HCl solutions have been studied using gravimetric, electrochemical, and Raman spectroscopy investigations. Weight-loss measurements after varied immersion periods revealed that the dissolution rate of copper decreased to a minimum, while the inhibition efficiency (zeta%) and consequently the degree of surface coverage (theta) increased with the presence of ATA and the increase of its concentration. Potentiodynamic polarization, chronoamperometric, and electrochemical impedance spectroscopy (EIS) measurements after 0, 24, and 48 h immersion of the copper electrode in the test solutions showed that the presence of ATA molecules significantly decreased cathodic, anodic, and corrosion (jcorr) currents and corrosion rates (Rcorr) and greatly increased polarization resistance (Rp), zeta%, and theta; this effect was increased on increasing the ATA content in the solution. Raman spectroscopy confirmed that ATA molecules strongly adsorbed onto the copper surface, blocking its active sites and preventing it from being corroded easily.     

EHD kelvin-helmholtz instability in viscous porous medium permeated with suspended particles

The electrohydrodynamic Kelvin-Helmholtz instability of the plane interface between two uniform, superposed viscous and streaming dielectric fluids permeated with suspended particles through porous medium is considered under the influence of a tangential electric field. In the absence of surface tension, it is found that perturbations transverse to the direction of streaming are unaffected by the presence of both streaming and the tangential electric field, if perturbations in the direction of streaming are ignored. For perturbations in all other directions there exists instability for a certain wavenumber range. In the presence of surface tension, it is found that the instability of this system is suppressed by the presence of the tangential electric field. Both the tangential electric field and the surface tension have stabilizing effects and they are able to suppress Kelvin-Helmholtz instability for small wavelength perturbations. The medium porosity reduces the stability range given in terms of a difference in streaming velocities and the electric field effect, while the suspended particles do not affect the above results.